keytypetest.java

java程序设计 清华出版社 孙燮华老师编写的程序源代码

    //keyTypeTest.java
    import java.awt.*;
    import java.awt.event.*;
    import java.applet.Applet;
    
    public class keyTypeTest extends Applet implements KeyListener {
      String msg="Hello";
      //int X=10,Y=20;
      
      public void init(){
        //setLayout(new FlowLayout());
        addKeyListener(this);
        requestFocus();
        //setSize(500,150);
        //setVisible(true);
      }
  
      public void keyPressed(KeyEvent e){
        int key=e.getKeyCode();
        
        switch(key){
          case KeyEvent.VK_LEFT:
            msg="Left key typed";
            break;
          case KeyEvent.VK_RIGHT:
            msg="Right key typed";
            break;
          case KeyEvent.VK_UP:
            msg="Up key typed";
            break;
          case KeyEvent.VK_DOWN:
            msg="Down key typed";
            break;
        }
        repaint();
      }
      
      public void paint(Graphics g){
      	Font font=new Font("",Font.PLAIN,24);
        g.setFont(font);
        FontMetrics fontmetrics=getFontMetrics(font);
        int X=(size().width-fontmetrics.stringWidth(msg))/2;
        int Y=(size().height-fontmetrics.getHeight())/2+fontmetrics.getAscent();
        //g.drawString(text,x,y);
      	g.drawString(msg,X,Y);
      }
      public void keyTyped(KeyEvent e){repaint();}
      public void keyReleased(KeyEvent e){repaint();}
      /*
      public static void main(String args[]){
        keyTypeTest s=new keyTypeTest();
      }*/
}