Integer a = 127;
Integer b = 127;
System.out.println( a == b);    //true

Integer c = 128;
Integer d = 128;
System.out.println( c == d);    // false

Integer e = new Integer(127);
Integer f = new Integer(127);
System.out.println( e == f);   //false

String  g = "a1";
String  h = "a1";
System.out.println( g == h );  //true

String  j = "a1";
String  k = "a" + 1;
System.out.println( j == k );  // true

String  l = new String( "a1" );
String  m = new String( "a1" );
System.out.println( l == m );  //false