接口的两个完全相同的实现给出不同的.hashCode（）结果

Question

I've an interface like this-

public interface myInterface {
    String getMyString();
}

And two implementations like this-

class test implements myInterface {

        @Override
        public String getMyString() {
            return "1,2";
        }
    }

class test2 implements myInterface {

        @Override
        public String getMyString() {
            return "1,2";
        }
    }

When I create new instnaces of these two clasess and do .hashCode I get different values for hashCode. Why so?

test test = new test();
test2 test2 = new test2();

System.out.println(test.hashCode());
System.out.println(test2.hashCode());

Answer 1

如果三个注释没有提示您问题所在，则您有不同的类，您没有重写hashCode方法，而是实际上使用接口的方法使您的类具有相同的哈希码。

Answer 2

因为它们是两个不同的对象，所以如果要使它们相同，则需要覆盖哈希码方法。

Answer 3

Quoted from JavaDoc of Object#hashCode()

As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the JavaTM programming language.)

Unless you have overridden hashCode() , what described above will be the default behavior.