Question

在java中我尝试使用容器类中的getComponentAt（x，y）方法。但对于给定的（x，y）坐标，它总是返回类javax.swing.JRootPane的对象，即使（x，y）包含一些图像/ JLabel / JButton。

import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.JButton;
import javax.swing.JFrame;

public class temp2 implements MouseListener{
    public static void main(String[] arg){
        frame = new JFrame("adsa");
        frame.setBounds(0, 0, 1000, 1000);
        frame.setVisible(true);
        frame.addMouseListener(new temp2());
        JButton l = new JButton("asdasd");
        frame.add(l);
        l.addMouseListener(new temp2());;
    }
    static JFrame frame;
    @Override
    public void mouseClicked(MouseEvent e) {
        int x = e.getX();
        int y = e.getY();
            System.out.println(frame.getComponentAt(x, y).getClass());
        System.out.println(frame.getComponentAt(x, y) instanceof JButton);

    }
    @Override
    public void mousePressed(MouseEvent e) {
        // TODO Auto-generated method stub

    }
    @Override
    public void mouseReleased(MouseEvent e) {
        // TODO Auto-generated method stub

    }
    @Override
    public void mouseEntered(MouseEvent e) {
        // TODO Auto-generated method stub

    }
    @Override
    public void mouseExited(MouseEvent e) {
        // TODO Auto-generated method stub

    }

}

这是我用于测试的示例代码.. 每当我点击按钮时，我都会得到以下输出：

class javax.swing.JRootPane 
false

Answer 1

你必须寻找SwingUtilities#getDeepestComponentAt，例如

import java.awt.Component;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.*;

public class TestMouseListener {

    public static void main(String[] args) {
        final JComboBox combo = new JComboBox();
        combo.setEditable(true);
        for (int i = 0; i < 10; i++) {
            combo.addItem(i);
        }
        final JLabel tip = new JLabel();
        tip.setText("Outside combobox");
        JPanel panel = new JPanel();
        panel.add(combo);
        panel.add(tip);
        panel.addMouseListener(new MouseAdapter() {

            @Override
            public void mouseEntered(MouseEvent e) {
                tip.setText("Outside combobox");
            }

            @Override
            public void mouseExited(MouseEvent e) {
                Component c = SwingUtilities.getDeepestComponentAt(
                        e.getComponent(), e.getX(), e.getY());
                tip.setText(c != null && SwingUtilities.isDescendingFrom(
                        c, combo) ? "Inside combo box" : "Outside combobox");
            }
        });
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        frame.add(panel);
        frame.pack();
        frame.setVisible(true);

    }

    private TestMouseListener() {
    }
}

Answer 2

这取决于您构建UI的方式，但请尝试Container#findCompoinentAt(int x, int y) - 它会返回最顶层的可见子项。

Answer 3

问题来自于您将侦听器添加到多个组件这一事实，但您总是引用该帧来检索组件。你应该做的是：

Component c = ((Component)e.getSource()).getComponentAt(e.getX(), e.getY());
// Do some stuff about c.

事件坐标是相对于触发事件的组件。

什么是来自acm java Libraries（Graphics Program）的getElementAt（double x，double y）的java等价物;

3 个答案: