Uploaded byIMPERIALXGAMING
PDF, PPTX20 views

Chapter 01 Java Programming Basic Java IDE JAVA INTELLIEJ

This document provides an introduction to computers, programs, Java, and the basic components of a computer system. It discusses the objectives of understanding computer basics like the CPU, memory, storage devices, input/output, and how programs are run. It then provides details on programming languages like machine language, assembly language, and high-level languages like Java. It explains how source code is translated to machine code through interpreting or compiling. Finally, it discusses why Java is well-suited for developing applications on the Internet.

Download as PDF, PPTX
Chapter 1 Introduction to Computers, Programs, and Java 1
Objectives • To understand computer basics, programs, and operating systems (§§1.2–1.4). • To describe the relationship between Java and the World Wide Web (§1.5). • To understand the meaning of Java language specification, API, JDK, and IDE (§1.6). • To write a simple Java program (§1.7). • To display output on the console (§1.7). • To explain the basic syntax of a Java program (§1.7). • To create, compile, and run Java programs (§1.8). • To use sound Java programming style and document programs properly (§1.9). • To explain the differences between syntax errors, runtime errors, and logic errors (§1.10). 2
What is a Computer? 3 A computer consists of a CPU, memory, hard disk, floppy disk, monitor, printer, and communication devices. CPU e.g., Disk, CD, and Tape Input Devices e.g., Keyboard, Mouse e.g., Monitor, Printer Communication Devices e.g., Modem, and NIC Storage Devices Memory Output Devices Bus
CPU CPU e.g., Disk, CD, and Tape Input Devices e.g., Keyboard, Mouse e.g., Monitor, Printer Communication Devices e.g., Modem, and NIC Storage Devices Memory Output Devices Bus 4 The central processing unit (CPU) is the brain of a computer. It retrieves instructions from memory and executes them. The unit of measurement of clock speed is the hertz (Hz), with 1 hertz equaling 1 pulse per second. In the 1990s, computers measured clock speed in megahertz (MHz), but CPU speed has been improving continuously; the clock speed of a computer is now usually stated in gigahertz (GHz). Intel’s newest processors run at about 3 GHz.
Memory CPU e.g., Disk, CD, and Tape Input Devices e.g., Keyboard, Mouse e.g., Monitor, Printer Communication Devices e.g., Modem, and NIC Storage Devices Memory Output Devices Bus 5 Memory is to store data and program instructions for CPU to execute. A memory unit is an ordered sequence of bytes, each holds eight bits. A program and its data must be brought to memory before they can be executed. A memory byte is never empty, but its initial content may be meaningless to your program. The current content of a memory byte is lost whenever new information is placed in it.
How Data is Stored? Data of various kinds, such as numbers, characters, and strings, are encoded as a series of bits (zeros and ones). Computers use zeros and ones because digital devices have two stable states, which are referred to as zero and one by convention. The programmers need not to be concerned about the encoding and decoding of data, which is performed automatically by the system based on the encoding scheme. The encoding scheme varies. For example, character ‘J’ is represented by 01001010 in one byte. A small number such as three can be stored in a single byte. If computer needs to store a large number that cannot fit into a single byte, it uses a number of adjacent bytes. No two data can share or split a same byte. A byte is the minimum storage unit. 6 . . . 2000 2001 2002 2003 2004 . . . 01001010 01100001 01110110 01100001 00000011 Memory content Memory address Encoding for character ‘J’ Encoding for character ‘a’ Encoding for character ‘v’ Encoding for character ‘a’ Encoding for number 3
Storage Devices CPU e.g., Disk, CD, and Tape Input Devices e.g., Keyboard, Mouse e.g., Monitor, Printer Communication Devices e.g., Modem, and NIC Storage Devices Memory Output Devices Bus 7 Memory is volatile, because information is lost when the power is off. Programs and data are permanently stored on storage devices and are moved to memory when the computer actually uses them. There are three main types of storage devices: Disk drives (hard disks), CD drives (CD-R and CD-RW), and USB flash drives.
Output Devices: Monitor CPU e.g., Disk, CD, and Tape Input Devices e.g., Keyboard, Mouse e.g., Monitor, Printer Communication Devices e.g., Modem, and NIC Storage Devices Memory Output Devices Bus 8 The monitor displays information (text and graphics). The resolution and dot pitch determine the quality of the display.
Monitor Resolution and Dot Pitch 9 The screen resolution specifies the number of pixels in horizontal and vertical dimensions of the display device. Pixels (short for “picture elements”) are tiny dots that form an image on the screen. A common resolution for a 17-inch screen, for example, is 1,024 pixels wide and 768 pixels high. The resolution can be set manually. The higher the resolution, the sharper and clearer the image is. resolution The dot pitch is the amount of space between pixels, measured in millimeters. The smaller the dot pitch, the sharper the display. dot pitch
Communication Devices CPU e.g., Disk, CD, and Tape Input Devices e.g., Keyboard, Mouse e.g., Monitor, Printer Communication Devices e.g., Modem, and NIC Storage Devices Memory Output Devices Bus 10 A regular modem uses a phone line and can transfer data in a speed up to 56,000 bps (bits per second). A DSL (digital subscriber line) also uses a phone line and can transfer data in a speed 20 times faster than a regular modem. A cable modem uses the TV cable line maintained by the cable company. A cable modem is as fast as a DSL. Network interface card (NIC) is a device to connect a computer to a local area network (LAN). The LAN is commonly used in business, universities, and government organizations. A high-speed NIC, called 1000BaseT, can transfer data at 1000 mbps (million bits per second).
Programs Computer programs, known as software, are instructions to the computer. You tell a computer what to do through programs. Without programs, a computer is an empty machine. Computers do not understand human languages, so you need to use computer languages to communicate with them. Programs are written using programming languages. 11
Programming Languages Machine Language Assembly Language High-Level Language 12 Machine language is a set of primitive instructions built into every computer. The instructions are in the form of binary code, so you have to enter binary codes for various instructions. Program with native machine language is a tedious process. Moreover the programs are highly difficult to read and modify. For example, to add two numbers, you might write an instruction in binary like this: 1101101010011010
Programming Languages Machine Language Assembly Language High-Level Language 13 Assembly languages were developed to make programming easy. Since the computer cannot understand assembly language, however, a program called assembler is used to convert assembly language programs into machine code. For example, to add two numbers, you might write an instruction in assembly code like this: ADDF3 R1, R2, R3
Programming Languages Machine Language Assembly Language High-Level Language 14 The high-level languages are English-like and easy to learn and program. For example, the following is a high-level language statement that computes the area of a circle with radius 5: area = 5 * 5 * 3.1415;
Popular High-Level Languages 15 Language Description Ada BASIC C C++ C# COBOL FORTRAN Java Pascal Python Visual Basic Named for Ada Lovelace, who worked on mechanical general-purpose computers. The Ada language was developed for the Department of Defense and is used mainly in defense projects. Beginner’s All-purpose Symbolic Instruction Code. It was designed to be learned and used easily by beginners. Developed at Bell Laboratories. C combines the power of an assembly language with the ease of use and portability of a high-level language. C++ is an object-oriented language, based on C. Pronounced “C Sharp.” It is a hybrid of Java and C++ and was developed by Microsoft. COmmon Business Oriented Language. Used for business applications. FORmula TRANslation. Popular for scientific and mathematical applications. Developed by Sun Microsystems, now part of Oracle. It is widely used for developing platform- independent Internet applications. Named for Blaise Pascal, who pioneered calculating machines in the seventeenth century. It is a simple, structured, general-purpose language primarily for teaching programming. A simple general-purpose scripting language good for writing short programs. Visual Basic was developed by Microsoft and it enables the programmers to rapidly develop graphical user interfaces.
