碰到的有意思的代码

    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("-------------------------");
    }