A twisted inner class in Java

Question

The following program uses an inner class named Anonymous which itself extends its enclosing class Main.

package name;

public class Main
{
    private final String name;

    Main(String name)
    {
        this.name = name;
    }

    private String name()
    {
        return name;
    }

    private void reproduce()
    {
        new Anonymous().printName();
    }

    private class Anonymous extends Main
    {
        public Anonymous()
        {
            super("reproduce");
        }

        public void printName()
        {
            System.out.println(name());
        }
    }

    public static void main(String[] args)
    {
       new Main("main").reproduce();
    }
}

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The only statement in the main() method invokes the constructor of the outer class Main supplying a string main and just then the method reproduce() is being called.

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The reproduce method contains the statement new Anonymous().printName(); which invokes the printName() method on the Anonymous class object. The super(); constructor is supplying a new string reproduce to its enclosing super class Main.

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Accordingly, the statement within the printName method System.out.println(name()); should display the string reproduce rather than main but it always displays the string main. Why is it so?

Answer 1

Because you've declared Main.name() as private, so it's not visible as a superclass method. It is, however, visible as a method of Anonymous's enclosing class, so it is invoked on the enclosing object.

So if you declare Main.name() as public or protected, you will indeed see "reproduce". Alternatively, if you declare Anonymous as static, it no longer compiles.