Interpreting/Compiling Source Code A program written in a high-level language is called a source program or source code. Because a computer cannot understand a source program, a source program must be translated into machine code for execution. The translation can be done using another programming tool called an interpreter or a compiler. 16
Interpreting Source Code An interpreter reads one statement from the source code, translates it to the machine code or virtual machine code, and then executes it right away, as shown in the following figure. Note that a statement from the source code may be translated into several machine instructions. 17
Compiling Source Code A compiler translates the entire source code into a machine-code file, and the machine-code file is then executed, as shown in the following figure. 18
Operating Systems The operating system (OS) is a program that manages and controls a computer’s activities. The popular operating systems for general-purpose computers are Microsoft Windows, Mac OS, and Linux. Application programs, such as a Web browser or a word processor, cannot run unless an operating system is installed and running on the computer. 19
Why Java? 20 The answer is that Java enables users to develop and deploy applications on the Internet for servers, desktop computers, and small hand-held devices. The future of computing is being profoundly influenced by the Internet, and Java promises to remain a big part of that future. Java is the Internet programming language. Java is a general purpose programming language. Java is the Internet programming language.
Java, Web, and Beyond • Java can be used to develop standalone applications. • Java can be used to develop applications running from a browser. • Java can also be used to develop applications for hand-held devices. • Java can be used to develop applications for Web servers. 21
Java’s History The history of Java is very interesting. Java was originally designed for interactive television, but it was too advanced technology for the digital cable television industry at the time. The history of Java starts with the Green Team. Java team members (also known as Green Team), initiated this project to develop a language for digital devices such as set-top boxes, televisions, etc. However, it was best suited for internet programming. Later, Java technology was incorporated by Netscape. The principles for creating Java programming were "Simple, Robust, Portable, Platform- independent, Secured, High Performance, Multithreaded, Architecture Neutral, Object-Oriented, Interpreted, and Dynamic". Java was developed by James Gosling, who is known as the father of Java, in 1995. James Gosling and his team members started the project in the early '90s. James Gosling - founder of java 22
Java’s History Currently, Java is used in internet programming, mobile devices, games, e-business solutions, etc. Following are given significant points that describe the history of Java. 1) James Gosling, Mike Sheridan, and Patrick Naughton initiated the Java language project in June 1991. The small team of sun engineers called Green Team. 2) Initially it was designed for small, embedded systems in electronic appliances like set- top boxes. 3) Firstly, it was called "Greentalk" by James Gosling, and the file extension was .gt. 4) After that, it was called Oak and was developed as a part of the Green project. 23
Java’s History Why Java was named as "Oak"? Java History from Oak to Java 5) Why Oak? Oak is a symbol of strength and chosen as a national tree of many countries like the U.S.A., France, Germany, Romania, etc. 6) In 1995, Oak was renamed as "Java" because it was already a trademark by Oak Technologies. Why Java Programming named "Java"? 7) Why had they chose the name Java for Java language? The team gathered to choose a new name. The suggested words were "dynamic", "revolutionary", "Silk", "jolt", "DNA", etc. They wanted something that reflected the essence of the technology: revolutionary, dynamic, lively, cool, unique, and easy to spell, and fun to say. According to James Gosling, "Java was one of the top choices along with Silk". Since Java was so unique, most of the team members preferred Java than other names. 24
Java’s History 8) Java is an island in Indonesia where the first coffee was produced (called Java coffee). It is a kind of espresso bean. Java name was chosen by James Gosling while having a cup of coffee nearby his office. 9) Notice that Java is just a name, not an acronym. 10) Initially developed by James Gosling at Sun Microsystems (which is now a subsidiary of Oracle Corporation) and released in 1995. 11) In 1995, Time magazine called Java one of the Ten Best Products of 1995. 12) JDK 1.0 was released on January 23, 1996. After the first release of Java, there have been many additional features added to the language. Now Java is being used in Windows applications, Web applications, enterprise applications, mobile applications, cards, etc. Each new version adds new features in Java. 25
Characteristics of Java • Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic 26
Characteristics of Java • Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic 27 Java is partially modeled on C++, but greatly simplified and improved. Some people refer to Java as "C++--" because it is like C++ but with more functionality and fewer negative aspects.
Characteristics of Java • Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic 28 Java is inherently object-oriented. Although many object-oriented languages began strictly as procedural languages, Java was designed from the start to be object-oriented. Object-oriented programming (OOP) is a popular programming approach that is replacing traditional procedural programming techniques. One of the central issues in software development is how to reuse code. Object- oriented programming provides great flexibility, modularity, clarity, and reusability through encapsulation, inheritance, and polymorphism.
Characteristics of Java • Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic 29 Distributed computing involves several computers working together on a network. Java is designed to make distributed computing easy. Since networking capability is inherently integrated into Java, writing network programs is like sending and receiving data to and from a file.
Characteristics of Java • Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic 30 You need an interpreter to run Java programs. The programs are compiled into the Java Virtual Machine code called bytecode. The bytecode is machine- independent and can run on any machine that has a Java interpreter, which is part of the Java Virtual Machine (JVM).
Characteristics of Java • Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic 31 Java compilers can detect many problems that would first show up at execution time in other languages. Java has eliminated certain types of error- prone programming constructs found in other languages. Java has a runtime exception-handling feature to provide programming support for robustness.
Characteristics of Java • Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic 32 Java implements several security mechanisms to protect your system against harm caused by stray programs.
Characteristics of Java • Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic 33 Write once, run anywhere With a Java Virtual Machine (JVM), you can write one program that will run on any platform.
Characteristics of Java • Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic 34 Because Java is architecture neutral, Java programs are portable. They can be run on any platform without being recompiled.
Characteristics of Java • Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic 35 Java’s performance Because Java is architecture neutral, Java programs are portable. They can be run on any platform without being recompiled.
