java嵌套类内部和外部引用等于

public class Outer2 {

 Outer2(){
    System.out.println("Calling Outer2 constructor");
    System.out.println(this.getClass().getName() + ": Inner class reference is " + this);
    System.out.println(Outer2.this + ": Outer class reference is " + Outer2.this);
 }

 class Inner1 extends Outer2 {
    Inner1() {
        System.out.println("Calling Inner1 constructor");
        System.out.println(this.getClass().getName() + ": Inner class reference is " + this);
        System.out.println(Outer2.this + ": Outer class reference is " + Outer2.this);
    }
}

 class Inner2 extends Inner1 {
    Inner2() {
        System.out.println("Calling Inner2 constructor");
        System.out.println(this.getClass().getName() + ": Inner class reference is " + this);
        System.out.println(Outer2.this + ": Outer class reference is " + Outer2.this);
    }
}

 public static void main(String[] args) {
    new Outer2().new Inner2();
}

}

Can someone explain why the above code gives the following output:

有人可以解释为什么上面的代码给出了以下输出:

 Calling Outer2 constructor
 outer2.Outer2: Inner class reference is outer2.Outer2@15db9742
 outer2.Outer2@15db9742: Outer class reference is outer2.Outer2@15db9742
 Calling Outer2 constructor
 outer2.Outer2$Inner2: Inner class reference is 
 outer2.Outer2$Inner2@6d06d69c
 outer2.Outer2$Inner2@6d06d69c: Outer class reference is 
 outer2.Outer2$Inner2@6d06d69c
 Calling Inner1 constructor
 outer2.Outer2$Inner2: Inner class reference is 
 outer2.Outer2$Inner2@6d06d69c
 outer2.Outer2@15db9742: Outer class reference is outer2.Outer2@15db9742
 Calling Inner2 constructor
 outer2.Outer2$Inner2: Inner class reference is 
 outer2.Outer2$Inner2@6d06d69c
 outer2.Outer2@15db9742: Outer class reference is outer2.Outer2@15db9742

I'm interested in why the inner and outer class reference equals when calling Outer2 supertype constructor second time?

我很感兴趣为什么内部和外部类引用在第二次调用Outer2超类型构造函数时相等?

1 个解决方案

#1

In the Outer2 constructor, you're not in any inner class of Outer2. So, for the compiler, the line

在Outer2构造函数中,您不在Outer2的任何内部类中。所以,对于编译器来说,这一行

System.out.println(Outer2.this + ": Outer class reference is " + Outer2.this);

is strictly equivalent to

严格等同于

System.out.println(Outer2.this + ": Outer class reference is " + this);

So the value of this , is printed twice. And since this is actually a reference to the Inner2 object being created, it prints outer2.Outer2$Inner2@6d06d69c.

所以它的价值打印两次。由于这实际上是对正在创建的Inner2对象的引用,因此它打印outer2.Outer2$Inner2@6d06d69c。

#1