Convert classes that extends with JPanel into JPanel

Question

What i want do is,

I have a class named 'TestPanel' that extends from JPanel. and want to make it draggable by a method. But method returns JPanel type and shows this error when compiling.

cannot convert from JPanel to testpanel

Method cannot be make for return 'TestPanel' type because i hope to make more classes like testpanel. Here is the RegisterAsDraggable method that returns JPanel.

    public static JPanel RegisterAsDraggable(){
        final JPanel panel = new JPanel();
        ...
        return panel;
    }

Here is the class that extends from JPanel.

public class testpanel extends JPanel {
    JLabel titlelabel;

    public testpanel(){
        initsettings();

        GroupLayout layout = new GroupLayout(this);
        this.setLayout(layout);
        ...
    }
}

And here is my main class.

public class HelloWorld extends JFrame {

    public HelloWorld(){
        initcomponent();
        ...
    }

    private void initcomponent() {
        testpanel tstpan = DragsExternal.RegisterAsDraggable();
        ...
    }

    public static void main(String[] args){
        new HelloWorld().setVisible(true);
    }
}

I removed some of codes because for make this not too long.

-- Edit --

I tried to do that by casting testpanel into JPanel.( Accouding to your answers). But it showed this error

Exception in thread "main" java.lang.ClassCastException: javax.swing.JPanel cannot be cast to testpanel

Can anyone help? Please excuse my English.

Answer 1

Please do yourself a favor: Learn and follow Java coding standards.

You just need to make one change:

 JPanel tstpan = DragsExternal.RegisterAsDraggable();

or

 testpanel tstpan = (testpanel) DragsExternal.RegisterAsDraggable();

Answer 2

you need to cast the Jpanel to a testpanel

private void initcomponent() {
    testpanel tstpan = (testpanel) DragsExternal.RegisterAsDraggable();
    ...
}