Question

我写了下面的代码来使用箭头键移动一个矩形，但是当我按下键时，jframe窗口上没有发生任何移动。我搜索了很多关于这个，但无济于事。我只看到一个寡妇画出的矩形而没有别的。请帮助这是我的代码

import javax.swing.JFrame;

public class Main 
{

    public static void main(String args[])
{

JFrame window=new JFrame();
    window.setSize(640,480);
    window.setTitle("window");
    window.setVisible(true);
    window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    drawingComponent DC=new drawingComponent();
    window.add(DC);

}

}


import java.awt.Graphics2D;
import java.awt.Graphics;
import java.awt.Rectangle;
import java.awt.Event;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JComponent;
import javax.swing.Timer;
public class drawingComponent extends JComponent implements ActionListener,KeyListener
{
    Timer t=new Timer(50,this);//moving after 5 milliseconds
int x=0,y=0,vx=0,vy=0;
    public drawingComponent()
    {

            t.start();
    addKeyListener(this);

    setFocusable(true);

    setFocusTraversalKeysEnabled(false);

}
public void paintComponent(Graphics g)
{

    Graphics2D g2=(Graphics2D) g;
    Rectangle rect1=new Rectangle(x,y,100,30);
    g2.draw(rect1);

}
public void actionPerformed(ActionEvent e) //inbuilt fncn f actionListener(interface) which needs to be created
{
    x+=vx;      //changing values
    y+=vy;

    repaint();          //inbuilt fncn to repeat the paintComponent method
}

public void keyPressed(KeyEvent e)
{

    System.out.println("ewbkw");
    int code=e.getKeyCode();
    if(code==KeyEvent.VK_UP)
    { vx=0; vy=-2;repaint(); }
    if(code==KeyEvent.VK_DOWN)
        { vx=0; vy=2; repaint(); }
    if(code==KeyEvent.VK_LEFT)
        {vy=0; vx=-2; repaint(); }
    if(code==KeyEvent.VK_RIGHT)
        {vy=0; vx=2; repaint();}
}
public void keyTyped(KeyEvent e)
{}
public void keyReleased(KeyEvent e)
{}
}

Answer 1

您可以尝试使用ArrayList添加按下ArrayList的密钥，然后在发布后将其删除。

您也可以使用

repaint();

在您的所有if语句

之后

public void keyPressed(KeyEvent e)
{
    System.out.println("ewbkw");

    int code = e.getKeyCode();

    if(code==KeyEvent.VK_UP){
        vx=0; vy=-2;
    }

    if(code==KeyEvent.VK_DOWN){
        vx=0; vy=2;
    }

    if(code==KeyEvent.VK_LEFT){
        vy=0; vx=-2;
    }

    if(code==KeyEvent.VK_RIGHT){
        vy=0; vx=2;
    }

    repaint();
}

如果您只对if语句使用一个语句，那么您将不需要使用Curly Brackets {}

if (true)
    System.out.println("Example of no brackets");
else
    System.out.println("Not even for an IF ELSE");

你也可能不需要定时器。但我可能是错的。

使用箭头键移动矩形

1 个答案: