Swing을 이용한 간단한 - 그림판 -

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.JRadioButton;
import javax.swing.JCheckBox;
import javax.swing.JButton;
import javax.swing.ButtonGroup;
import javax.swing.JPanel;
import javax.swing.JComboBox;
import java.awt.FlowLayout;
import java.awt.Canvas;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseMotionAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.*;

class GraphicTest extends JFrame implements ActionListener {
 JLabel x1L, y1L, x2L, y2L, z1L, z2L;
 JTextField x1T, y1T, x2T, y2T, z1T, z2T;
 JCheckBox fill;
 JRadioButton line, circle, rect, roundR, arc;
 JButton draw;
 DrCanvas can;
 JComboBox combo;

 int x1, y1, x2, y2, z1, z2;
 
 public GraphicTest() {
  super("간단 그림판");//setTitle("간단 그림판"); //super는 맨위쪽

  x1L = new JLabel("x1L");
  y1L = new JLabel("y1L");
  x2L = new JLabel("x2L");
  y2L = new JLabel("y2L");
  z1L = new JLabel("z1L");
  z2L = new JLabel("z2L");

  x1T = new JTextField("100",4);
  y1T = new JTextField("150",4);
  x2T = new JTextField("200",4);
  y2T = new JTextField("250",4);
  z1T = new JTextField("80",4);
  z2T = new JTextField("80",4);

  fill = new JCheckBox("채우기");

  line = new JRadioButton("선");
  circle = new JRadioButton("원");
  rect = new JRadioButton("사각형", true);
  roundR = new JRadioButton("둥근사각형");
  arc = new JRadioButton("호");

  ButtonGroup bg = new ButtonGroup();
  bg.add(line);
  bg.add(circle);
  bg.add(rect);
  bg.add(roundR);
  bg.add(arc);

  draw = new JButton("그리기");
 
  can = new DrCanvas();

  String[] color = {"빨강", "초록", "파랑", "검정", "보라"};
  combo = new JComboBox(color);

  JPanel p = new JPanel(); //FlowLayout(순서배치)    

  p.add(x1L); p.add(x1T);
  p.add(y1L); p.add(y1T);
  p.add(x2L); p.add(x2T);
  p.add(y2L); p.add(y2T);
  p.add(z1L); p.add(z1T);
  p.add(z2L); p.add(z2T);
  p.add(fill);  

  JPanel p2 = new JPanel();

  p2.add(line);
  p2.add(circle);
  p2.add(rect);
  p2.add(roundR);
  p2.add(arc);
  p2.add(combo);
  p2.add(draw);

  getContentPane().add("North", p);
  getContentPane().add("South", p2);
  getContentPane().add("Center", can);

  setBounds(500,100,600,500);
  setVisible(true);
  setDefaultCloseOperation(EXIT_ON_CLOSE);  

  //이벤트 처리
  draw.addActionListener(this);
  line.addActionListener(this);
  circle.addActionListener(this);
  rect.addActionListener(this);
  roundR.addActionListener(this);
  arc.addActionListener(this);    
  can.addMouseListener(new MouseAdapter() {
   public void mousePressed(MouseEvent e) {
    x1T.setText(String.valueOf(e.getX()));
    y1T.setText(String.valueOf(e.getY()));
    can.repaint();
   }
  });
  can.addMouseMotionListener(new MouseMotionAdapter(){
   public void mouseDragged(MouseEvent e){
    x2T.setText(String.valueOf(e.getX()));
    y2T.setText(String.valueOf(e.getY()));
    can.repaint();
   }
  });
 }//GraphicTest( )
 
 //ActionListner override
 public void actionPerformed(ActionEvent e){
   can.repaint(); //update () -> paint() 순서로 호출
 }

 class DrCanvas extends Canvas {
  public  DrCanvas() {
   this.setBackground(new Color(255,255,100)); //바탕색 -연한노랑
   setForeground(new Color(255,0,0));//글자색
  }//DrCanvas( )

  public void paint(Graphics g) {
   //좌표 얻어오기
   x1 = Integer.parseInt(x1T.getText().trim()); //trim - 앞뒤공백제거
   y1 = Integer.parseInt(y1T.getText().trim());
   x2 = Integer.parseInt(x2T.getText().trim());
   y2 = Integer.parseInt(y2T.getText().trim());
   z1 = Integer.parseInt(z1T.getText().trim());
   z2 = Integer.parseInt(z2T.getText().trim());    
   
   //색
   switch(combo.getSelectedIndex()) {
    case 0: this.setForeground(new Color (255,0,0));
     break;    
    case 1: this.setForeground(new Color (0,255,0));
     break;
    case 2: this.setForeground(new Color (0,0,255));
     break;
    case 3: this.setForeground(new Color (0,0,0));
     break;
    case 4: this.setForeground(new Color (255,0,255));
     break;
   }//switch

   int startX = x1 < x2 ? x1 : x2;
   int startY = y1 < y2 ? y1 : y2;
   int width = x1 < x2 ? x2-x1 : x1-x2;
   int height = y1 < y2 ? y2-y1 : y1-y2;

   //도형 그리기
   if(fill.isSelected()) {  //채우기 선택
    if(line.isSelected())
     g.drawLine(x1, y1, x2, y2);
    else if(circle.isSelected())
     g.fillOval(startX, startY, width, height);
    else if(rect.isSelected())
     g.fillRect(startX, startY, width, height);
    else if(roundR.isSelected())
     g.fillRoundRect(startX, startY, width, height, z1, z2);
    else if(arc.isSelected())
     g.fillArc(startX, startY, width, height, z1, z2);
   }else { //채우기 해제
    if(line.isSelected())
     g.drawLine(x1, y1, x2, y2);
    else if(circle.isSelected())
     g.drawOval(startX, startY, width, height);
    else if(rect.isSelected())
     g.drawRect(startX, startY, width, height);
    else if(roundR.isSelected())
     g.drawRoundRect(startX, startY, width, height, z1, z2);
    else if(arc.isSelected())
     g.drawArc(startX, startY, width, height, z1, z2);
   }//else  
  }//paint( )
 } //DrCanvas

 public static void main(String[] args) {
  new GraphicTest();  
 }//main( )
}