如何访问在Java中使用它的唯一类的私有嵌套类对象

Question

I have a base class in Java. In that class I want to create a private class and I want to access the object of that private class in the base class. How can I do that?

Thanks in advance!

Answer 1

You can access an object of an inner class by creating it and remembering its reference. Just like an instance of any other class.

public enum Outer {;
    private static class Nested {
        private Nested() { }
    }

    public static Object getNested() {
        return new Nested();
    }
}

public class Main {
    public static void main(String... args)  {
        System.out.println("I have an "+ Outer.newNested());
    }
}

prints

I have an Outer$Nested@3f0ef90c

---

A good example is from Arrays. This creates an instance of a private nested class which implements a public interface which makes it useful.

public static <T> List<T> asList(T... a) {
return new ArrayList<T>(a);
}

/**
 * @serial include
 */
private static class ArrayList<E> extends AbstractList<E>
implements RandomAccess, java.io.Serializable
{

Answer 2

Do you mean this:

class Test {

    private Inner inner = new Inner();  

    private class Inner {
        public void foo() {}
    }

    // later somewhere
    public void bar() {
        inner.foo();
    }      
}

Answer 3

PrivateClass c = new PrivateClass();
c.getSomeObject(); //??

You can use the above code in your base class; provided the private class is an inner class of your base class.

Answer 4

class Test {

    private class Inner {
        public void foo() {
            System.out.println("vsahdashdashd");
        }
    }

    // later somewhere
    public void bar() {
        new Inner().foo();
    }      
}
class javaapplication9 extends Test
{
      public static void main(String[] args) {
        Test inner = new Test();  
        inner.bar();
      }
you can access private member from this type.