java - keyReleased 上出现 StackOverflowError，但 mouseReleased 工作正常

Question

用鼠标选择效果很好，如下面的运行时日志所示:

init:
Deleting: /home/thufir/NetBeansProjects/gnumail-providers/build/built-jar.properties
deps-jar:
Updating property file: /home/thufir/NetBeansProjects/gnumail-providers/build/built-jar.properties
compile:
run:
Mar 30, 2013 10:16:36 PM net.bounceme.dur.nntp.swing.ArticlesPanel itemSelected
INFO: selected      item        8
Mar 30, 2013 10:16:39 PM net.bounceme.dur.nntp.swing.ArticlesPanel itemSelected
INFO: selected      item        1
Mar 30, 2013 10:16:41 PM net.bounceme.dur.nntp.swing.ArticlesPanel itemSelected
INFO: selected      item        5
Mar 30, 2013 10:16:42 PM net.bounceme.dur.nntp.swing.ArticlesPanel itemSelected
INFO: selected      item        3
Mar 30, 2013 10:16:44 PM net.bounceme.dur.nntp.swing.ArticlesPanel itemSelected
INFO: selected      item        7
Exception in thread "AWT-EventQueue-0" java.lang.StackOverflowError
    at net.bounceme.dur.nntp.swing.ArticlesPanel$2.keyReleased(ArticlesPanel.java:49)
    at net.bounceme.dur.nntp.swing.ArticlesPanel$2.keyReleased(ArticlesPanel.java:49)
    at net.bounceme.dur.nntp.swing.ArticlesPanel$2.keyReleased(ArticlesPanel.java:49)
    at net.bounceme.dur.nntp.swing.ArticlesPanel$2.keyReleased(ArticlesPanel.java:49)
    at net.bounceme.dur.nntp.swing.ArticlesPanel$2.keyReleased(ArticlesPanel.java:49)

但是当按键和鼠标选择确实(或应该)调用相同的方法:itemSelected时，为什么使用键盘箭头进行选择会导致StackOverflowError。

相关类:

package net.bounceme.dur.nntp.swing;

import gnu.mail.providers.nntp.GroupMetaData;
import java.util.List;
import java.util.logging.Logger;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.swing.DefaultListModel;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import net.bounceme.dur.nntp.gnu.PMD;
import net.bounceme.dur.nntp.gnu.Page;
import net.bounceme.dur.nntp.gnu.Usenet;

public class ArticlesPanel extends JPanel {

    private static final Logger LOG = Logger.getLogger(ArticlesPanel.class.getName());
    private static final long serialVersionUID = 1L;
    private JList<String> jList = new JList<>();
    private JScrollPane scrollPane = new JScrollPane();
    private DefaultListModel<String> dlm;

    public ArticlesPanel() throws MessagingException {

        initComponents();
    }

    @SuppressWarnings("unchecked")
    private void initComponents() {
        setLayout(new java.awt.BorderLayout());

        dlm = new DefaultListModel<>();
        for (int i = 1; i < 9; i++) {
            dlm.addElement("item\t\t" + i);
        }

        jList.setModel(dlm);
        jList.setSelectionMode(javax.swing.ListSelectionModel.SINGLE_SELECTION);
        jList.addMouseListener(new java.awt.event.MouseAdapter() {

            public void mouseReleased(java.awt.event.MouseEvent evt) {
                mouseReleases(evt);
            }
        });
        jList.addKeyListener(new java.awt.event.KeyAdapter() {

            public void keyReleased(java.awt.event.KeyEvent evt) {
                keyReleased(evt);
            }
        });

        scrollPane.setViewportView(jList);
        add(scrollPane, java.awt.BorderLayout.CENTER);

        this.setSize(300, 100);
        this.setVisible(true);
    }

    private void keyReleased(java.awt.event.KeyEvent evt) {
        itemSelected();
    }

    private void mouseReleases(java.awt.event.MouseEvent evt) {
        itemSelected();
    }

    private void itemSelected() {
        LOG.info("selected\t\t" + jList.getSelectedValue());
    }
}

和调用类:

package net.bounceme.dur.nntp.swing;

import java.util.logging.Logger;
import javax.mail.MessagingException;
import javax.swing.*;
import java.awt.*;

public class Driver {

    private static final Logger LOG = Logger.getLogger(Driver.class.getName());

    private static void createAndShowGUI() throws MessagingException  {
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setResizable(true);
        GraphicsEnvironment e = GraphicsEnvironment.getLocalGraphicsEnvironment();
        frame.setMaximizedBounds(e.getMaximumWindowBounds());
        frame.setExtendedState(frame.getExtendedState() | JFrame.MAXIMIZED_BOTH);
        frame.setLayout(new BorderLayout());

        JTabbedPane tabs = new JTabbedPane();

        ArticlesPanel myPanel = new ArticlesPanel();
        tabs.add(myPanel);
        frame.add(tabs);

        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String... args) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {

            public void run() {
                try {
                    createAndShowGUI();
                } catch (MessagingException ex) {
                    LOG.warning(ex.getLocalizedMessage());
                }
            }
        });
    }
}

Answer 1

您在 keyReleased(evt) 调用中收到 StackOverflowError，因为 KeyAdapter 中的方法隐藏了 中的方法文章面板。结果是无限递归:

public void keyReleased(java.awt.event.KeyEvent evt) {
    keyReleased(evt); // calling this same method again
}

这不会在您的 mouseReleased 调用中发生，因为您自己的方法称为 mouseReleases(请注意 s)。

public void mouseReleased(java.awt.event.MouseEvent evt) {
    mouseReleases(evt); // calling the method in the outer class
}