JLabel，流布局。使 JLabel 居中？
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【中文标题】JLabel，流布局。使 JLabel 居中？【英文标题】：JLabel, FlowLayout. Centering the JLabel? 【发布时间】：2014-08-03 06:36:50 【问题描述】：所以我正在创建这个“彩票”，我尝试了一些不同的方法来将我的 JLabel 的文本居中，但它只是从屏幕中间的右侧开始。这是我的代码和我的意思的图片。
这是我第一次在此表单上发帖，如果我遗漏了什么，请随时纠正我。
代码：
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.HeadlessException;
import javax.swing.JLabel;
import javax.swing.JFrame;
import javax.swing.WindowConstants;
/**
* Author Samy
*/
public class Game extends JFrame
public Game() throws HeadlessException
int width = 720;
int height = width/16*9;
setSize(width,height);
setTitle("The Lottery - V1.0");
setResizable(false);
setLocationRelativeTo(null);
setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
setLayout(new FlowLayout());
String winnings;
double lotteryChance = Math.random()*100;
if (lotteryChance > 50)
winnings = ("You've won $100!");
else if (lotteryChance < 50 && lotteryChance > 20)
winnings = ("You've won $500!");
else if (lotteryChance < 20 && lotteryChance > 5)
winnings = ("You've won $2,000!");
else if (lotteryChance < 5 && lotteryChance > 1)
winnings = ("You've won $5,000!");
else if (lotteryChance < 1 && lotteryChance > 0.1)
winnings = ("You've won $25,000!");
else if (lotteryChance < 0.1 && lotteryChance > 0.01)
winnings = ("You've won $50,000!");
else if (lotteryChance < 0.01 && lotteryChance > 0.001)
winnings = ("You've won $250,000!");
else if (lotteryChance < 0.001 && lotteryChance > 0)
winnings = ("YOU'VE WON THE JACKPOT! $1,000,000!!!");
else winnings = ("Something went wrong, no winnings this round.");
int number = 74;
JLabel label = new JLabel("<html>The Lottery<BR>Authored by: Samy<BR><BR>-=Prize Board=-<BR><BR>100 - 50: $100<BR>50 - 20: $500<BR>20 - 5: $2,000<BR>5 - 1: $5,000<BR>1 - 0.1: $25,000<BR>0.1 - 0.01: $50,000<BR>0.01 - 0.001: $250,000<BR>0.001 - 0.0001: $1,000,000<BR><BR>Your number is: "+lotteryChance+"<BR><BR>"+winnings+"</HTML>");
getContentPane().add(label);
public static void main(String args[])
new Game().setVisible(true);
【问题讨论】：
奖牌应该放在JTable中，以便于阅读。您的奖金范围不应重叠，例如 50。 你建议怎么做？ 【参考方案1】：这是我使用 Swing 组件的彩票游戏版本，以展示 Java Swing 应用程序的外观。
我将所有 Java 类放在一起，以便于复制和粘贴。这些类应该在单独的文件中。
这是我对代码所做的更改。
在 main 方法中，我将启动代码放在 SwingUtilities 的 invokeLater 方法调用中。我这样做是为了将 Swing 组件定义和执行放在 Event Dispatch thread 上。
在 Game 类中，我使用了 JFrame，而不是扩展 JFrame。唯一应该扩展 Swing 组件的时候是在重写其中一个组件方法时。
我创建了两个 JPanel 来放入 JFrame。顶部 JPanel WinningsPanel 包含彩票奖金表。为此，我使用了一个 JTable 来分隔这些值。底部的 JPanel，ButtonPanel，包含一个 JButton，让应用程序生成一个数字并显示彩票奖金。
我创建了两个模型类。第一个模型类 LotteryLine 保存彩票表中一行的值。第二个模型类 GameModel 保存整个彩票表并生成随机数。
我为 JTable 创建了一个彩票表模型。这让我可以控制彩票表中数值的显示。
ButtonPanel 包含一个控制器 PickNumberActionListener，它生成一个随机的彩票号码并显示号码和奖金。
代码如下：
package com.ggl.testing;
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.HeadlessException;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.NumberFormat;
import java.util.ArrayList;
import java.util.List;
import javax.swing.Box;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.SwingUtilities;
import javax.swing.table.AbstractTableModel;
/**
* Author Samy
*/
public class Game
private GameModel model;
private JFrame frame;
public Game() throws HeadlessException
model = new GameModel();
frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setTitle("The Lottery - Version 1.0");
frame.setLocationByPlatform(true);
frame.setLayout(new BorderLayout());
WinningsPanel wPanel = new WinningsPanel(model);
frame.add(wPanel.getPanel(), BorderLayout.NORTH);
ButtonPanel bPanel = new ButtonPanel(model);
frame.add(bPanel.getPanel(), BorderLayout.SOUTH);
frame.pack();
public JFrame getFrame()
return frame;
public static void main(String args[])
SwingUtilities.invokeLater(new Runnable()
@Override
public void run()
new Game().getFrame().setVisible(true);
);
public class LotteryLine
private double lowValue;
private double highValue;
private int prize;
private NumberFormat nf = NumberFormat.getCurrencyInstance();
public LotteryLine(double highValue, double lowValue,
int prize)
this.highValue = highValue;
this.lowValue = lowValue;
this.prize = prize;
public double getLowValue()
return lowValue;
public double getHighValue()
return highValue;
public int getPrize()
return prize;
public String getFormattedPrize()
return nf.format(prize);
public String getLeftPaddedPrize()
StringBuilder builder = new StringBuilder();
String s = getFormattedPrize();
for (int i = s.length(); i < 16; i++)
