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);
}
}