Characteristics of Java • Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic 36 Multithread programming is smoothly integrated in Java, whereas in other languages you have to call procedures specific to the operating system to enable multithreading.
Characteristics of Java • Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic 37 Java was designed to adapt to an evolving environment. New code can be loaded on the fly without recompilation. There is no need for developers to create, and for users to install, major new software versions. New features can be incorporated transparently as needed.
JDK Versions 38 Version Date JDK Beta 1995 JDK 1.0 January 23, 1996[40] JDK 1.1 February 19, 1997 J2SE 1.2 December 8, 1998 J2SE 1.3 May 8, 2000 J2SE 1.4 February 6, 2002 J2SE 5.0 September 30, 2004 Java SE 6 December 11, 2006 Java SE 7 July 28, 2011 Java SE 8 (LTS) March 18, 2014 Java SE 9 September 21, 2017 Java SE 10 March 20, 2018 Java SE 11 (LTS) September 25, 2018[41] Java SE 12 March 19, 2019 Java SE 13 September 17, 2019 Java SE 14 March 17, 2020 Java SE 15 September 15, 2020[42] Java SE 16 March 16, 2021 Java SE 17 (LTS) September 14, 2021 Java SE 18 March 22, 2022 Java SE 19 September 20, 2022 Java SE 20 March 21, 2023 Java SE 21 (LTS) September 19, 2023 [43]
JDK Editions • Java Standard Edition (J2SE) • J2SE can be used to develop client-side standalone applications or applets. • Java Enterprise Edition (J2EE) • J2EE can be used to develop server-side applications such as Java servlets, Java ServerPages, and Java ServerFaces. • Java Micro Edition (J2ME). • J2ME can be used to develop applications for mobile devices such as cell phones. This book uses J2SE to introduce Java programming. 39
Popular Java IDEs • NetBeans • Eclipse • JetBrains IDEA 40
A Simple Java Program // This program prints Welcome to Java! public class Welcome { public static void main(String[] args) { System.out.println("Welcome to Java!"); } } 41 Listing 1.1 Welcome
Creating and Editing Using NotePad To use NotePad, type notepad Welcome.java from the DOS prompt. 42
Creating and Editing Using WordPad To use WordPad, type write Welcome.java from the DOS prompt. 43
Creating, Compiling, and Running Programs 44
Compiling Java Source Code You can port a source program to any machine with appropriate compilers. The source program must be recompiled, however, because the object program can only run on a specific machine. Nowadays computers are networked to work together. Java was designed to run object programs on any platform. With Java, you write the program once, and compile the source program into a special type of object code, known as bytecode. The bytecode can then run on any computer with a Java Virtual Machine, as shown below. Java Virtual Machine is a software that interprets Java bytecode. 45
Trace a Program Execution 46 // This program prints Welcome to Java! public class Welcome { public static void main(String[] args) { System.out.println("Welcome to Java!"); } } Enter main method
Trace a Program Execution 47 // This program prints Welcome to Java! public class Welcome { public static void main(String[] args) { System.out.println("Welcome to Java!"); } } Execute statement
Trace a Program Execution 48 // This program prints Welcome to Java! public class Welcome { public static void main(String[] args) { System.out.println("Welcome to Java!"); } } print a message to the console
Two More Simple Examples 49 WelcomeWithThreeMessages ComputeExpression
Anatomy of a Java Program • Class name • Main method • Statements • Statement terminator • Reserved words • Comments • Blocks 50
Class Name Every Java program must have at least one class. Each class has a name. By convention, class names start with an uppercase letter. In this example, the class name is Welcome. 51 // This program prints Welcome to Java! public class Welcome { public static void main(String[] args) { System.out.println("Welcome to Java!"); } }
Main Method Line 2 defines the main method. In order to run a class, the class must contain a method named main. The program is executed from the main method. 52 // This program prints Welcome to Java! public class Welcome { public static void main(String[] args) { System.out.println("Welcome to Java!"); } }
Statement A statement represents an action or a sequence of actions. The statement System.out.println("Welcome to Java!") in the program in Listing 1.1 is a statement to display the greeting "Welcome to Java!“. 53 // This program prints Welcome to Java! public class Welcome { public static void main(String[] args) { System.out.println("Welcome to Java!"); } }
Statement Terminator 54 // This program prints Welcome to Java! public class Welcome { public static void main(String[] args) { System.out.println("Welcome to Java!"); } } Every statement in Java ends with a semicolon (;).
Reserved words Reserved words or keywords are words that have a specific meaning to the compiler and cannot be used for other purposes in the program. For example, when the compiler sees the word class, it understands that the word after class is the name for the class. 55 // This program prints Welcome to Java! public class Welcome { public static void main(String[] args) { System.out.println("Welcome to Java!"); } }
Blocks 56 A pair of braces in a program forms a block that groups components of a program. public class Test { public static void main(String[] args) { System.out.println("Welcome to Java!"); } } Class block Method block
Special Symbols 57 Character Name Description {} () [] // " " ; Opening and closing braces Opening and closing parentheses Opening and closing brackets Double slashes Opening and closing quotation marks Semicolon Denotes a block to enclose statements. Used with methods. Denotes an array. Precedes a comment line. Enclosing a string (i.e., sequence of characters). Marks the end of a statement.
{ … } 58 // This program prints Welcome to Java! public class Welcome { public static void main(String[] args) { System.out.println("Welcome to Java!"); } }
( … ) 59 // This program prints Welcome to Java! public class Welcome { public static void main(String[] args) { System.out.println("Welcome to Java!"); } }
; 60 // This program prints Welcome to Java! public class Welcome { public static void main(String[] args) { System.out.println("Welcome to Java!"); } }
// … 61 // This program prints Welcome to Java! public class Welcome { public static void main(String[] args) { System.out.println("Welcome to Java!"); } }
" … " 62 // This program prints Welcome to Java! public class Welcome { public static void main(String[] args) { System.out.println("Welcome to Java!"); } }
Programming Style and Documentation •Appropriate Comments •Naming Conventions •Proper Indentation and Spacing Lines •Block Styles 63
Appropriate Comments Include a summary at the beginning of the program to explain what the program does, its key features, its supporting data structures, and any unique techniques it uses. Include your name, class section, instructor, date, and a brief description at the beginning of the program. 64
Naming Conventions • Choose meaningful and descriptive names. • Class names: • Capitalize the first letter of each word in the name. For example, the class name ComputeExpression. 65
Proper Indentation and Spacing • Indentation • Indent two spaces. • Spacing • Use blank line to separate segments of the code. 66
Block Styles Use end-of-line style for braces. 67 public class Test { public static void main(String[] args) { System.out.println("Block Styles"); } } public class Test { public static void main(String[] args) { System.out.println("Block Styles"); } } End-of-line style Next-line style
Programming Errors • Syntax Errors • Detected by the compiler • Runtime Errors • Causes the program to abort • Logic Errors • Produces incorrect result 68
Syntax Errors public class ShowSyntaxErrors { public static main(String[] args) { System.out.println("Welcome to Java); } } 69 ShowSyntaxErrors
Runtime Errors public class ShowRuntimeErrors { public static void main(String[] args) { System.out.println(1 / 0); } } 70 ShowRuntimeErrors
Logic Errors public class ShowLogicErrors { public static void main(String[] args) { System.out.println("Celsius 35 is Fahrenheit degree "); System.out.println((9 / 5) * 35 + 32); } } 71 ShowLogicErrors

