String equality

    String s1 = "hello!";
    String s2 = "hello!";
    String s3 = "hello!".intern();
    String s4 = new String("hello!");
    String s5 = "lo";

    System.out.println("s1 == s2 " + (s1 == s2)); // true
    System.out.println("s1 == s3 " + (s1 == s3)); // true
    System.out.println("s1 == s4 " + (s1 == s4)); // false
    System.out.println("s1 == s4.intern() " + (s1 == s4.intern())); // true
    System.out.println("s1 == \"hel\" + \"lo!\": " + (s1 == "hel" + "lo!")); // true
    System.out.println("s1 == \"hel\" + s5: " + (s1 == "hel" + s5)); // false