String#intern, String.intern() 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 public class StringIntern { public static void main(String[] args) { String s0 = "foo"; String s1 = "foo"; String s2 = new String("foo"); String s3 = s2.intern(); String s4 = new String("foo").intern(); String s5 = new String("s5"); System.out.println(s0==s1); System.out.println(s0==s2); System.out.println(s0==s3); System.out.println(s2==s3); System.out.println(s0==s4); System.out.println(s0==s5); } } 1 2 3 4