Java string , string buffer and wrapper class

Java string , string buffer and wrapper class

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  Java String classprovides a lot of methods to perform operations on string such as compare(), concat(), equals(), split(), length(), replace(), compareTo(), intern(), substring() etc. String The CharSequence interface is used to represent the sequence of characters. String, StringBuffer and StringBuilder classes implement it. It means, we can create strings in java by using these three classes. public class StringExample{ public static void main(String args[]){ String s1="java";//creating string by java string literal char ch[]={'s','t','r','i','n','g','s'}; String s2=new String(ch);//converting char array to string String s3=new String("example");//creating java string by new keyword System.out.println(s1); System.out.println(s2); System.out.println(s3); }} Output : java strings example
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  Java StringBuffer classis used to create mutable (modifiable) string. The StringBuffer class in java is same as String class except it is mutable i.e. it can be changed. Java StringBuffer class is thread-safe i.e. multiple threads cannot access it simultaneously. So it is safe and will result in an order. Java StringBuffer class Constructor Description StringBuffer() creates an empty string buffer with the initial capacity of 16. StringBuffer(String str) creates a string buffer with the specified string. StringBuffer(int capacity) creates an empty string buffer with the specified capacity as length. Important Constructors of StringBuffer class
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  StringBuffer examples Some ofthe methods of stringbuffer class is as follows: 1. StringBuffer append() method The append() method concatenates the given argument with this string. class StringBufferExample{ public static void main(String args[]){ StringBuffer sb=new StringBuffer("Hello "); sb.append("Java");//now original string is changed System.out.println(sb);//prints Hello Java } }
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  2) StringBuffer insert()method The insert() method inserts the given string with this string at the given position. class StringBufferExample2{ public static void main(String args[]){ StringBuffer sb=new StringBuffer("Hello "); sb.insert(1,"Java");//now original string is changed System.out.println(sb);//prints HJavaello } } 3) StringBuffer replace() method The replace() method replaces the given string from the specified beginIndex and endIndex. class StringBufferExample3{ public static void main(String args[]){ StringBuffer sb=new StringBuffer("Hello"); sb.replace(1,3,"Java"); System.out.println(sb);//prints HJavalo } } Conti.
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  4) StringBuffer delete()method The delete() method deletes the string from the specified beginIndex to endIndex. class StringBufferExample4{ public static void main(String args[]){ StringBuffer sb=new StringBuffer("Hello"); sb.delete(1,3); System.out.println(sb);//prints Hlo } } 5) StringBuffer reverse() method The reverse() method of StringBuffer class reverses the current string. class StringBufferExample5{ public static void main(String args[]){ StringBuffer sb=new StringBuffer("Hello"); sb.reverse(); System.out.println(sb);//prints olleH } }
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  Wrapper class inJava Wrapper class in java provides the mechanism to convert primitive into object and object into primitive. The eight classes of java.lang package are known as wrapper classes in java. The list of eight wrapper classes are given below: Primitive type Wrapper class boolean Boolean int Integer byte Byte short Short char Charcter long Long float Float double Double
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  Wrapper class Example:Primitive to Wrapper public class WrapperExample1{ public static void main(String args[]){ //convert primitive into object type int a=20; Integer i=Integer.valueOf(a); //converting int into Integer System.out.println(“printing as primitive type "+a); System.out.println(“printing as object: ” + i) }} Output: 20 20
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  Wrapper class Example:Primitive to Wrapper public class WrapperExample2{ public static void main(String args[]){ //Converting Integer to int Integer a=new Integer(3); int i=a.intValue(); //converting Integer to int System.out.println(“printing as object "+a); System.out.println(“printing as primitive type ” + i) }} Output: 3 3 3