加载另一个类时,Jpanel不会绘制

时间:2013-10-13 16:14:30

标签: java swing class focus jpanel

我确切知道导致问题的是哪一行,但是没有显示堆栈跟踪错误,所以我留下了调试。让我感到困惑的是,我认为小组没有焦点。首次打开时,面板是空白的,而不是绘制的,但是当我最小化并恢复时,面板会被绘制。我尝试将panel.requestFocus()panel.requestFocusInWindow()添加到绘制屏幕之前正在初始化的类的构造函数中,但它似乎没有做任何事情。这是代码:

JPanel类:

package blackjack;

import java.awt.Color;
import java.awt.Graphics;

import javax.swing.JPanel;

@SuppressWarnings("serial")
public class Board extends JPanel {
    int dealer = 0;
    int player = 0;
    int money = 2500;
    Deck deck;
    Player p = new Player();
    public Board() {
        deck = new Deck(false, this); //if I comment this out, the panel gets painted straight away
    }
    public void paint(Graphics g) {
        super.paintComponent(g);

        g.setColor(Color.GREEN);
        g.fillRect(0,0,getWidth(),getHeight());


        repaint();
    }
}

导致问题的类:

package blackjack;

import java.awt.Image;
import java.util.Random;

import javax.swing.ImageIcon;

public class Deck {
    Card[] deck = new Card[52];
    int[] used = new int[52];
    Random r = new Random();
    public Deck(boolean shuffle, Board b) {
        int i = 0;
        for(int x=0; x<51; x++) {
            used[x] = -1;
        }
        for(Cards card : Cards.values()) {
            if(card.getId() != 53) {
                Image image = new ImageIcon(this.getClass().getResource(card.getImagePath())).getImage();
                deck[i] = new Card(card.getId(),card.getValue(),image);
                i = i+1;
            }
        }
        if(shuffle) shuffle();
        b.requestFocus();
        b.requestFocusInWindow();
    }
    public void shuffle() {
        Card[] shuffled = new Card[52];
        for(int x=0; x<51; x++) {
            int i = pickNotUsed();
            if(i==-1) break;
            shuffled[x] = deck[i];
        }
        deck = shuffled;
    }
    private int pickNotUsed() {
        int notpicked = r.nextInt(52);
        for(int x=0; x<51; x++) {
            if(used[x] != notpicked) {
                return notpicked;
            }
        }
        return -1;
    }
    public Card[] getCards() {
        return deck;
    }
    public Card drawCard() {
        for(int x=0; x<deck.length; x++) {
            if(deck[x] != null) {
                return deck[x];
            }
        }
        return null;
    }
}

原始类,扩展JFrame     包装二十一点;

import javax.swing.JFrame;

@SuppressWarnings("serial")
public class Blackjack extends JFrame {
    public static void main(String[] args) {
        new Blackjack();
    }
    public Blackjack() {
        setSize(1000,600);
        setTitle("Blackjack");
        setResizable(false);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);

        add(new Board());
    }
}

1 个答案:

答案 0 :(得分:0)

  • 在显示之前将组件添加到JFrame(Board)。
  • 不要覆盖 paint 方法,而是将绘图逻辑放到 paintComponent
  

只想专门化UI(外观)委托的paint方法的子类应该覆盖paintComponent。

  • 无需在 paint 方法中调用 repaint(),因为它会导致无限循环。系统会在需要重新绘制时自动调用 Paint 方法,或者当您确实需要重新绘制它时,系统会自动调用它。
  • 不要 requestFocus 直到您真正理解这种行为。在这种情况下,没有必要调用它。

无论如何,即使在这种状态下,你的应用程序也会从一开始就向我展示绿色背景框架。