零基础新手，关于GUI布局管理的

零基础新手求助，关于GUI布局管理的
package elevator;

import java.awt.*;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.Insets;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Scanner;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingConstants;

public class ElevatorFrame{
public static void main(String[] args){
 new Interface("Elevator",300,300,1200,800);
}
}

class Interface extends Frame{
private Panel ele1,ele2,ele3,ele4,ele5;
Interface(String s,int x,int y,int w,int h){
super(s);
setLayout(null);
ele1 = new Panel(null); ele2 = new Panel(null);
ele3 = new Panel(null); ele4 = new Panel(null);

ele1.setBounds(0,0,w/5,h);
ele2.setBounds(w/5,0,w/5,h);
ele3.setBounds(2*w/5,0,w/5,h);
ele4.setBounds(3*w/5,0,w/5,h);
ele5.setBounds(4*w/5,0,w/5,h);

ele1.setBackground(Color.CYAN);
ele2.setBackground(Color.CYAN);
ele3.setBackground(Color.CYAN);
ele4.setBackground(Color.CYAN);
ele5.setBackground(Color.CYAN);
add(ele1);add(ele2);add(ele3);add(ele4);add(ele5);
setBounds(x,y,w,h);
setVisible(true);
}
}

运行时出现：
Exception in thread "main" java.lang.NullPointerException
at elevator.Interface.<init>(ElevatorFrame.java:44)
at elevator.ElevatorFrame.main(ElevatorFrame.java:22)

求助各位大大，哪里出错了？要怎样改？谢谢了
------解决思路----------------------
ele5表示不服，前四个你都初始化了就它你不管了....