public class Viewer
{
 public static void main(String[] args)
 {
  new myframe();
//creating main jframe instance
 }
}

/////////////////////////////////////////////////////////////////////////////

import java.awt.Color;
import java.awt.Container;
import java.awt.Graphics;
import javax.swing.JPanel;


public class myDrawboard extends JPanel{


 public myDrawboard()
 {
  setBackground(Color.BLACK);
 }
 
 public void paintComponent(Graphics g){
  
 }

 public int countItem() {
  // TODO Auto-generated method stub
  return 0;
 }

 public void removeBall() {
  // TODO Auto-generated method stub
  
 }

 public void additem(int parseInt, String string) {
  // TODO Auto-generated method stub
  
 }
 

}

/////////////////////////////////////////////////////////////////////////

import java.awt.*;

import javax.swing.*;
import java.awt.event.*;
public class myframe extends JFrame
{
 Container c;
 
 JPanel panel;
 JButton addbutton,removebutton;
 JLabel counter,ballsize;
 JTextField size_input;
 JComboBox cb;
 
 buttonListener handle;
 myDrawboard myboard;
 
 public myframe()
 {
  super("BOUNCING ITEM Simulator");
  c=getContentPane(); 
 
  c.setLayout(new BorderLayout());
  

  size_input=new JTextField(2);
  counter=new JLabel("ITEM Count:  ");
  ballsize=new JLabel("ITEM Size:  ");
  
  addbutton=new JButton("Add");
  removebutton=new JButton("Remove");
  
  cb=new JComboBox();
  cb.addItem("Ball");
  cb.addItem("Box");
  
  handle=new buttonListener();

  addbutton.addActionListener(handle);
  removebutton.addActionListener(handle);
  
  
  panel=new JPanel();
  panel.add(ballsize);
  panel.add(size_input);
  panel.add(addbutton);
  panel.add(removebutton);
  panel.add(counter);
  
  panel.add(cb);
  
  c.add(new Panel(),BorderLayout.NORTH);
  c.add(new Panel(),BorderLayout.EAST);
  c.add(new Panel(),BorderLayout.WEST);
  
  myboard=new myDrawboard();
  
  c.add(myboard,BorderLayout.CENTER);
  c.add(panel,BorderLayout.SOUTH);
  setSize(640,480);
  setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  setVisible(true);
 
 }
 
 public class buttonListener implements ActionListener
 {
  int i;
  public void actionPerformed(ActionEvent ae)
  {
   if(ae.getSource()==addbutton)
   {
    if(!size_input.getText().equals(""))
    {
     try{
       myboard.additem(Integer.parseInt(size_input.getText()),cb.getSelectedItem().toString());
       counter.setText("ITEM Count:"+myboard.countItem());
      }
     catch(NumberFormatException e)
     {
      System.out.println(e);
      JOptionPane.showMessageDialog(null,"Enter only numbers!","Invalid Input",JOptionPane.INFORMATION_MESSAGE);
     }
    }
    else
    {
     JOptionPane.showMessageDialog(null,"Enter the ITEM size!","Input needed",JOptionPane.INFORMATION_MESSAGE);
    }
   }
   
   if(ae.getSource()==removebutton)
   {
    myboard.removeBall();
    counter.setText("ITEM Count:"+myboard.countItem());
   }
  }
 }
}
//////////////////////////////////////////////////////////////////////////////////

 

paintComponent에서 drawRect같은거 쓰면 사각형 잘생기는데

뒤에 정가운데에 검은색 배경 박고 싶은데 적용이 안되 ㅠ.ㅠ

아무리 봐도 맞는거 같은데 적용이 안되 ㅠ.ㅠ.