More Related Content

PPT
intro to c programming
byEmmanuel Alimpolos
 
PPT
introduction to computers PROGRAMS jva.ppt
byiloveyoukika
 
PPT
Chapter 1 introduction to Computers programs, and JAVA
byAhsirYu
 
PPT
Introduction to computer programs and java
byhoneymacagubang
 
PPT
microemulsions microemulsions microemulsions microemulsions
byAhmadHashlamon
 
PPT
Java™ (OOP) - Chapter 1: "Introduction to Computers, Programs, and Java"
byGouda Mando
 
PPT
intoduction to Computer programming java learn for more chapter contact salma...
bySyed Shah
 
PPT
01slide.ppt
byPuteriNursyawatiAzzu
 
intro to c programming
byEmmanuel Alimpolos
 
introduction to computers PROGRAMS jva.ppt
byiloveyoukika
 
Chapter 1 introduction to Computers programs, and JAVA
byAhsirYu
 
Introduction to computer programs and java
byhoneymacagubang
 
microemulsions microemulsions microemulsions microemulsions
byAhmadHashlamon
 
Java™ (OOP) - Chapter 1: "Introduction to Computers, Programs, and Java"
byGouda Mando
 
intoduction to Computer programming java learn for more chapter contact salma...
bySyed Shah
 
01slide.ppt
byPuteriNursyawatiAzzu
 

Similar to Chapter 01 Java Programming Basic Java IDE JAVA INTELLIEJ

PPT
Introduction to Computers, Programs, and Java
bynaimanighat
 
PPT
Introduction To Computer and Java
byPRN USM
 
PPT
C 1
byguest8be6bb5
 
PPTX
Lecture 1 introduction to_computersb(2)
byxterribad
 
PDF
Supplementary Reading 01 - Introduction to computers, programs and java.pdf
byAshirHussain6
 
PPT
Eo gaddis java_chapter_01_5e
byGina Bullock
 
PPT
Eo gaddis java_chapter_01_5e
byGina Bullock
 
PPT
01slide
byMohamed_FMN
 
PPT
Introduction to Java Programming Language
byKarwan Mustafa Kareem
 
PPT
JavaYDL1
byTerry Yoast
 
PPT
java object oriented introduction bravaco
bymjmansoori54
 
PPT
chapter01_java_programming_object_oriented
bymjmansoori54
 
PPT
Java Software Solution Chapter 1: Computer Systems Chapter 1: Computer Systems
byNirviVashishtha
 
PPTX
Computer Systems (JSA).pptx
byssuserb58d2d
 
PPT
slides01.ppt
byRahul926331
 
ODP
Java 101 @ chattahoochee
byDeanna Riddlespur
 
PPT
CISY 105 Chapter 1
byJackie Marshall
 
PPT
01slide
byDorothea Chaffin
 
PPT
slides01.ppt
byCyberWisdom1
 
PDF
Computer Systems.pdf
byssuserb58d2d
 
Introduction to Computers, Programs, and Java
bynaimanighat
 
Introduction To Computer and Java
byPRN USM
 
C 1
byguest8be6bb5
 
Lecture 1 introduction to_computersb(2)
byxterribad
 
Supplementary Reading 01 - Introduction to computers, programs and java.pdf
byAshirHussain6
 
Eo gaddis java_chapter_01_5e
byGina Bullock
 
Eo gaddis java_chapter_01_5e
byGina Bullock
 
01slide
byMohamed_FMN
 
Introduction to Java Programming Language
byKarwan Mustafa Kareem
 
JavaYDL1
byTerry Yoast
 
java object oriented introduction bravaco
bymjmansoori54
 
chapter01_java_programming_object_oriented
bymjmansoori54
 
Java Software Solution Chapter 1: Computer Systems Chapter 1: Computer Systems
byNirviVashishtha
 
Computer Systems (JSA).pptx
byssuserb58d2d
 
slides01.ppt
byRahul926331
 
Java 101 @ chattahoochee
byDeanna Riddlespur
 
CISY 105 Chapter 1
byJackie Marshall
 
01slide
byDorothea Chaffin
 
slides01.ppt
byCyberWisdom1
 
Computer Systems.pdf
byssuserb58d2d
 

Recently uploaded

PDF
18ECL76_LAB MANUAL_UPDATED_2022 scheme.pdf
bykavana86600
 
PDF
kubernets: Kubernetes (often abbreviated as K8s) is an open-source platform f...
bysafaetulahasan1
 
