JLabel图像阵列

Question

我试图将相同的jlabel存储图像两次加载到gridlayout面板中,但是不是创建图像的两个实例,而是仅显示一次然后移动图像.

如何将件数组中的相同JLabel位置存储到boardLabels数组中的多个JLabel中.

谢谢 :)

public static JPanel boardPanel = new JPanel(new GridLayout(4, 0));
public static JLabel pieces[] = new JLabel[2];
private static JLabel[] boardLabels = new JLabel[4];

public MainFrame() {
    pieces[0] = new JLabel(new ImageIcon(System.getProperty("user.dir") + "/images/piece1.png"));
    pieces[1] = new JLabel(new ImageIcon(System.getProperty("user.dir") + "/images/piece2.png"));

    this.add(boardPanel);
    displayGUIboard();
}


public static void displayGUIboard() {

    //ERROR - the label in pieces[0] is not copied into both boardLabels [0] and [1]
    boardLabels[0] = pieces[0];
    boardLabels[1] = pieces[0];

    boardPanel.add(boardLabels[0]);
    boardPanel.add(boardLabels[1]);
}

public static void main(String[] args) {
    MainFrame frame = new MainFrame();
    frame.setVisible(true);
    frame.setSize(600, 600);
    frame.setLocationRelativeTo(null);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}

这有效

    boardLabels[0] = new JLabel(pieces[1]);
    boardLabels[1] = new JLabel(pieces[1]);

当使用ImageIcons时,我想避免这种情况,因为要更新电路板,我必须删除然后重新加载JLabel.我更愿意只更新已加载的标签.

编辑 我之前尝试过这个但它抛出一个空指针异常...

    boardLabels[0].setIcon(pieces[1]);
    boardLabels[1].setIcon(pieces[1]);

    boardPanel.add(boardLabels[0]);
    boardPanel.add(boardLabels[1]);

Answer 1

为了比较,我重新考虑了@ HFOE的示例,以便Ground implements Icon为返回的数组编制索引values().作为value一个实现细节,int[][] MAP可以改为Ground[][] MAP.

更新:此变体说明Ground[][] MAP并添加TexturePaint.

import java.awt.Color;
import java.awt.Component;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridLayout;
import java.awt.TexturePaint;
import java.awt.geom.Rectangle2D;
import java.awt.image.BufferedImage;
import java.util.Random;
import javax.swing.*;

/** @see https://stackoverflow.com/a/11556441/230513 */
public class GridExample extends JPanel {

    public static final Ground[][] MAP = {
        {Ground.GRASS, Ground.GRASS, Ground.DIRT, Ground.WATER, Ground.WATER},
        {Ground.GRASS, Ground.DIRT, Ground.CITY, Ground.WATER, Ground.WATER},
        {Ground.GRASS, Ground.DIRT, Ground.CITY, Ground.WATER, Ground.WATER},
        {Ground.GRASS, Ground.DIRT, Ground.DIRT, Ground.DIRT, Ground.WATER},
        {Ground.GRASS, Ground.GRASS, Ground.DIRT, Ground.WATER, Ground.WATER},
    };
    private JLabel[][] labelGrid = new JLabel[MAP.length][MAP[0].length];

    public GridExample() {
        setLayout(new GridLayout(MAP.length, MAP[0].length));
        for (int r = 0; r < labelGrid.length; r++) {
            for (int c = 0; c < labelGrid[r].length; c++) {
                labelGrid[r][c] = new JLabel();
                labelGrid[r][c].setIcon(MAP[r][c]);
                add(labelGrid[r][c]);
            }
        }
    }

    private static void createAndShowGui() {
        GridExample mainPanel = new GridExample();
        JFrame frame = new JFrame("GridExample");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(mainPanel);
        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);
    }

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

            @Override
            public void run() {
                createAndShowGui();
            }
        });
    }
}

enum Ground implements Icon {

    DIRT(new Color(205, 133, 63)), GRASS(new Color(0, 107, 60)),
    WATER(new Color(29, 172, 214)), CITY(Color.lightGray);
    private static final int SIZE = 42;
    private Random random = new Random();
    private TexturePaint paint;

    private Ground(Color color) {
        this.paint = initPaint(color);
    }

    private TexturePaint initPaint(Color color) {
        BufferedImage image = new BufferedImage(
            SIZE, SIZE, BufferedImage.TYPE_INT_ARGB);
        Rectangle2D.Double rect = new Rectangle2D.Double(0, 0, SIZE, SIZE);
        for (int row = 0; row < SIZE; row++) {
            for (int col = 0; col < SIZE; col++) {
                if (random.nextBoolean()) {
                    image.setRGB(col, row, color.getRGB());
                } else {
                    if (random.nextBoolean()) {
                        image.setRGB(col, row, color.darker().getRGB());
                    } else {
                        image.setRGB(col, row, color.brighter().getRGB());
                    }
                }
            }
        }
        return new TexturePaint(image, rect);
    }

    @Override
    public void paintIcon(Component c, Graphics g, int x, int y) {
        Graphics2D g2d = (Graphics2D) g;
        g2d.setPaint(paint);
        g.fillRect(0, 0, SIZE, SIZE);
    }

    @Override
    public int getIconWidth() {
        return SIZE;
    }

    @Override
    public int getIconHeight() {
        return SIZE;
    }
}

Answer 2

不要这样做,因为您不能将多个相同的组件多次添加到可视化容器中.最好使用多个JLabel,但让它们使用相同的ImageIcon.ImageIcons可以轻松使用多次:

public MainFrame() {
    pieceIcon[0] = new ImageIcon(System.getProperty("user.dir") + 
        "/images/piece1.png");
    pieceIcon[1] = new ImageIcon(System.getProperty("user.dir") + 
        "/images/piece2.png");

    this.add(boardPanel);
    displayGUIboard();
}


public void displayGUIboard() {
    boardPanel.add(new JLabel(pieceIcon[0]);
    boardPanel.add(new JLabel(pieceIcon[0]);
}

顺便说一句:请注意,没有你的变量应该是静态的.

