Calling private method inside private class inside Inner class

Question

Need to call a private method foo() of the class Inner.Private , where Private is an inner private class from the main method of the main class. The code is something like this:

public class MainClass {
    public static void main(String[] args) throws Exception {
        // Need to invoke foo() from here
        } 

    static class Inner {
        private class Private {
            private String foo() {
                return "someString";
            }
        }
    }
}

I was trying to get this using Java Reflection, but I am facing issues from this approach.

My attempt to invoke the foo() is:

        Inner innerClassObject = new Inner();
        Method method = Inner.Private.class.getDeclaredMethod("foo");
        method.setAccessible(true);
        method.invoke(innerClassObject);

But this gives a NoSuchMethodException:

Exception in thread "main" java.lang.NoSuchMethodException: 
default.MainClass$Inner$Private.foo()
    at java.lang.Class.getDeclaredMethod(Unknown Source) 

I am stuck at this point, is this achievable by Java Reflection, or any other way?

Answer 1

嗯...为什么不简单地new Inner().new Private().foo() ？

Answer 2

Why are you doing this

Inner.Private.class

Instead of

innerClassObject.getClass()

For ex:

public class Test {


private int foo(){
    System.out.println("Test"); 
    return 1;
}
public static void main(String [] args) throws InterruptedException, 
NoSuchMethodException, IllegalAccessException, IllegalArgumentException, 
InvocationTargetException
{
  Test innerClassObject = new Test();
    Method method = 
    innerClassObject.getClass().getDeclaredMethod("foo",null);
    method.setAccessible(true);
    method.invoke(innerClassObject);
}


}

Answer 3

Why waste an instantiation just to call a method as was described? You will inevitably want to save various instances for latter use as the classes develop.

public class MainClass {
    public static void main(String[] args) throws Exception {
        // Need to invoke foo() from here
        Inner inner = new Inner();
        Inner.Private pvt = inner.new Private();
        System.out.println(pvt.foo());
    }

    static class Inner {
        private class Private {
            private String foo() {
                return "someString";
            }
        }
    }
}

Prints

someString