public static void main(String[] args) {        String a1 = new String("a_a");        String a2 = new String("a_a");        System.out.println("a:");        System.out.println(a1 == a2);        System.out.println("-------------------------");                String b1 = "b_b";        String b2 = "b_b";        System.out.println("b:");        System.out.println(b1 == b2);        System.out.println("-------------------------");        String c = new String("c");        String c1 = c + "_c";        String c2 = "c_c";        System.out.println("c:");        System.out.println(c1 == c1.intern());        System.out.println(c1 == c2);        System.out.println(c2 == c1.intern());        System.out.println(c2 == c2.intern());        System.out.println("-------------------------");            String d = new String("d");        String d1 = d + "_d";        System.out.println(d1 == d1.intern());        String d2 = "d_d";        System.out.println("d:");        System.out.println(d1 == d2);        System.out.println("-------------------------");    }