Java: String and StringBuffer

package learningExtra;

public class StringandStringBuffer {


public static void main(String[] args) {
String st1=new String("sumit");
String st2=new String("Neha");
String st3=new String("sumit");
st1.concat("raut");
System.out.println(st1); //#########Prints sumit because String class is immutable

StringBuffer sb1=new StringBuffer("Amit");
StringBuffer sb2=new StringBuffer("Amit");
sb1.append("raut");
System.out.println(sb1); //#########Prints Amitraut because StringBuffer class is not immutable


// #Note only has following way StringBuffer sb=new StringBuffer("yourtext")
System.out.println("#####Below For String#######");
System.out.println(st1==st3);       //    ==>false
System.out.println(st1.equals(st3));// true


System.out.println("#####Below For StringBuffer#######");
System.out.println(sb1==sb2);       //====>false
System.out.println(sb1.equals(sb2));//====> false   .equals to in StringBuffer is not overridden for Content Comparison.
                                                     //Hence does address comparison


System.out.println("#####Below For compareTo#######");
String test1=new String("Software");
String test2=new String("Testing");
String test3=new String("Software");
System.out.println(test1.compareTo(test2)); //-1   unicode of test1<unicode of test2
System.out.println(test1.compareTo(test3)); //0   unicode of test1=test3
System.out.println(test2.compareTo(test1)); //1    unicode of test2>unicode of test1
}

}