1 import java.awt.BorderLayout;
2 import java.awt.Color;
3 import java.awt.Graphics;
4 import java.awt.GridLayout;
5 import java.awt.event.ActionEvent;
6 import java.awt.event.ActionListener;
7
8 import javax.swing.*;
9
10 public class Test_17_3 extends JFrame{
11 private final int YSTART = 20;
12 private final int VGAP = 2;
13 private final int XGAP = 2;
14 private Color myColor = Color.BLACK;
15
16 ButtonGroup group = new ButtonGroup();
17 JRadioButton jrb1 = new JRadioButton("red");
18 JRadioButton jrb2 = new JRadioButton("blue");
19 JRadioButton jrb3 = new JRadioButton("yellow");
20
21 trafficPanel tP = new trafficPanel();
22 public Test_17_3(){
23
24 JPanel jgButtons = new JPanel();
25 jgButtons.setLayout(new GridLayout(1,3));
26 jgButtons.add(jrb1);
27 jgButtons.add(jrb2);
28 jgButtons.add(jrb3);
29
30 group.add(jrb1);
31 group.add(jrb2);
32 group.add(jrb3);
33
34 setLayout(new BorderLayout());
35 add(jgButtons,BorderLayout.SOUTH);
36 add(tP,BorderLayout.CENTER);
37
38 jrb1.addActionListener(new ActionListener(){
39
40 @Override
41 public void actionPerformed(ActionEvent arg0) {
42 // TODO Auto-generated method stub
43 myColor = Color.RED;
44 tP.setColor = true;
45 repaint();
46 }
47
48 });
49 jrb2.addActionListener(new ActionListener(){
50
51 @Override
52 public void actionPerformed(ActionEvent arg0) {
53 // TODO Auto-generated method stub
54 myColor = Color.BLUE;
55 tP.setColor = true;
56 repaint();
57 }
58
59 });
60 jrb3.addActionListener(new ActionListener(){
61
62 @Override
63 public void actionPerformed(ActionEvent arg0) {
64 // TODO Auto-generated method stub
65 myColor = Color.YELLOW;
66 tP.setColor = true;
67 repaint();
68 }
69
70 });
71 }
72 public static void main(String[] args) {
73 // TODO Auto-generated method stub
74 Test_17_3 frame = new Test_17_3();
75 frame.setTitle("Test_17_3");
76 frame.setSize(300,200);
77 frame.setLocationRelativeTo(null);
78 frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
79 frame.setVisible(true);
80 }
81
82
83 class trafficPanel extends JPanel{
84 public boolean setColor = false;
85
86 protected void paintComponent(Graphics g){
87 int xCenter = getWidth()/2;
88 int yCenter = getHeight()/2;
89
90 int radius = getHeight() /6 - 5;
91 /** draw steady shape */
92 //draw rect
93 g.drawRect(xCenter -radius,YSTART, 2*radius,getHeight()-20 -VGAP);
94 //draw three circles
95 g.drawOval(xCenter - radius + XGAP, YSTART + VGAP, 2*radius -2*XGAP , 2*radius-2*XGAP);
96 g.drawOval(xCenter - radius + XGAP, YSTART + 2*radius + 2*VGAP,2*radius -2*XGAP , 2*radius-2*XGAP);
97 g.drawOval(xCenter - radius + XGAP, YSTART + 4*radius + 3*VGAP,2*radius -2*XGAP , 2*radius-2*XGAP );
98
99 if(setColor)
100 {
101 if(myColor == Color.RED)
102 {g.setColor(Color.RED); g.fillOval(xCenter - radius + XGAP, YSTART + VGAP, 2*radius -2*XGAP , 2*radius-2*XGAP);}
103 else if(myColor == Color.BLUE)
104 {g.setColor(Color.BLUE); g.fillOval(xCenter - radius + XGAP, YSTART + 2*radius + 2*VGAP,2*radius -2*XGAP , 2*radius-2*XGAP);}
105 else
106 {g.setColor(Color.YELLOW);g.fillOval(xCenter - radius + XGAP, YSTART + 4*radius + 3*VGAP,2*radius -2*XGAP , 2*radius-2*XGAP );}
107 }
108 }
109 }
110 }
