java intro.pptx.pdf

Java Program Development Steps Text Editor / IDE File.java (Text File) Java Compiler Java Interpreter Result / Output File.class (Bytecode) O n c e Everytim e

Oracle site Java Virtual Machine JRE JDK

Oracle site Java Virtual Machine Runs the java bytecode ! Does not understand java syntax and grammar That is why we compile a java program to generate the bytecode and understand the bytecodes

Oracle site JRE Provides the JVM, libraries to run java program To execute application Java Runtime Environment

Oracle site JDK Java Development Kit

WRITE YOUR FIRST JAVA PROGRAM IN NOTEPAD++

Example of java program in notepad++ 1st key word public

Example of java program in notepad++ 2 access specifiers for Java classes (not for inner classes) 1. Public public class MyFirstClass 2. Default (don’t type anything) class MyFirstClass

Example of java program in notepad++ 2nd key word Class Name of the class MyFirstClass - use to create java classes Declare all your classes with public access specifier

Example of java program in notepad++ Name of the method main Name of the variables args

IDENTIFIERS in Java represent the following: - Name of the class - Name of the method - Name of the variable Identifiers are case sensitive. Ex. MyFirstClass is different from Myfirstclass Examples of identifiers: MyFirstClass, main, args, System (class name), out (Reference Variable name) println (method name)

Identifiers Naming Rules: 1. Name must begin with a. A to Z (upper and lower case) b. _ (underscore) c. $ (dollar sign) or other currency symbol Example of valid identifiers in java EXAMCLASS examCLASS _Learners _Course $$Payment $Fee

Identifiers Naming Rules: 2. After the first character, subsequent characters may use numbers from 0 - 9 Example of valid identifiers A1Example _123Test $1Market

Identifiers Naming Rules: 3. Identifiers can’t use JAVA keywords Example of invalid identifiers public class void static

Identifiers Naming Rules: 4. Identifiers can’t use following literals: true false null

Keywords in Java abstract continue for new switch assert default goto package synchronized boolean do if private this break double implements protected throw byte else import public throws case enum instanceof return transient catch extends int short try char final interface static void class finally long strictfp volatile const float native super while const & goto: are reserved even though they are not currently used strictfp: added in JDK 1.2 assert: added in JDK 1.4 enum: added in JDK 5.0

WRITE YOUR FIRST JAVA PROGRAM IN ECLIPSE

2nd line Class definition in java must start with { opening curly bracket and end with } closing curley bracket

Main method signatures are also valid: static public void main(String[] args)[ ] { } public static void main(String. . . args)[]{ }

4 access specifiers can be applied to methods in java: - Private - Default (don’t specify anything - Protected - Public But this special main method must be declared public only 3rd line, 1st word public Example of Access specifier

3rd line, 2nd word static Means main is shared among all instances of this class

3rd line, 3rd word void Means this method does not written anything

3rd line, 4th word main - this is the name of the method - It an identifier

Method names in java are followed by (. If method takes no arguments it should end with ). Example: Public void play() But if method takes some arguments, add the arguments declarations and then add ). Example: Public void play(string sport) Round brackets ( ) is used as part of method signature

args the name of the string array parameter String arrays [ ] accespts string arrays as a parameter What are the arguments that we can pass inside the method? { opening bracket for the main method

System.out.println It prints text included/enclosed in double quote “ “ Displays the text in screen console 4th line in eclipse program

5th line Type sysout and press Ctrl + Space, Auto-complete feature will write whole System.out.println statement

To delete one line, place the cursor anywhere on the line and press Ctrl + D To delete multiple lines, select multiple lines and press Ctrl + D

System.out.println () System.out.print(“ "); Add a new line character takes you to the next line Keeps the cursor to the current line Does not go to print to the next line

Semi colon ; Semicolon is use to end the statement You can use multiple semicolon System.out.println("A");;;; And it will not give you an error

Closing bracket of main method Closing bracket of the class Opening bracket of the class Opening bracket of the main

java intro.pptx.pdf

More Related Content

Similar to java intro.pptx.pdf

Recently uploaded

java intro.pptx.pdf