以下代码的运行结果是哪一项。 ( ) public class J_Intern { public static void main(String args[ ]) { String s1 = "123456"; String s2 = "123456"; String s3 = "123" + "456"; String a0 = "123"; String s4 = a0 + "456"; String s5 = new String("123456"); String s6 = s5.intern( ); System.out.println("s2" + ((s2==s1) ? "==" : "!=") +"s1"); System.out.println("s3" + ((s3==s1) ? "==" : "!=") +"s1"); System.out.println("s4" + ((s4==s1) ? "==" : "!=") +"s1"); System.out.println("s5" + ((s5==s1) ? "==" : "!=") +"s1"); System.out.println("s6" + ((s6==s1) ? "==" : "!=") +"s1"); }}