Java中Object对象的hashCode方法和String对象的hashCode

class A{}public class TestMain {    public static void main(String[] args) {        A a1 = new A();        A a2 = new A();        String str1 = "abc";        String str2 = new String("abc");        System.out.println(str1 == str2);        System.out.println(str1.equals(str2));        System.out.println(str1);        System.out.println(str2);        System.out.println(str1.hashCode());        System.out.println(str2.hashCode());        //Hash码是标志对象的唯一值，Hash码相同的对象是同一对象        System.out.println(a1.equals(a2));        System.out.println(a1 == a2);        System.out.println(a1);        System.out.println(a2);        System.out.println(a1.hashCode());        System.out.println(a2.hashCode());    }}