java - 摆动组件未居中

Question

我刚刚在我的 GUI 中添加了一个徽标和 beta 消息。但是，它并不完全正确居中：

这是我的代码：

package me.nrubin29.quiz.create;

import me.nrubin29.quiz.MessageUtil;

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.io.File;

public class WelcomeGUI extends JFrame {

    private static final long serialVersionUID = 1L;

    private DefaultListModel contents = new DefaultListModel();
    private JLabel logo, betaText = new JLabel("This is beta software and should not be distributed without consent from its creator.");
    private JList list = new JList(contents);
    private JPanel contentsPanel = new JPanel(), buttonPanel = new JPanel(), logoPanel = new JPanel(), betaPanel = new JPanel();
    private JButton open = new JButton("Open"), delete = new JButton("Delete"), rename = new JButton("Rename"), newQuiz = new JButton("New");

    public WelcomeGUI() {
        super("AutoQuiz");

        try { logo = new JLabel(MessageUtil.ImageType.LOGO_LANDSCAPE.getImageIcon()); }
        catch (Exception e) { e.printStackTrace(); }

        logo.setHorizontalAlignment(SwingConstants.CENTER);

        betaText.setHorizontalAlignment(SwingConstants.CENTER);

        list.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent evt) {
                if (evt.getClickCount() == 2) open.doClick();
            }
        });

        list.addKeyListener(new KeyAdapter() {
            @Override
            public void keyPressed(KeyEvent e) {
                if (e.getKeyCode() == KeyEvent.VK_ENTER) open.doClick();
            }
        });

        for (String file : FileManager.getInstance().getRootFolder().list()) {
            try { if (file.substring(file.lastIndexOf(".")).equals(".quiz")) contents.addElement(file.substring(0, file.lastIndexOf("."))); }
            catch (Exception ignored) { }
        }

        if (contents.size() > 0) list.setSelectedIndex(0);

        open.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                if (list.getSelectedIndex() != -1) {
                    File load = FileManager.getInstance().getFile(contents.get(list.getSelectedIndex()) + ".quiz");
                    new CreatorGUI(load, WelcomeGUI.this);
                }
            }
        });

        delete.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                if (list.getSelectedIndex() != -1) {
                    File choice = FileManager.getInstance().getFile(contents.get(list.getSelectedIndex()) + ".quiz");
                    contents.remove(list.getSelectedIndex());
                    if (!choice.delete()) MessageUtil.msg(WelcomeGUI.this, "Error", "Could not delete file.", MessageUtil.MessageType.ERROR, MessageUtil.ImageType.ICON);
                }
            }
        });

        rename.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                if (list.getSelectedIndex() != -1) {
                    File load = FileManager.getInstance().getFile(contents.get(list.getSelectedIndex()) + ".quiz");
                    String name = JOptionPane.showInputDialog(WelcomeGUI.this, "Please enter a new name.", contents.get(list.getSelectedIndex()));
                    if (name == null) return;
                    if (!load.renameTo(FileManager.getInstance().getFile(name + ".quiz"))) MessageUtil.msg(WelcomeGUI.this, "Error", "Could not rename file.", MessageUtil.MessageType.ERROR, MessageUtil.ImageType.ICON);
                    else contents.setElementAt(name, list.getSelectedIndex());
                }
            }
        });

        newQuiz.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                String name = JOptionPane.showInputDialog(WelcomeGUI.this, "Please enter a name for the quiz.");
                if (name == null) return;
                else name += ".quiz";
                new CreatorGUI(FileManager.getInstance().getFile(name), WelcomeGUI.this);
                WelcomeGUI.this.dispose();
            }
        });

        JScrollPane listPane = new JScrollPane(list);
        listPane.setPreferredSize(new Dimension(500, 125));

        getContentPane().setLayout(new BoxLayout(getContentPane(), BoxLayout.Y_AXIS));
        buttonPanel.setLayout(new BoxLayout(buttonPanel, BoxLayout.Y_AXIS));
        logoPanel.setLayout(new BoxLayout(logoPanel, BoxLayout.Y_AXIS));

        logoPanel.add(logo);
        buttonPanel.add(open); buttonPanel.add(delete); buttonPanel.add(rename); buttonPanel.add(newQuiz);
        contentsPanel.add(listPane); contentsPanel.add(buttonPanel);
        betaPanel.add(betaText);
        add(logoPanel); add(contentsPanel); add(betaPanel);

        Dimension DIM = new Dimension(640, 250);
        setPreferredSize(DIM);
        setSize(DIM);
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        setLocationRelativeTo(null);
        setResizable(false);
        pack();
        setVisible(true);
    }

    public static void main(String[] args) {
        new WelcomeGUI();
    }
}

Answer 1

你可以使用

logo.setAlignmentX(Component.CENTER_ALIGNMENT);