無法使用GridBagLayout替換其他JLabel JLabel

Question

我有一個程序通過GridBagLayout佈局管理器顯示4x4方格網格。將顯示全部包含square.gif的16個JLabels。點擊其中一個矩形時，應該用包含圖像的JLabel（例如帽子）替換它。所以，圖像取代了被點擊的矩形。

但是，此刻發生的情況是，僅點擊的矩形有時會被替換。其他時候，矩形會消失，但圖像不會取代它。其他時候，圖像將顯示在之前點擊過的矩形中，但只有在單擊不同的矩形後纔會顯示。我在下面放置了最相關的代碼。

public void displayGrid() { 


    c.gridx = 0; 
    c.gridy = 0; 

    try { 
     squareImage = ImageIO.read(this.getClass().getResource("stimulus(0).gif")); //line 37 

    } catch (IOException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } 

    JLabel squareLabel = new JLabel(new ImageIcon(squareImage)); 

    for(int i = 0; i < 16; i++){ 
     c.gridx = i % 4; 
     c.gridy = i/4; 
     squareLabel = new JLabel(new ImageIcon(squareImage)); 
     squareLabels[i] = squareLabel; 
     panel.add(squareLabels[i], c); 
     squareLabels[i].addMouseListener(this); 

     System.out.println(c.gridx + "" + c.gridy); 

    } 

    panel.validate(); 

} 

public void mousePressed(MouseEvent e) { 

    for(int i = 0; i < squareLabels.length; i++){ 
     if(e.getSource() == squareLabels[i]){ 
      //JLabel removedLabel = squareLabels[i]; 
      c.gridx = (i/4); 
      c.gridy = (i%4); 
      panel.remove(squareLabels[i]); 
      panel.revalidate(); 
      panel.repaint(); 
      panel.add(stimuliLabels[0], c); 
      panel.validate(); 

     } 
    } 

} 

在的mousePressed（）方法，我試圖編寫的代碼，確定被按下的一個JLabel時，獲取的JLabel的的GridBagConstraints，刪除該被點擊選擇JLabel，然後替換的JLabel與具有給定GridBagConstraints的新JLabel。但是，正如我已經說過的那樣，該計劃沒有按計劃進行，我不知道爲什麼。

感謝您花時間閱讀本文。任何幫助，將不勝感激。

Answer 1

爲什麼要換JLabels？ JLabels是爲了保存圖標（通常是ImageIcons）而構建的，如果要交換圖像，最好將JLabels留在原位，並簡單地交換顯示的ImageIcon，通過調用setIcon(...)即可輕鬆完成。這比你想要做的要容易得多，這與圖書館一起工作，而不是像你正在做的那樣對付它。

public void mousePressed(MouseEvent e) { 
    // assuming that only JLabels are given this MouseListener: 
    JLabel label = (JLabel) e.getSource(); 
    label.setIcon(desiredNewIcon); 
} 

例如，從我回答一個similar question：

import java.awt.GridLayout; 
import java.awt.event.MouseAdapter; 
import java.awt.event.MouseEvent; 
import java.awt.image.BufferedImage; 
import java.io.IOException; 
import java.net.URL; 
import java.util.ArrayList; 
import java.util.List; 
import java.util.Random; 
import javax.imageio.ImageIO; 
import javax.swing.*; 

@SuppressWarnings("serial") 
public class RandomChessMen extends JPanel { 
    // for this example I get a sprite sheet that holds several sprite images in it 
    // the images can be found here: https://stackoverflow.com/questions/19209650 
    private static final String IMAGE_PATH = "http://i.stack.imgur.com/memI0.png"; 
    private static final int LABEL_COUNT = 2; 
    private static final int ICON_COLUMNS = 6; 
    private Random random = new Random(); 

    public RandomChessMen() throws IOException { 
     URL url = new URL(IMAGE_PATH); 
     BufferedImage largeImg = ImageIO.read(url); 
     setLayout(new GridLayout(1, 0)); 

     // break down large image into its constituent sprites and place into ArrayList<Icon> 
     int w = largeImg.getWidth()/ICON_COLUMNS; 
     int h = largeImg.getHeight()/LABEL_COUNT; 
     for (int i = 0; i < LABEL_COUNT; i++) { 
     final List<Icon> iconList = new ArrayList<>(); 
     int y = (i * largeImg.getHeight())/LABEL_COUNT; 
     // get 6 icons out of large image 
     for (int j = 0; j < ICON_COLUMNS; j++) { 
      int x = (j * largeImg.getWidth())/ICON_COLUMNS; 
      // get subImage 
      BufferedImage subImg = largeImg.getSubimage(x, y, w, h); 
      // create ImageIcon and add to list 
      iconList.add(new ImageIcon(subImg)); 
     } 

     // create JLabel 
     final JLabel label = new JLabel("", SwingConstants.CENTER); 
     int eb = 40; 
     label.setBorder(BorderFactory.createEmptyBorder(eb, eb, eb, eb)); 

     // get random index for iconList 
     int randomIndex = random.nextInt(iconList.size()); 
     Icon icon = iconList.get(randomIndex); // use index to get random Icon 
     label.setIcon(icon); // set label's icon 
     label.addMouseListener(new MouseAdapter() { 
      @Override 
      public void mousePressed(MouseEvent e) { 
       Icon secondIcon = label.getIcon(); 
       // so we don't repeat icons 
       while (label.getIcon() == secondIcon) { 
        int randomIndex = random.nextInt(iconList.size()); 
        secondIcon = iconList.get(randomIndex); 
       } 
       label.setIcon(secondIcon); 
      } 
     }); 
     // add to GUI 
     add(label); 
     } 
    } 

    private static void createAndShowGui() { 
     JFrame frame = new JFrame("RandomImages"); 
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     try { 
     frame.getContentPane().add(new RandomChessMen()); 
     } catch (IOException e) { 
     e.printStackTrace(); 
     System.exit(-1); 
     } 
     frame.pack(); 
     frame.setLocationRelativeTo(null); 
     frame.setVisible(true); 
    } 

    public static void main(String[] args) { 
     SwingUtilities.invokeLater(new Runnable() { 
     public void run() { 
      createAndShowGui(); 
     } 
     }); 
    } 
}