PPTX
an overview to software engineering.pptx
by1111287
 
PDF
Back to the Future - A look back at Agile Engineering Practices and their Fut...
byKaizenko
 
PDF
What is Surface Mount Technology (SMT).pdf
bysproworkstech
 
PDF
2nd International Conference on AI, Machine Learning and Data Science (AIMDS ...
byIJDKP
 
PDF
From Lab to Launch Building a Career Beyond Academia
byYunyao Li
 
PDF
Drone Supported by modular optical systems
bymkevinfahlevi445
 
PPTX
MET 305 MOD 5.pptx-ENTERPRISE RESOURCE PLANNING
byVinayB68
 
PDF
Request for Information - #10547 CBTC
bymdrodriguez7
 
PPTX
CHAPTER 3_HYDROLOGIC STATISTICS AND FREQUENCY ANALYSIS.pptx
byp26335566
 
PPTX
LNG Basics by Choi SPE LNG Processes Introduction
byRobertWaters35
 
PPT
Bench_fitting_tool_mechanical_workshop.ppt
byhussain138524
 
PPT
Environment health and safety management sysem
byRamki40
 
PPT
P N Junction Diode Theory 1111111111.ppt
byHarshal Vaidya
 
PDF
Natural disaster resistant Building (earthquake and flood resistant)
byAshish Kumar
 
PDF
research material for reasearch scholers and main topics
byHariKrishna92507
 
PDF
Shell Chemicals Pipeline Magazine April 1989
byJohn Downs
 
PDF
Notes for Data Structures and Algorithms
byiambhaskaraiii
 
PPTX
Why Did The submarine Kursk Sink? What went wrong?
byBob Mayer
 
18ECL76_LAB MANUAL_UPDATED_2022 scheme.pdf
bykavana86600
 
kubernets: Kubernetes (often abbreviated as K8s) is an open-source platform f...
bysafaetulahasan1
 
an overview to software engineering.pptx
by1111287
 
Back to the Future - A look back at Agile Engineering Practices and their Fut...
byKaizenko
 
What is Surface Mount Technology (SMT).pdf
bysproworkstech
 
2nd International Conference on AI, Machine Learning and Data Science (AIMDS ...
byIJDKP
 
From Lab to Launch Building a Career Beyond Academia
byYunyao Li
 
Drone Supported by modular optical systems
bymkevinfahlevi445
 
MET 305 MOD 5.pptx-ENTERPRISE RESOURCE PLANNING
byVinayB68
 
Request for Information - #10547 CBTC
bymdrodriguez7
 
CHAPTER 3_HYDROLOGIC STATISTICS AND FREQUENCY ANALYSIS.pptx
byp26335566
 
LNG Basics by Choi SPE LNG Processes Introduction
byRobertWaters35
 
Bench_fitting_tool_mechanical_workshop.ppt
byhussain138524
 
Environment health and safety management sysem
byRamki40
 
P N Junction Diode Theory 1111111111.ppt
byHarshal Vaidya
 
Natural disaster resistant Building (earthquake and flood resistant)
byAshish Kumar
 
