Question

java小程序出错！！！实现键盘方向键移动不了，帮我看看代码那里错，谢谢！！

import java.awt.*;
import java.awt.Graphics;
import java.applet.Applet;
import java.awt.event.*;
import java.awt.event.KeyEvent;

public class TestKey extends Applet implements KeyListener{

int x,y;
public void init() {
addKeyListener(this);
x=30;
y=30;
}

public void keyTyped(KeyEvent e) {

if(e.getKeyCode()==e.VK_UP)
y+=10;
else if(e.getKeyCode()==e.VK_DOWN)
y-=10;
else if(e.getKeyCode()==e.VK_LEFT)
x+=10;
else if
(e.getKeyCode()==e.VK_RIGHT)
x-=10;

}

public void paint(Graphics g){
g.drawString("java程序设计", x, y );
}
public void keyReleased( KeyEvent e ) { }
public void keyPressed( KeyEvent e ) { }
}
编译是可以的，就是运行那个htm程序的时候只显示那段“java程序设计”，但要按方向键却移动不了，大侠帮我看看下，谢谢！！

按照一楼的建议加了repaint（），看结果还是移动不了,不知道哪里错了~~晕

Answer 1

import java.awt.Graphics;
import java.applet.Applet;
import java.awt.event.*;
import java.awt.event.KeyEvent;

public class TestKey extends Applet implements KeyListener {

int x=30, y=30;

public void init() {
addKeyListener(this);
}

public void keyTyped(KeyEvent e) {

}

public void paint(Graphics g) {
g.drawString("java程序设计", x, y);
}

public void keyReleased(KeyEvent e) {

}

public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == e.VK_DOWN)
y += 10;
else if (e.getKeyCode() == e.VK_UP)
y -= 10;
else if (e.getKeyCode() == e.VK_RIGHT)
x += 10;
else if (e.getKeyCode() == e.VK_LEFT)
x -= 10;
repaint();
}
}
改成这样试试

Answer 2

你木有repaint（）啊

public void keyTyped(KeyEvent e) {

if(e.getKeyCode()==e.VK_UP) {
y+=10;
repaint();
}
else if(e.getKeyCode()==e.VK_DOWN) {
y-=10;
repaint();
}
else if(e.getKeyCode()==e.VK_LEFT) {
x+=10;
repaint();
}
else if
(e.getKeyCode()==e.VK_RIGHT) {
x-=10;
repaint();
}

}

Answer 3

你这个按下之后没代码了，所以检测到了按键操作，图像也不能移动。
这样做：
检测到按键按下以后，再重新画图，根据新坐标。然后再repaint()