java - 如何获取 GridLayout 中元素的 X 和 Y 索引？

Question

我正在研究 java 教程，发现在 GridLayout 中查找 JButton 的 x/y 索引的方法是遍历与布局相关联的按钮 b 的二维数组，并检查是否

b[i][j] == buttonReference。

  @Override
  public void actionPerformed(ActionEvent ae) {
    JButton bx = (JButton) ae.getSource();
    for (int i = 0; i < 5; i++)
      for (int j = 0; j < 5; j++)
        if (b[i][j] == bx)
        {
          bx.setBackground(Color.RED);
        }
  }

有没有更简单的方法来获取按钮的 X/Y 索引？

类似于:

JButton button = (JButton) ev.getSource();
int x = this.getContentPane().getComponentXIndex(button);
int y = this.getContentPane().getComponentYIndex(button);

this 是一个 GameWindow 实例，ev ActionEvent 在用户按下按钮时触发。

在这种情况下它应该得到:x == 2, y == 1

@GameWindow.java:

package javaswingapplication;

import java.awt.Color;
import java.awt.GridLayout;
import java.awt.event.*;
import javax.swing.*;

public class GameWindow extends JFrame implements ActionListener
{
  JButton b[][] = new JButton[5][5];

  int v1[] = { 2, 5, 3, 7, 10 };
  int v2[] = { 3, 5, 6, 9, 12 };

  public GameWindow(String title)
  {
    super(title);

    setLayout(new GridLayout(5, 5));
    setDefaultCloseOperation(EXIT_ON_CLOSE );

    for (int i = 0; i < 5; i++)
      for (int j = 0; j < 5; j++)
      {
        b[i][j] = new JButton();
        b[i][j].addActionListener(this);
        add(b[i][j]);
      }
  }

  @Override
  public void actionPerformed(ActionEvent ae) {
    ((JButton)ae.getSource()).setBackground(Color.red);
  }
}

@JavaSwingApplication.java:

package javaswingapplication;

public class JavaSwingApplication {
  public static void main(String[] args) {
    GameWindow g = new GameWindow("Game");
    g.setVisible(true);
    g.setSize(500, 500);
  }
}

Answer 1

这个例子展示了如何创建一个知道它在网格上的位置的网格按钮。 getGridButton() 方法展示了如何根据其网格坐标高效地获取按钮引用， Action 监听器显示点击和找到的按钮是相同的。

package gui;

import java.awt.EventQueue;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

/**
 * @see http://stackoverflow.com/questions/7702697
 */
public class GridButtonPanel {

    private static final int N = 5;
    private final List<JButton> list = new ArrayList<JButton>();

    private JButton getGridButton(int r, int c) {
        int index = r * N + c;
        return list.get(index);
    }

    private JButton createGridButton(final int row, final int col) {
        final JButton b = new JButton("r" + row + ",c" + col);
        b.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                JButton gb = GridButtonPanel.this.getGridButton(row, col);
                System.out.println("r" + row + ",c" + col
                    + " " + (b == gb)
                    + " " + (b.equals(gb)));
            }
        });
        return b;
    }

    private JPanel createGridPanel() {
        JPanel p = new JPanel(new GridLayout(N, N));
        for (int i = 0; i < N * N; i++) {
            int row = i / N;
            int col = i % N;
            JButton gb = createGridButton(row, col);
            list.add(gb);
            p.add(gb);
        }
        return p;
    }

    private void display() {
        JFrame f = new JFrame("GridButton");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(createGridPanel());
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

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

            @Override
            public void run() {
                new GridButtonPanel().display();
            }
        });
    }
}