research material for reasearch scholers and main topics
byHariKrishna92507
 
Shell Chemicals Pipeline Magazine April 1989
byJohn Downs
 
Notes for Data Structures and Algorithms
byiambhaskaraiii
 
Why Did The submarine Kursk Sink? What went wrong?
byBob Mayer
 

Chapter 01 Java Programming Basic Java IDE JAVA INTELLIEJ

  • 1.
    Chapter 1 Introductionto Computers, Programs, and Java 1
  • 2.
    Objectives • To understandcomputer basics, programs, and operating systems (§§1.2–1.4). • To describe the relationship between Java and the World Wide Web (§1.5). • To understand the meaning of Java language specification, API, JDK, and IDE (§1.6). • To write a simple Java program (§1.7). • To display output on the console (§1.7). • To explain the basic syntax of a Java program (§1.7). • To create, compile, and run Java programs (§1.8). • To use sound Java programming style and document programs properly (§1.9). • To explain the differences between syntax errors, runtime errors, and logic errors (§1.10). 2
  • 3.
    What is aComputer? 3 A computer consists of a CPU, memory, hard disk, floppy disk, monitor, printer, and communication devices. CPU e.g., Disk, CD, and Tape Input Devices e.g., Keyboard, Mouse e.g., Monitor, Printer Communication Devices e.g., Modem, and NIC Storage Devices Memory Output Devices Bus
  • 4.
    CPU CPU e.g., Disk, CD, andTape Input Devices e.g., Keyboard, Mouse e.g., Monitor, Printer Communication Devices e.g., Modem, and NIC Storage Devices Memory Output Devices Bus 4 The central processing unit (CPU) is the brain of a computer. It retrieves instructions from memory and executes them. The unit of measurement of clock speed is the hertz (Hz), with 1 hertz equaling 1 pulse per second. In the 1990s, computers measured clock speed in megahertz (MHz), but CPU speed has been improving continuously; the clock speed of a computer is now usually stated in gigahertz (GHz). Intel’s newest processors run at about 3 GHz.
  • 5.
    Memory CPU e.g., Disk, CD, andTape Input Devices e.g., Keyboard, Mouse e.g., Monitor, Printer Communication Devices e.g., Modem, and NIC Storage Devices Memory Output Devices Bus 5 Memory is to store data and program instructions for CPU to execute. A memory unit is an ordered sequence of bytes, each holds eight bits. A program and its data must be brought to memory before they can be executed. A memory byte is never empty, but its initial content may be meaningless to your program. The current content of a memory byte is lost whenever new information is placed in it.
  • 6.
    How Data isStored? Data of various kinds, such as numbers, characters, and strings, are encoded as a series of bits (zeros and ones). Computers use zeros and ones because digital devices have two stable states, which are referred to as zero and one by convention. The programmers need not to be concerned about the encoding and decoding of data, which is performed automatically by the system based on the encoding scheme. The encoding scheme varies. For example, character ‘J’ is represented by 01001010 in one byte. A small number such as three can be stored in a single byte. If computer needs to store a large number that cannot fit into a single byte, it uses a number of adjacent bytes. No two data can share or split a same byte. A byte is the minimum storage unit. 6 . . . 2000 2001 2002 2003 2004 . . . 01001010 01100001 01110110 01100001 00000011 Memory content Memory address Encoding for character ‘J’ Encoding for character ‘a’ Encoding for character ‘v’ Encoding for character ‘a’ Encoding for number 3
  • 7.
    Storage Devices CPU e.g., Disk,CD, and Tape Input Devices e.g., Keyboard, Mouse e.g., Monitor, Printer Communication Devices e.g., Modem, and NIC Storage Devices Memory Output Devices Bus 7 Memory is volatile, because information is lost when the power is off. Programs and data are permanently stored on storage devices and are moved to memory when the computer actually uses them. There are three main types of storage devices: Disk drives (hard disks), CD drives (CD-R and CD-RW), and USB flash drives.
  • 8.
    Output Devices: Monitor CPU e.g.,Disk, CD, and Tape Input Devices e.g., Keyboard, Mouse e.g., Monitor, Printer Communication Devices e.g., Modem, and NIC Storage Devices Memory Output Devices Bus 8 The monitor displays information (text and graphics). The resolution and dot pitch determine the quality of the display.
  • 9.
    Monitor Resolution andDot Pitch 9 The screen resolution specifies the number of pixels in horizontal and vertical dimensions of the display device. Pixels (short for “picture elements”) are tiny dots that form an image on the screen. A common resolution for a 17-inch screen, for example, is 1,024 pixels wide and 768 pixels high. The resolution can be set manually. The higher the resolution, the sharper and clearer the image is. resolution The dot pitch is the amount of space between pixels, measured in millimeters. The smaller the dot pitch, the sharper the display. dot pitch
  • 10.
    Communication Devices CPU e.g., Disk,CD, and Tape Input Devices e.g., Keyboard, Mouse e.g., Monitor, Printer Communication Devices e.g., Modem, and NIC Storage Devices Memory Output Devices Bus 10 A regular modem uses a phone line and can transfer data in a speed up to 56,000 bps (bits per second). A DSL (digital subscriber line) also uses a phone line and can transfer data in a speed 20 times faster than a regular modem. A cable modem uses the TV cable line maintained by the cable company. A cable modem is as fast as a DSL. Network interface card (NIC) is a device to connect a computer to a local area network (LAN). The LAN is commonly used in business, universities, and government organizations. A high-speed NIC, called 1000BaseT, can transfer data at 1000 mbps (million bits per second).
  • 11.
    Programs Computer programs, knownas software, are instructions to the computer. You tell a computer what to do through programs. Without programs, a computer is an empty machine. Computers do not understand human languages, so you need to use computer languages to communicate with them. Programs are written using programming languages. 11
  • 12.
    Programming Languages Machine LanguageAssembly Language High-Level Language 12 Machine language is a set of primitive instructions built into every computer. The instructions are in the form of binary code, so you have to enter binary codes for various instructions. Program with native machine language is a tedious process. Moreover the programs are highly difficult to read and modify. For example, to add two numbers, you might write an instruction in binary like this: 1101101010011010
  • 13.
    Programming Languages Machine LanguageAssembly Language High-Level Language 13 Assembly languages were developed to make programming easy. Since the computer cannot understand assembly language, however, a program called assembler is used to convert assembly language programs into machine code. For example, to add two numbers, you might write an instruction in assembly code like this: ADDF3 R1, R2, R3
  • 14.
    Programming Languages Machine LanguageAssembly Language High-Level Language 14 The high-level languages are English-like and easy to learn and program. For example, the following is a high-level language statement that computes the area of a circle with radius 5: area = 5 * 5 * 3.1415;
  • 15.
    Popular High-Level Languages 15 LanguageDescription Ada BASIC C C++ C# COBOL FORTRAN Java Pascal Python Visual Basic Named for Ada Lovelace, who worked on mechanical general-purpose computers. The Ada language was developed for the Department of Defense and is used mainly in defense projects. Beginner’s All-purpose Symbolic Instruction Code. It was designed to be learned and used easily by beginners. Developed at Bell Laboratories. C combines the power of an assembly language with the ease of use and portability of a high-level language. C++ is an object-oriented language, based on C. Pronounced “C Sharp.” It is a hybrid of Java and C++ and was developed by Microsoft. COmmon Business Oriented Language. Used for business applications. FORmula TRANslation. Popular for scientific and mathematical applications. Developed by Sun Microsystems, now part of Oracle. It is widely used for developing platform- independent Internet applications. Named for Blaise Pascal, who pioneered calculating machines in the seventeenth century. It is a simple, structured, general-purpose language primarily for teaching programming. A simple general-purpose scripting language good for writing short programs. Visual Basic was developed by Microsoft and it enables the programmers to rapidly develop graphical user interfaces.
