鼠标悬停

时间:2017-06-13 21:06:35

标签: java swing jbutton

所以情况是我正在制作一个装有8 * 8按钮的面板,就像一个矩阵,我将不得不根据点击按钮的位置更改特定的按钮文本。制作我自己的JButton似乎是一个好主意,我可以将x和y索引分配给按钮,这样我就可以轻松地检查按钮是否被索引点击了。 这是代码:

import javax.swing.JButton;

public class MatrixButton extends JButton {
    private int x;
    private int y;

    public MatrixButton(int x, int y, String text){
        super(text);
        this.x = x;
        this.y = y;
    }

    public int getX() {
        return x;
    }
    public int getY() {
        return y;
    }
}

它确实解决了这个任务,但是这些Matrix按钮不希望出现,直到我将鼠标悬停在它们上面。可能是什么问题?

这里是面板的代码,它包含这些按钮并处理它们的动作:

public class PlayField extends JPanel implements ActionListener {
    private MatrixButton[][] button = new MatrixButton[8][8];

    public PlayField(){
        Random rand = new Random();

        setLayout(new GridLayout(8, 8));

        for (int i = 0; i < 8; ++i){
            for (int j = 0; j < 8; ++j){
                button[i][j] = new MatrixButton(j, i, "" + rand.nextInt(80));
                button[i][j].addActionListener(this);

                add(button[i][j]);
            }
        }
    }

    private String incrementText(MatrixButton mb){
        return "" + (Integer.parseInt(mb.getText()) + 1);
    }

    @Override
    public void actionPerformed(ActionEvent e){
        MatrixButton mb = (MatrixButton)e.getSource();

        for (int i = mb.getY(); i >= 0; --i){
            button[i][mb.getX()].setText(incrementText(button[i][mb.getX()]));
        }
        for (int i = 0; i < 8; ++i){
            if (i != mb.getX())
            button[mb.getY()][i].setText(incrementText(button[mb.getY()][i]));
        }
    }
}

PS:如果我填写普通的JButton,它们就会出现。这就是为什么我很困惑,因为我在JButton扩展上没有太大改变,只是增加了2个变量。

1 个答案:

答案 0 :(得分:4)

这是危险的代码:

public int getX() {
    return x;
}
public int getY() {
    return y;
}

你确实意识到这会覆盖两个JButton的关键方法(实际上,这些方法来自JButton的父级,JComponent),它们有助于在GUI上设置按钮的位置(添加{{1在方法之上看到这是如此)。我强烈建议您更改这些方法的签名,可能@OverridegetGridX(),甚至更好,使用组合而不是继承,因为您遇到这些类型问题的风险 - 无意中覆盖一种关键方法 - 当你扩展复杂的类时,例如Swing组件类。出于这个原因,我尽量避免扩展这些类,除非绝对必要。

例如:

getGridY()

import java.awt.GridLayout;
import java.awt.event.*;
import java.util.Random;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class PlayField {
    private static final int ROWS = 8;
    private static final int COLS = ROWS;
    private static final int MAX_RAND = 80;
    private JPanel mainPanel = new JPanel();
    private MatrixButton[][] button = new MatrixButton[ROWS][COLS];

    public PlayField(){
        Random rand = new Random();
        mainPanel.setLayout(new GridLayout(ROWS, COLS));
        for (int i = 0; i < ROWS; ++i){
            for (int j = 0; j < COLS; ++j){
                button[i][j] = new MatrixButton(j, i, rand.nextInt(MAX_RAND));
                button[i][j].addActionListener(new MyMatrixListener(i, j));
                mainPanel.add(button[i][j].getButton());
            }
        }
    }

    private class MyMatrixListener implements ActionListener {
        private int i;
        private int j;

        public MyMatrixListener(int i, int j) {
            this.i = i;
            this.j = j;
        }

        @Override
        public void actionPerformed(ActionEvent e) {
            for (int i2 = 0; i2 < button.length; i2++) {
                if (i2 != i) {
                    int value = button[i2][j].getValue();
                    value++;
                    button[i2][j].setValue(value);
                }
            }
            for (int j2 = 0; j2 < button[i].length; j2++) {
                if (j2 != j) {
                    int value = button[i][j2].getValue();
                    value++;
                    button[i][j2].setValue(value);
                }
            }
        }
    }

    public JPanel getMainPanel() {
        return mainPanel;
    }

    private static void createAndShowGui() {
        JFrame
        frame = new JFrame("PlayField");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().add(new PlayField().getMainPanel());
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> createAndShowGui());
    }    
}

最好只使用整数而不是字符串