String intern method

String a = "ab";
String b = new String("ab");
System.out.println(a == b);
System.out.println(a.equals(b));
System.out.println(b.intern() == a);
System.out.println(a.intern() == b);

Print result:
false
true
true
false

new String will not look for the existing string in the String constant. The string.intern() method finds equal strings in the character constant pool.