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Q) Explain about String handling ?



 A)
->A string is a sequence of characters which is represented as an object in java.
->In java.long.package three classes objects represent a string
1) String
2) StringBuffer
3) StringBuilder  - it is introduced in JDK 1.5

->The StringBuffer methods are for thread sake so they are synchronized. But when they are synchronized the performance is decreased. So, that’s why sun micro system recommended when we need StringBuffer then go for StringBuilder. But where there is need of Thread then go for StringBuffer. Methods of StringBuilder are non-synchronize methods of StringBuffer are synchronized that is only difference.
->java.long.String class represents immutable (non modifiable) Strings.
->java.long.StringBuffer and java.long.StringBuilder represent mutable strings.
->mutable means the modification done on the same object.
->immutable means the modifications done on another object.

Ex:

class stringtest {

       public static void main(String[] args) {
             
              String s= new String("hello "); // immutable string created.
              String str= s.concat("how are you");
              System.out.println(s);
              System.out.println(str);
             
              StringBuffer sb= new StringBuffer("hello"); //mutable string created.
              sb.append("how are you");
              System.out.println(sb);
             
              StringBuilder sbuilder= new StringBuilder("hello"); //mutable string created
              sbuilder.append("how are you");
              System.out.println(sbuilder);
       }

}

Output:
hello
hello how are you
hellohow are you
hellohow are you

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