// sample program to demonstrate equals vs == and interning of strings

public class StringFun {
    public static void main(String[] args) {
        // all of these strings will be .equals to each other
        // the question is when are they == to each other
        String s1 = "hello";
        String s2 = "hello";
        String s3 = "he" + "llo";
        // these first 3 strings are all computed at compile
        // time, so the compiler is able to intern them
        System.out.println(s1 == s2);
        System.out.println(s1 == s3);
                
        // what if there is a variable involved?  Then it is
        // computed at runtime and no interning takes place
        String sub = "he";
        String s4 = sub + "llo";
        System.out.println(s1 == s4);

        // by making the "sub" string final, interning again
        // takes place
        final String sub2 = "he";
        String s5 = sub2 + "llo";
        System.out.println(s1 == s5);
                
        // you can intern strings yourself to be able to use
        // == comparisons
        s4 = s4.intern();
        System.out.println(s1 == s4);
    }
}