  • 16.
    Interpreting/Compiling Source Code Aprogram written in a high-level language is called a source program or source code. Because a computer cannot understand a source program, a source program must be translated into machine code for execution. The translation can be done using another programming tool called an interpreter or a compiler. 16
  • 17.
    Interpreting Source Code Aninterpreter reads one statement from the source code, translates it to the machine code or virtual machine code, and then executes it right away, as shown in the following figure. Note that a statement from the source code may be translated into several machine instructions. 17
  • 18.
    Compiling Source Code Acompiler translates the entire source code into a machine-code file, and the machine-code file is then executed, as shown in the following figure. 18
  • 19.
    Operating Systems The operatingsystem (OS) is a program that manages and controls a computer’s activities. The popular operating systems for general-purpose computers are Microsoft Windows, Mac OS, and Linux. Application programs, such as a Web browser or a word processor, cannot run unless an operating system is installed and running on the computer. 19
  • 20.
    Why Java? 20 The answeris that Java enables users to develop and deploy applications on the Internet for servers, desktop computers, and small hand-held devices. The future of computing is being profoundly influenced by the Internet, and Java promises to remain a big part of that future. Java is the Internet programming language. Java is a general purpose programming language. Java is the Internet programming language.
  • 21.
    Java, Web, andBeyond • Java can be used to develop standalone applications. • Java can be used to develop applications running from a browser. • Java can also be used to develop applications for hand-held devices. • Java can be used to develop applications for Web servers. 21
  • 22.
    Java’s History The historyof Java is very interesting. Java was originally designed for interactive television, but it was too advanced technology for the digital cable television industry at the time. The history of Java starts with the Green Team. Java team members (also known as Green Team), initiated this project to develop a language for digital devices such as set-top boxes, televisions, etc. However, it was best suited for internet programming. Later, Java technology was incorporated by Netscape. The principles for creating Java programming were "Simple, Robust, Portable, Platform- independent, Secured, High Performance, Multithreaded, Architecture Neutral, Object-Oriented, Interpreted, and Dynamic". Java was developed by James Gosling, who is known as the father of Java, in 1995. James Gosling and his team members started the project in the early '90s. James Gosling - founder of java 22
  • 23.
    Java’s History Currently, Javais used in internet programming, mobile devices, games, e-business solutions, etc. Following are given significant points that describe the history of Java. 1) James Gosling, Mike Sheridan, and Patrick Naughton initiated the Java language project in June 1991. The small team of sun engineers called Green Team. 2) Initially it was designed for small, embedded systems in electronic appliances like set- top boxes. 3) Firstly, it was called "Greentalk" by James Gosling, and the file extension was .gt. 4) After that, it was called Oak and was developed as a part of the Green project. 23
  • 24.
    Java’s History Why Javawas named as "Oak"? Java History from Oak to Java 5) Why Oak? Oak is a symbol of strength and chosen as a national tree of many countries like the U.S.A., France, Germany, Romania, etc. 6) In 1995, Oak was renamed as "Java" because it was already a trademark by Oak Technologies. Why Java Programming named "Java"? 7) Why had they chose the name Java for Java language? The team gathered to choose a new name. The suggested words were "dynamic", "revolutionary", "Silk", "jolt", "DNA", etc. They wanted something that reflected the essence of the technology: revolutionary, dynamic, lively, cool, unique, and easy to spell, and fun to say. According to James Gosling, "Java was one of the top choices along with Silk". Since Java was so unique, most of the team members preferred Java than other names. 24
  • 25.
    Java’s History 8) Javais an island in Indonesia where the first coffee was produced (called Java coffee). It is a kind of espresso bean. Java name was chosen by James Gosling while having a cup of coffee nearby his office. 9) Notice that Java is just a name, not an acronym. 10) Initially developed by James Gosling at Sun Microsystems (which is now a subsidiary of Oracle Corporation) and released in 1995. 11) In 1995, Time magazine called Java one of the Ten Best Products of 1995. 12) JDK 1.0 was released on January 23, 1996. After the first release of Java, there have been many additional features added to the language. Now Java is being used in Windows applications, Web applications, enterprise applications, mobile applications, cards, etc. Each new version adds new features in Java. 25
  • 26.
    Characteristics of Java •Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic 26
  • 27.
    Characteristics of Java •Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic 27 Java is partially modeled on C++, but greatly simplified and improved. Some people refer to Java as "C++--" because it is like C++ but with more functionality and fewer negative aspects.
  • 28.
    Characteristics of Java •Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic 28 Java is inherently object-oriented. Although many object-oriented languages began strictly as procedural languages, Java was designed from the start to be object-oriented. Object-oriented programming (OOP) is a popular programming approach that is replacing traditional procedural programming techniques. One of the central issues in software development is how to reuse code. Object- oriented programming provides great flexibility, modularity, clarity, and reusability through encapsulation, inheritance, and polymorphism.
  • 29.
    Characteristics of Java •Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic 29 Distributed computing involves several computers working together on a network. Java is designed to make distributed computing easy. Since networking capability is inherently integrated into Java, writing network programs is like sending and receiving data to and from a file.
  • 30.
    Characteristics of Java •Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic 30 You need an interpreter to run Java programs. The programs are compiled into the Java Virtual Machine code called bytecode. The bytecode is machine- independent and can run on any machine that has a Java interpreter, which is part of the Java Virtual Machine (JVM).
  • 31.
    Characteristics of Java •Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic 31 Java compilers can detect many problems that would first show up at execution time in other languages. Java has eliminated certain types of error- prone programming constructs found in other languages. Java has a runtime exception-handling feature to provide programming support for robustness.
  • 32.
    Characteristics of Java •Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic 32 Java implements several security mechanisms to protect your system against harm caused by stray programs.
  • 33.
    Characteristics of Java •Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic 33 Write once, run anywhere With a Java Virtual Machine (JVM), you can write one program that will run on any platform.
  • 34.
    Characteristics of Java •Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic 34 Because Java is architecture neutral, Java programs are portable. They can be run on any platform without being recompiled.
  • 35.
    Characteristics of Java •Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic 35 Java’s performance Because Java is architecture neutral, Java programs are portable. They can be run on any platform without being recompiled.
  • 36.
    Characteristics of Java •Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic 36 Multithread programming is smoothly integrated in Java, whereas in other languages you have to call procedures specific to the operating system to enable multithreading.
