public class ReferenceCheck {
    public static void main(String[] args) {
        String s1 = new String("abc");
        String s2 = new String("abc");
        String s3 = s2;
        String s4 = "abc";

        System.out.println("s1.equals(s2) " + s1.equals(s2));
        System.out.println("s1==s2 " + (s1 == s2));
        System.out.println("s1==s3 " + (s1 == s3));
        System.out.println("s1==s4 " + (s1 == s4));
        System.out.println("s2==s3 " + (s2 == s3));
        System.out.println("s2==s3 " + (s2 == s4));
        System.out.println("s3==s4 " + (s3 == s4));
    }
}