16.19
1 import java.awt.Graphics; 2 import java.awt.event.*; 3 import javax.swing.*; 4 5 public class Test_16_19 extends JFrame{ 6 7 public Test_16_19(){ 8 JP jp1 = new JP(); 9 add(jp1); 10 } 11 public static void main(String[] args) { 12 // TODO Auto-generated method stub 13 Test_16_19 frame = new Test_16_19(); 14 frame.setSize(300,300); 15 frame.setTitle("Test_16_19"); 16 frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 17 frame.setLocationRelativeTo(null); // Center the frame 18 frame.setVisible(true); 19 } 20 static class JP extends JPanel{ 21 private int x_distance, x_co; 22 private int y_distance, y_co; 23 private double distance; 24 private String str=""; 25 public JP(){ 26 addMouseMotionListener(new MouseMotionAdapter(){ 27 public void mouseMoved(MouseEvent e){ 28 x_co = e.getX();y_co = e.getY(); 29 distance =Math.sqrt(x_distance*x_distance+y_distance*y_distance); 30 31 if(distance>50) 32 str = "out of the circle"; 33 else str = "in the circle"; 34 repaint(); 35 } 36 }); 37 } 38 protected void paintComponent(Graphics g){ 39 int xCenter = getWidth()/2; 40 int yCenter = getHeight()/2; 41 x_distance = Math.abs(x_co - xCenter); 42 y_distance = Math.abs(y_co - yCenter); 43 44 super.paintComponent(g); 45 g.drawOval(xCenter -50, yCenter - 50, 100, 100); 46 g.drawString(str, x_co, y_co); 47 g.drawString(x_co+","+y_co, x_co, y_co-10); 48 // System.out.println(getX() + " " + getY()); 49 } 50 } 51 }
效果图：