  • 37.
    Characteristics of Java •Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic 37 Java was designed to adapt to an evolving environment. New code can be loaded on the fly without recompilation. There is no need for developers to create, and for users to install, major new software versions. New features can be incorporated transparently as needed.
  • 38.
    JDK Versions 38 Version Date JDKBeta 1995 JDK 1.0 January 23, 1996[40] JDK 1.1 February 19, 1997 J2SE 1.2 December 8, 1998 J2SE 1.3 May 8, 2000 J2SE 1.4 February 6, 2002 J2SE 5.0 September 30, 2004 Java SE 6 December 11, 2006 Java SE 7 July 28, 2011 Java SE 8 (LTS) March 18, 2014 Java SE 9 September 21, 2017 Java SE 10 March 20, 2018 Java SE 11 (LTS) September 25, 2018[41] Java SE 12 March 19, 2019 Java SE 13 September 17, 2019 Java SE 14 March 17, 2020 Java SE 15 September 15, 2020[42] Java SE 16 March 16, 2021 Java SE 17 (LTS) September 14, 2021 Java SE 18 March 22, 2022 Java SE 19 September 20, 2022 Java SE 20 March 21, 2023 Java SE 21 (LTS) September 19, 2023 [43]
  • 39.
    JDK Editions • JavaStandard Edition (J2SE) • J2SE can be used to develop client-side standalone applications or applets. • Java Enterprise Edition (J2EE) • J2EE can be used to develop server-side applications such as Java servlets, Java ServerPages, and Java ServerFaces. • Java Micro Edition (J2ME). • J2ME can be used to develop applications for mobile devices such as cell phones. This book uses J2SE to introduce Java programming. 39
  • 40.
    Popular Java IDEs •NetBeans • Eclipse • JetBrains IDEA 40
  • 41.
    A Simple JavaProgram // This program prints Welcome to Java! public class Welcome { public static void main(String[] args) { System.out.println("Welcome to Java!"); } } 41 Listing 1.1 Welcome
  • 42.
    Creating and EditingUsing NotePad To use NotePad, type notepad Welcome.java from the DOS prompt. 42
  • 43.
    Creating and EditingUsing WordPad To use WordPad, type write Welcome.java from the DOS prompt. 43
  • 44.
    Creating, Compiling, andRunning Programs 44
  • 45.
    Compiling Java SourceCode You can port a source program to any machine with appropriate compilers. The source program must be recompiled, however, because the object program can only run on a specific machine. Nowadays computers are networked to work together. Java was designed to run object programs on any platform. With Java, you write the program once, and compile the source program into a special type of object code, known as bytecode. The bytecode can then run on any computer with a Java Virtual Machine, as shown below. Java Virtual Machine is a software that interprets Java bytecode. 45
  • 46.
    Trace a ProgramExecution 46 // This program prints Welcome to Java! public class Welcome { public static void main(String[] args) { System.out.println("Welcome to Java!"); } } Enter main method
  • 47.
    Trace a ProgramExecution 47 // This program prints Welcome to Java! public class Welcome { public static void main(String[] args) { System.out.println("Welcome to Java!"); } } Execute statement
  • 48.
    Trace a ProgramExecution 48 // This program prints Welcome to Java! public class Welcome { public static void main(String[] args) { System.out.println("Welcome to Java!"); } } print a message to the console
  • 49.
    Two More SimpleExamples 49 WelcomeWithThreeMessages ComputeExpression
  • 50.
    Anatomy of aJava Program • Class name • Main method • Statements • Statement terminator • Reserved words • Comments • Blocks 50
  • 51.
    Class Name Every Javaprogram must have at least one class. Each class has a name. By convention, class names start with an uppercase letter. In this example, the class name is Welcome. 51 // This program prints Welcome to Java! public class Welcome { public static void main(String[] args) { System.out.println("Welcome to Java!"); } }
  • 52.
    Main Method Line 2defines the main method. In order to run a class, the class must contain a method named main. The program is executed from the main method. 52 // This program prints Welcome to Java! public class Welcome { public static void main(String[] args) { System.out.println("Welcome to Java!"); } }
  • 53.
    Statement A statement representsan action or a sequence of actions. The statement System.out.println("Welcome to Java!") in the program in Listing 1.1 is a statement to display the greeting "Welcome to Java!“. 53 // This program prints Welcome to Java! public class Welcome { public static void main(String[] args) { System.out.println("Welcome to Java!"); } }
  • 54.
    Statement Terminator 54 // Thisprogram prints Welcome to Java! public class Welcome { public static void main(String[] args) { System.out.println("Welcome to Java!"); } } Every statement in Java ends with a semicolon (;).
  • 55.
    Reserved words Reserved wordsor keywords are words that have a specific meaning to the compiler and cannot be used for other purposes in the program. For example, when the compiler sees the word class, it understands that the word after class is the name for the class. 55 // This program prints Welcome to Java! public class Welcome { public static void main(String[] args) { System.out.println("Welcome to Java!"); } }
  • 56.
    Blocks 56 A pair ofbraces in a program forms a block that groups components of a program. public class Test { public static void main(String[] args) { System.out.println("Welcome to Java!"); } } Class block Method block
  • 57.
    Special Symbols 57 Character NameDescription {} () [] // " " ; Opening and closing braces Opening and closing parentheses Opening and closing brackets Double slashes Opening and closing quotation marks Semicolon Denotes a block to enclose statements. Used with methods. Denotes an array. Precedes a comment line. Enclosing a string (i.e., sequence of characters). Marks the end of a statement.
  • 58.
    { … } 58 //This program prints Welcome to Java! public class Welcome { public static void main(String[] args) { System.out.println("Welcome to Java!"); } }
  • 59.
    ( … ) 59 //This program prints Welcome to Java! public class Welcome { public static void main(String[] args) { System.out.println("Welcome to Java!"); } }
  • 60.
    ; 60 // This programprints Welcome to Java! public class Welcome { public static void main(String[] args) { System.out.println("Welcome to Java!"); } }
  • 61.
    // … 61 // Thisprogram prints Welcome to Java! public class Welcome { public static void main(String[] args) { System.out.println("Welcome to Java!"); } }
  • 62.
    " … " 62 //This program prints Welcome to Java! public class Welcome { public static void main(String[] args) { System.out.println("Welcome to Java!"); } }
  • 63.
    Programming Style and Documentation •AppropriateComments •Naming Conventions •Proper Indentation and Spacing Lines •Block Styles 63
  • 64.
    Appropriate Comments Include asummary at the beginning of the program to explain what the program does, its key features, its supporting data structures, and any unique techniques it uses. Include your name, class section, instructor, date, and a brief description at the beginning of the program. 64
  • 65.
    Naming Conventions • Choosemeaningful and descriptive names. • Class names: • Capitalize the first letter of each word in the name. For example, the class name ComputeExpression. 65
  • 66.
    Proper Indentation andSpacing • Indentation • Indent two spaces. • Spacing • Use blank line to separate segments of the code. 66
  • 67.
    Block Styles Use end-of-linestyle for braces. 67 public class Test { public static void main(String[] args) { System.out.println("Block Styles"); } } public class Test { public static void main(String[] args) { System.out.println("Block Styles"); } } End-of-line style Next-line style
  • 68.
    Programming Errors • SyntaxErrors • Detected by the compiler • Runtime Errors • Causes the program to abort • Logic Errors • Produces incorrect result 68
  • 69.
    Syntax Errors public classShowSyntaxErrors { public static main(String[] args) { System.out.println("Welcome to Java); } } 69 ShowSyntaxErrors
  • 70.
    Runtime Errors public classShowRuntimeErrors { public static void main(String[] args) { System.out.println(1 / 0); } } 70 ShowRuntimeErrors
  • 71.
    Logic Errors public classShowLogicErrors { public static void main(String[] args) { System.out.println("Celsius 35 is Fahrenheit degree "); System.out.println((9 / 5) * 35 + 32); } } 71 ShowLogicErrors