编辑:关于您最近的编辑:

这有效

boardLabels[0] = new JLabel(pieces[1]);
boardLabels[1] = new JLabel(pieces[1]);

当使用ImageIcons时,我想避免这种情况,因为要更新电路板,我必须删除然后重新加载JLabel.我更愿意只更新已加载的标签."

解决方案
不,您根本不需要更改JLabel.将JLabel保持原样,只需使用JLabel setIcon(...)方法交换它们所持有的图标即可.

编辑
另外,不要将变量与对象混淆.即使您创建了一堆JLabel变量,如果它们都引用相同的JLabel对象,您仍然无法将多个JLabel对象多次添加到容器中.

编辑 你说:

代码是游戏显示功能的一部分.整数数组将表示被解释的板(但不在上面的代码中),并且正确的Jlabel图像将被放置在gridlayout面板中以显示板的gui.我已经让显示代码工作正常,但在我当前的版本中,它从板上删除jlabel然后创建新的JLabel(片...)...但我更喜欢它从整数数组更新自己而不是删除标签,读取数组,然后重新创建标签.

因此,创建一个使用GridLayout并使用不变的JLabel填充它的JPanel.然后,只需根据int数组保存的值更改JLabels所拥有的图标.您可以创建一个简化和自动化此过程的方法.

编辑:

编辑我之前尝试过,但它抛出一个空指针异常.

然后像解决任何NPE一样解决这个问题.找出抛出NPE的行,检查行上的变量,至少有一行是null,然后修复它以便在尝试使用它之前初始化变量.

编辑
例如:

import java.awt.Color;
import java.awt.Graphics;
import java.awt.GridLayout;
import java.awt.image.BufferedImage;

import javax.swing.*;

@SuppressWarnings("serial")
public class GridExample extends JPanel {
   public static final int[][] MAP = {
      {1, 0, 0, 2, 2, 2, 2, 2, 2, 2, 2},
      {1, 1, 0, 0, 2, 2, 2, 2, 2, 2, 2},
      {1, 1, 1, 0, 2, 2, 2, 2, 2, 2, 2},
      {1, 1, 1, 0, 0, 2, 2, 2, 2, 2, 2},
      {1, 1, 1, 1, 0, 2, 2, 2, 2, 2, 2},
      {1, 1, 1, 0, 0, 0, 2, 2, 2, 2, 2},
      {1, 1, 0, 0, 0, 2, 2, 2, 2, 2, 2},
      {1, 1, 1, 0, 0, 0, 2, 2, 2, 2, 2},
      {1, 1, 1, 1, 1, 0, 0, 0, 0, 2, 2},
      {1, 1, 1, 1, 1, 0, 0, 0, 2, 2, 2},
      {1, 1, 1, 1, 1, 1, 0, 0, 0, 2, 2}
   };

   public static final Color[] COLORS = {};
   private JLabel[][] labelGrid = new JLabel[MAP.length][MAP[0].length];

   public GridExample() {
      setLayout(new GridLayout(MAP.length, MAP[0].length));
      for (int r = 0; r < labelGrid.length; r++) {
         for (int c = 0; c < labelGrid[r].length; c++) {
            labelGrid[r][c] = new JLabel();
            labelGrid[r][c].setIcon(Ground.getGround(MAP[r][c]).getIcon());
            add(labelGrid[r][c]);            
         }
      }
   }

   private static void createAndShowGui() {
      GridExample mainPanel = new GridExample();

      JFrame frame = new JFrame("GridExample");
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.getContentPane().add(mainPanel);
      frame.pack();
      frame.setLocationByPlatform(true);
      frame.setVisible(true);
   }

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

enum Ground {
   DIRT(0, new Color(205,133, 63)), GRASS(1, new Color(0, 107, 60)), 
   WATER(2, new Color(29, 172, 214));
   private int value;
   private Color color;
   private Icon icon;

   private Ground(int value, Color color) {
      this.value = value;
      this.color = color;

      icon = createIcon(color);
   }

   private Icon createIcon(Color color) {
      int width = 24; // how to use const in enum? 
      BufferedImage img = new BufferedImage(width, width, BufferedImage.TYPE_INT_ARGB);
      Graphics g = img.getGraphics();
      g.setColor(color);
      g.fillRect(0, 0, width, width);
      g.dispose();
      return new ImageIcon(img);
   }

   public int getValue() {
      return value;
   }

   public Color getColor() {
      return color;
   }

   public Icon getIcon() {
      return icon;
   }

   public static Ground getGround(int value) {
      for (Ground ground : Ground.values()) {
         if (ground.getValue() == value) {
            return ground;
         }
      }
      return null;
   }

}

其中显示了GUI网格: