java - Java 中的 JPanel 发生了什么？我究竟做错了什么？

Question

我的 JPanel 有问题。我告诉它最后重绘() 构造函数然后我有动画(一个 Sprite 在 屏幕)，但 JPanel 在 Sprite 消失之前不会自行绘制 通过它的动画并到达屏幕上的新点。我贴的 我的代码如下。我以前从未将 JPanel 用于自定义图形。 我究竟做错了什么？

import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.util.*;
import javax.swing.*;

class Battle extends JPanel implements KeyListener {

    AllyParty ap;
    boolean showMenu = false;
    BufferedImage image;
    EnemyParty ep;
    Graphics screen;
    Image allyPic[], enemyPic[];
    int enemyCount;
    int mtCount = 0;
    int turn[];
    MediaTracker mt;
    Random rand;

    public Battle(AllyParty allyparty) {

        /*Initial JPanel subclass setup*/
        setSize(800, 600);
        setBackground(Color.black);

        /*Create our ally party*/
        ap = new AllyParty();
        ap = allyparty;
        ap.setCallingObject(this);

        /*Create randomizer and random number variable*/
        long seed = System.currentTimeMillis();
        rand = new Random(seed);

        /*Use rand to select a number of enemies*/
        enemyCount = rand.nextInt(12) + 1;

        enemyCount = 12; //TEMP 
        ep = new EnemyParty(enemyCount);


        /*Create the individual enemies in ep and place them*/
        for (int i = 0; i < enemyCount; i++) {
            ep.enemy[i] = new Enemy(1);
        }

        ep.setCallingObject(this);

        /*Initialize images and set them to their starting values*/
        allyPic = new Image[4];
        enemyPic = new Image[enemyCount];

        /* for (int i = 0; i < 4; i++) 
        { 
        ap.ally[i].setCurrentImage(Ally.STAND) 
        allyPic[i] = ap.ally[i].getCurrentImage(); 
        } 

        for (int i = 0; i < enemyCount; i++) 
        { 
        enemyPic[i] = ep.enemy[i].getImage(); 
         */
        /*Set battle placement*/
        ap.setPos(0);
        ep.setPos(0);

        //Create the Buffered Image 
        image = new BufferedImage(800, 600, BufferedImage.TYPE_INT_RGB);

        //Set up the Media Tracker 
        mt = new MediaTracker(this);
        for (int i = 0; i < 4; i++) {
            mt.addImage(allyPic[i], mtCount++);
        }

        for (int i = 0; i < ep.getEnemyCount(); i++) {
            mt.addImage(enemyPic[i], mtCount++);
        }

        mt.addImage(image, mtCount++);

        try {
            mt.waitForAll();
        } catch (Exception e) {
        }

        /*Temporary Section*/
        findTurns();

        repaint();
        // ap.ally[0].advance(); 
        advance();
    }

    public void findTurns() {
        int total = ep.getEnemyCount() + 4; //Enemies + allies 

        int used[] = new int[total];
        turn = new int[total];

        int next = rand.nextInt(total);

        for (int j = 0; j < total; j++) {
            used[j] = -1;
        }

        for (int j = 0; j < total; j++) {
            for (int k = 0; k < j; k++) {
                if (used[k] == next) {
                    k = -1;
                    next = rand.nextInt(total);
                }
            }
            turn[j] = next;
            used[j] = next;
        }
    }

    public void advance() {
        while (ap.ally[0].getXPos() > 350) {
            ap.ally[0].moveLeft(20);
            ap.ally[0].setCurrentImage(Ally.WALK);
            repaint();
            try {
                Thread.sleep(200);
            } catch (Exception e) {
            }
            ap.ally[0].setCurrentImage(Ally.STAND);
            repaint();
            try {
                Thread.sleep(200);
            } catch (Exception e) {
            }
        }
    }

    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        screen = image.getGraphics();

        for (int i = 0; i < 4; i++) {
            allyPic[i] = ap.ally[i].getCurrentImage();
        }

        for (int i = 0; i < ep.getEnemyCount(); i++) {
            enemyPic[i] = ep.enemy[i].getCurrentImage();
        }

        for (int i = 0; i < 4; i++) {
            screen.drawImage(allyPic[i], ap.ally[i].getXPos(),
                ap.ally[i].getYPos(), this);
        }

        for (int i = 0; i < enemyCount; i++) {
            screen.drawImage(enemyPic[i], ep.enemy[i].getXPos(),
                ep.enemy[i].getYPos(), 100, 75, this);
        }

        g.drawImage(image, 0, 0, this);
    }

    public void keyPressed(KeyEvent k) {}
    public void keyReleased(KeyEvent k) {}
    public void keyTyped(KeyEvent k) {}
}

Answer 1

What am I doing wrong? 

1) 使用 KeyBindings而不是 KeyListener

2) 不要在 EDT 期间使用 Thread.sleep(int)，因为会导致 freeze Swing GUI

3) 用于动画/延迟事件使用 Swing Timer

4) 你可以使用Icon在JLabel用于在 JPanel 中显示 BufferedImage