Java 7 bug Container.remove() 删除所有组件

Question

我有一个带有一个直接子级的 AWT 容器，并在索引 0 处添加一个新子级，使其可见，验证父级框架并重新绘制。 (子级是扩展 Panel 的类，但这似乎不相关。)一切都很好，并且 Container 按预期包含 2 个直接子级。

然后，我通过隐藏 child 并调用 Container.remove(this) 来解雇该 child 。从 child 那里获取，然后验证并重新绘制容器。在 1.7 之前的所有 JRE 上，这都可以正常工作，并且原始子项保留在容器中。然而在 1.7 上 remove(this)还删除原来的子项，即清空容器。调用Container.remove(0)具有相同的效果。有人知道如何解决这个问题吗？它看起来像是一个可怕的 JVM 错误。

即- 开始时:容器包含子项 [A]。- 添加 B 后，Container 包含子项 [B,A]。- 调用remove(this)或remove(0)后，Container不包含任何内容:[]。

虽然我可以检索 remove() 之前的原始子项，然后add()它重新回来，这不可避免地会导致重大的重新绘制和 Not Acceptable 性能。

Answer 1

我认为不正确，我无法模拟这个问题，

我这边是Win7、JDK7_04

打印输出

run:
 Components Count after Adds :2
 Components Count after Adds :3
 Components Count after Adds :4
 Components Count after Adds :5
 Components Count after Adds :6
 Components Count after Adds :7
 Components Count after Removes :6
 Components Count after Removes :5
 Components Count after Removes :4
 Components Count after Removes :3
 Components Count after Removes :2
 Components Count after Removes :1
BUILD SUCCESSFUL (total time: 2 minutes 14 seconds)

来自代码

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JCheckBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.LineBorder;

public class AddComponentsAtRuntime {

    private JFrame f;
    private Container panel;
    private JCheckBox checkValidate, checkReValidate, checkRepaint, checkPack;

    public AddComponentsAtRuntime() {
        JButton b = new JButton();
        b.setBackground(Color.red);
        b.setBorder(new LineBorder(Color.black, 2));
        b.setPreferredSize(new Dimension(600, 10));
        panel = new Container();
        panel.setLayout(new GridLayout(0, 1));
        panel.add(b);
        f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(panel, "Center");
        f.add(getCheckBoxPanel(), "South");
        f.setLocation(200, 200);
        f.pack();
        f.setVisible(true);
    }

    private JPanel getCheckBoxPanel() {
        checkValidate = new JCheckBox("validate");
        checkValidate.setSelected(false);
        checkReValidate = new JCheckBox("revalidate");
        checkReValidate.setSelected(false);
        checkRepaint = new JCheckBox("repaint");
        checkRepaint.setSelected(false);
        checkPack = new JCheckBox("pack");
        checkPack.setSelected(false);
        JButton addComp = new JButton("Add New One");
        addComp.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                JButton b = new JButton();
                b.setBackground(Color.red);
                b.setBorder(new LineBorder(Color.black, 2));
                b.setPreferredSize(new Dimension(600, 10));
                panel.add(b);
                makeChange();
                System.out.println(" Components Count after Adds :" + panel.getComponentCount());
            }
        });
        JButton removeComp = new JButton("Remove One");
        removeComp.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                int count = panel.getComponentCount();
                if (count > 0) {
                    panel.remove(0);
                }
                makeChange();
                System.out.println(" Components Count after Removes :" + panel.getComponentCount());
            }
        });
        JPanel panel2 = new JPanel();
        panel2.add(checkValidate);
        panel2.add(checkReValidate);
        panel2.add(checkRepaint);
        panel2.add(checkPack);
        panel2.add(addComp);
        panel2.add(removeComp);
        return panel2;
    }

    private void makeChange() {
        if (checkValidate.isSelected()) {
            panel.validate();
        }
        if (checkReValidate.isSelected()) {
            panel.revalidate();
        }
        if (checkRepaint.isSelected()) {
            panel.repaint();
        }
        if (checkPack.isSelected()) {
            f.pack();
        }
    }

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

            @Override
            public void run() {
                AddComponentsAtRuntime makingChanges = new AddComponentsAtRuntime();
            }
        });
    }
}