Java GUI程序问题

Question

我是新来的，希望我能正确提交，因为我知道内容应该一致。无论如何我正在为ATM模拟器制作一个GUI程序，并且遇到添加麻烦（mainPanel（））;错误是找不到符号   symbol：方法mainPanel（）

location：class ATMProject.AtmApplication

代码如下：

package atmproject;

/**
 *
 * 
 * 9/10/2015
 */
import javax.swing.*;
import java.awt.*;

public class ATMProject extends JFrame {
    //create frame/Constructor
    static final int WIDTH = 300, HEIGHT = 200;
    public ATMProject(){
        super("ATMProject");
        setFrame(WIDTH,HEIGHT);
    }

    public ATMProject(String title){
        super(title);
        setFrame(WIDTH,HEIGHT);
    }

    public ATMProject(String title, int width, int height){
        super(title);
        setFrame(width,height);

    }

    public void display(){
         setVisible(true);

    }

    private void setFrame (int width, int height){
        setSize(width, height);
        setLocation(null);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    }




    public JFrame atmFrame;

    public void myFrame(){

        atmFrame = new JFrame();
        atmFrame.setVisible(true);
        atmFrame.setSize(300,200);
        atmFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);


    }



    //create buttons
    private JButton withdrawal = new JButton("Withdrawal");
    private JButton deposit = new JButton("Deposit");
    private JButton transferTo = new JButton("Transfer To");
    private JButton balance = new JButton("Balance");

    //set text field
    private JTextField output = new JTextField("");

    //set radio buttons

    //panel construction class
    public void ATMPanel (){


        setLayout (new BorderLayout());
        setBackground (Color.lightGray);

        //main panel
        JPanel mainPanel = new JPanel();
        mainPanel.setLayout(new GridLayout (3,2,5,5));

        //result text color????
        output.setEditable(false);
        //add buttons to panel
        mainPanel.add(withdrawal);
        mainPanel.add(deposit);
        mainPanel.add(transferTo);
        mainPanel.add(balance);
        //radio buttons!!!!!!!!!
        //mainPanel.add(balance);
        //mainPanel.add(balance);
        //output
        mainPanel.add(output);

        add(mainPanel, BorderLayout.CENTER);
        mainPanel.setVisible(true);
        atmFrame.add(mainPanel);






    }

    public class AtmApplication extends ATMProject{
        public AtmApplication() {
            super("ATM Machine", 300, 200);
            add(mainPanel());

        }

    }





    public static void main(String[] args) {
        ATMProject test = new ATMProject();
        add(new mainPanel());



    }

}