Java让图像在屏幕外重新出现

Question

我对这个问题有点困惑。

基本上，我有一个汽车图像，一旦它在 x 轴上从屏幕上消失，我需要返回到起点。我以为我已经通过 checkOFFscreen 修复了它，但它不起作用，所以我很糟糕，并要求提供一些有关如何解决此问题的指导。

Mainpanel.java

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.util.ArrayList;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.Timer;


public class MainPanel extends JPanel {

    Player myPlayer;
    Player myOtherPlayer;
    private int WIDTH = 1000;
    private int HEIGHT = 1000;
    private int WALLWIDTH = 100;
    private int WALLHEIGHT = 100;
    private ArrayList<Wall> walls = new ArrayList<Wall>();


    Timer myTimer = new Timer(500, new timerListener());    
    JLabel myTimeLabel;
    int time =1;



    public MainPanel()
    {
        setPreferredSize(new Dimension(WIDTH,HEIGHT));
        JLabel myLabel= new JLabel ("Game ends once 30 seconds is receahed:");
        myLabel.setFont(new Font("Serif", Font.BOLD,32));
        myLabel.setForeground(Color.WHITE);
        myTimeLabel= new JLabel (Integer.toString(time));
        myTimeLabel.setFont(new Font("Serif", Font.BOLD,32));
        myTimer.start();

        add(myLabel);
        add(myTimeLabel);
        myPlayer = new Player(0,100, "toad.png", KeyEvent.VK_UP, KeyEvent.VK_DOWN, KeyEvent.VK_LEFT, KeyEvent.VK_RIGHT,this, 50, 38);
        myOtherPlayer = new Player(200,200, "toad.png", KeyEvent.VK_W, KeyEvent.VK_S, KeyEvent.VK_A, KeyEvent.VK_D,this, 50, 38);
        createWalls();
    }

    public ArrayList<Wall> getWalls() {
        return walls;
    }

    public void createWalls()
    {
        int j = 0;
        for(int i = 0; i < HEIGHT/WALLHEIGHT; i++)
        {
            for(int k = 0; k < WIDTH/WALLWIDTH; k++)
            {
                if(i == 0 || i == (HEIGHT/WALLHEIGHT-1))
                {
                    walls.add(new Wall(k*WALLWIDTH,j,"road.png", 100, 100));
                }

            }
            j+=WALLHEIGHT;
        }
    }


    private class timerListener implements ActionListener
    {


        public void actionPerformed(ActionEvent e) {
            time++;
            myTimeLabel.setText(Integer.toString(time));
            myTimeLabel.setForeground(Color.WHITE);
            if(time >= 30)
            {
                myTimer.stop();
            }
            repaint();
        }

    }


    public void paintComponent(Graphics page)
    {
        super.paintComponent(page);

        page.drawImage(myPlayer.getImageIcon().getImage(), myPlayer.getX(), myPlayer.getY(), null);
        page.drawImage(myOtherPlayer.getImageIcon().getImage(), myOtherPlayer.getX(), myOtherPlayer.getY(), null);

        for(int i = 0; i < walls.size(); i++)
        {
            page.drawImage(walls.get(i).getImageIcon().getImage(), walls.get(i).getX(), walls.get(i).getY(), null);


        }

        page.setFont(new Font("Arial", Font.PLAIN,32)); 
        page.drawString("Player 1 Score: " + myPlayer.getScore(), 100, 800);
        page.drawString("Player 2 Score: " + myOtherPlayer.getScore(), 100, 850);


        if(time > 30)
        {
            page.drawString("GAME OVER", WIDTH/2-100, HEIGHT/2);
            JOptionPane.showMessageDialog(null, "Please enter your email");

            }

    }
}

Player.java

import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.util.ArrayList;

import javax.swing.ImageIcon;

public class Player extends GameObject implements KeyListener{


    private int Up;
    private int Down;
    private int Left;
    private int Right;

    private MainPanel myPanel;
    private Movement myMovement = new Movement();

    private int score = 0;

    public Player(int x, int y, String imagePath, int Up, int Down, int Left, int Right, MainPanel myPanel, int HEIGHT, int WIDTH)
    {
        super(x,y,imagePath, HEIGHT, WIDTH);

        this.Up = Up;
        this.Down = Down;
        this.Left = Left;
        this.Right = Right;
        this.myPanel = myPanel;
        myPanel.addKeyListener(this);
        myPanel.setFocusable(true);
         checkOffScreen();

    }

    public int getX() {
        return x;
    }

    public void setX(int x) {
        this.x = x;
    }

    public int getY() {
        return y;
    }

    public void setY(int y) {
        this.y = y;
    }

    public void checkOffScreen(){
        if (x >=1050){
            x=0;
        }
    }



    public int getScore()
    {
        return score;
    }

    @Override
    public void keyPressed(KeyEvent arg0) {
        // TODO Auto-generated method stub
        int key = arg0.getKeyCode();

        if(key == Left)
        {
            x-=myMovement.getDistanceLeft();
            if(checkWalls())
            {
                x+=10;
            }
        }
        else if(key == Right)
        {
            x+=myMovement.getDistanceRight();
            if(checkWalls())
            {
                x-=10;
            }
        }


        myPanel.repaint();

    }

    public boolean checkWalls()
    {
        ArrayList<Wall> walls = myPanel.getWalls();

        for(int i = 0 ; i < walls.size(); i++)
        {
            if(areRectsColliding(x,x+HEIGHT,y,y+WIDTH,walls.get(i).getX(), walls.get(i).getX()+ walls.get(i).getHEIGHT(),
                    walls.get(i).getY(),walls.get(i).getY()+walls.get(i).getWIDTH()))
                    {
                        return true;
                    }
        }
        return false;

    }

    @Override
    public void keyReleased(KeyEvent arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void keyTyped(KeyEvent arg0) {
        // TODO Auto-generated method stub

    }

    private boolean areRectsColliding(int r1TopLeftX, int r1BottomRightX,
            int r1TopLeftY, int r1BottomRightY, int r2TopLeftX,
            int r2BottomRightX, int r2TopLeftY, int r2BottomRightY) {

        if (r1TopLeftX < r2BottomRightX && r1BottomRightX > r2TopLeftX
                && r1TopLeftY < r2BottomRightY && r1BottomRightY > r2TopLeftY) {
            return true;
        } else {
            return false;
        }
    }

    @Override
    public ImageIcon getImageIcon() {
        // TODO Auto-generated method stub
        return new ImageIcon(imagePath);
    }
}

Answer 1

checkOffScreen 看起来像是在玩家的初始化中，而不是在游戏的主循环中。重画时需要检查x轴，就像移动汽车图像时一样，每次调用移动汽车图像时，都需要检查移动后的x轴。 伪代码

Player.checkOffScreen();
myPanel.repaint();

这应该让汽车在达到给定的参数后回到起点。