public class TestString { void test1() { // TODO Auto-generated method stub String str = new String(); str = "12345"; String STR = "12345"; System.out.println(str == STR); String str_1 = str; String str_2 = null; str_2 = str; String str_3 = new String(); str_3 = str; String str_4 = new String(str); System.out.println("str:" + str); System.out.println("str_1:" + str_1); System.out.println("str == str_1:" + str == str_1); System.out.println("str_2:" + str_2); System.out.println("str == str_2:" + str == str_2); System.out.println("str_3:" + str_3); System.out.println("str == str_3:" + str == str_3); System.out.println("str_4:" + str_4); System.out.println("str == str_4:" + str == str_4); str = "2345678"; System.out.println("str:" + str); System.out.println("str_1:" + str_1); System.out.println("str == str_1:" + str == str_1); System.out.println("str_2:" + str_2); System.out.println("str == str_2:" + str == str_2); System.out.println("str_3:" + str_3); System.out.println("str == str_3:" + str == str_3); System.out.println("str_4:" + str_4); System.out.println("str == str_4:" + str == str_4); } static void test2(){//false String str = new String("123"); String str_2 = new String("123"); System.out.println( str == str_2); } static void test3(){//false String str = "123"; String str_2 = new String("123"); System.out.println( str == str_2); } static void test4(){//true String str = "123"; String str_2 = "123"; System.out.println( str == str_2); } public static void main(String[] args) { test2(); test3(); test4(); } }
总结:new 一定是深拷贝,好要继续实验