为什么匿名类不能访问私有方法和变量？

Question

package demo;

class Child{
    private static int a=50;
    public void fin() {
        System.out.println("hello");
    }
    private void fly() {
        System.out.println("lol");
    }
}

public class Hello {
    public static void main(String[] args) 
    {  
        Child c=new Child() {

            public void f() {
                System.out.println("sorry"+a);
            }
            public void fin() {
                System.out.println("hello");

            }

        };
        c.fin();

}}

Above is the code of java my point is why cant private methods and variables be called in anonymous class as I had read somewhere that an anonymous class can access all members of enclosed class.
https://www.baeldung.com/java-anonymous-classes go checkout which specifies that each member of the anonymous class can access all members of the enclosed class.

Answer 1

There is a confusion in that code about "inner class" and "anonymous class".

Notice you have 3 classes there:

• Child
• Hello
• Hello$1 : An anonymous class declared inside of Hello and whose parent is Child

The confusion in the code is about the latter:

• Hello$1 is a subclass of Child
• Hello$1 is an inner class of Hello

This means:

• Hello$1 cannot access private fields from Child , as subclasses cannot access private elements of their super classes
• Hello$1 can access private fields from Hello , as anonymous inner classes can access private elements of their enclosing classes

Check it more clearly in this code:

class Child {
    private int a = 50;
}

public class Hello {
    private int b = 60;

    public void f() 
    {  
        Child c = new Child() {
            public void f() {
                // System.out.println("a = " + a); // This won't compile
                System.out.println("b = " + b); // This compiles OK
            }
        };
    }
}

Answer 2

The fact that you're anonymously overriding class is inconsequential to the situation. A class cannot access its parent's private members. If you want to access the parent's members you could define them with protected or default visibility.

Answer 3

i had read somewhere that anonymous class can access all members of enclosed class.

I assume you mean of enclosing class and yes. However Child is not the enclosing class it's the parent class. The enclosing class in your case would be Hello.class and if you add to it private static int a; ie:

public class Hello {
    private static int a = 40;
...

It will work.