builder.append(' ');
builder.append(s);
return builder.toString();
public class GameModel
private double randomNumber;
private List<LotteryLine> lotteryList;
public GameModel()
this.lotteryList = new ArrayList<LotteryLine>();
createLotteryList();
private void createLotteryList()
lotteryList.add(new LotteryLine(100D, 50D, 100));
lotteryList.add(new LotteryLine(50D, 20D, 500));
lotteryList.add(new LotteryLine(20D, 5D, 2000));
lotteryList.add(new LotteryLine(5D, 1D, 5000));
lotteryList.add(new LotteryLine(1D, 0.1D, 25000));
lotteryList.add(new LotteryLine(0.1D, 0.01D, 50000));
lotteryList.add(new LotteryLine(0.01D, 0.001D, 250000));
lotteryList.add(new LotteryLine(0.001D, 0.0001D, 1000000));
public double generateRandomNumber()
this.randomNumber = Math.random() * 100D;
return randomNumber;
public List<LotteryLine> getLotteryList()
return lotteryList;
public LotteryLine getLotteryLine(double randomNumber)
for (LotteryLine lotteryLine : lotteryList)
if (randomNumber > lotteryLine.getLowValue())
return lotteryLine;
throw new IllegalArgumentException();
public class WinningsPanel
private GameModel model;
private JPanel panel;
public WinningsPanel(GameModel model)
this.model = model;
createPartControl();
private void createPartControl()
panel = new JPanel();
panel.setLayout(new BorderLayout());
JPanel labelPanel = new JPanel();
labelPanel.setLayout(new BoxLayout(
labelPanel, BoxLayout.PAGE_AXIS));
JLabel writtenLabel = new JLabel("Written by: Samy");
writtenLabel.setAlignmentX(JLabel.CENTER_ALIGNMENT);
labelPanel.add(writtenLabel);
labelPanel.add(Box.createVerticalStrut(20));
JLabel prizeLabel = new JLabel("Prize Table");
prizeLabel.setFont(new Font("default", Font.BOLD, 32));
prizeLabel.setAlignmentX(JLabel.CENTER_ALIGNMENT);
labelPanel.add(prizeLabel);
panel.add(labelPanel, BorderLayout.NORTH);
LotteryTableModel tableModel = new LotteryTableModel(model);
JTable lotteryTable = new JTable(tableModel);
int height = tableModel.getRowCount() *
lotteryTable.getRowHeight();
lotteryTable.setPreferredScrollableViewportSize(
new Dimension(300, height));
JScrollPane scrollPane = new JScrollPane(lotteryTable);
panel.add(scrollPane, BorderLayout.CENTER);
public JPanel getPanel()
return panel;
public class LotteryTableModel extends AbstractTableModel
private static final long serialVersionUID =
7330112393676204265L;
private GameModel model;
private String[] columns = "High Value", "Low Value", "Prize";
public LotteryTableModel(GameModel model)
this.model = model;
@Override
public int getRowCount()
return model.getLotteryList().size();
@Override
public int getColumnCount()
return columns.length;
@Override
public String getColumnName(int columnIndex)
return columns[columnIndex];
@Override
public Class<?> getColumnClass(int column)
switch (column)
case 0:
case 1:
return Double.class;
case 2:
return String.class;
default:
return String.class;
@Override
public Object getValueAt(int rowIndex, int columnIndex)
LotteryLine lotteryLine =
model.getLotteryList().get(rowIndex);
switch (columnIndex)
case 0: return lotteryLine.getHighValue();
case 1: return lotteryLine.getLowValue();
case 2: return lotteryLine.getLeftPaddedPrize();
default: return "";
public class ButtonPanel
private GameModel model;
private JLabel numberLabel;
private JLabel prizeLabel;
private JPanel panel;
public ButtonPanel(GameModel model)
this.model = model;
createPartControl();
private void createPartControl()
panel = new JPanel();
panel.setLayout(new BoxLayout(panel, BoxLayout.PAGE_AXIS));
panel.add(Box.createVerticalStrut(10));
JButton playButton = new JButton("Pick Number");
playButton.addActionListener(new PickNumberActionListener());
playButton.setAlignmentX(JButton.CENTER_ALIGNMENT);
panel.add(playButton);
panel.add(Box.createVerticalStrut(20));
numberLabel = new JLabel(" ");
numberLabel.setAlignmentX(JLabel.CENTER_ALIGNMENT);
panel.add(numberLabel);
prizeLabel = new JLabel(" ");
prizeLabel.setAlignmentX(JLabel.CENTER_ALIGNMENT);
panel.add(prizeLabel);
public void updateNumberLabel(double number)
StringBuilder builder = new StringBuilder();
builder.append("Your number is ");
builder.append(String.format("%.4f", number));
numberLabel.setText(builder.toString());
public void updatePrizeLabel(String prize)
StringBuilder builder = new StringBuilder();
builder.append("You've won ");
builder.append(prize);
prizeLabel.setText(builder.toString());
public JPanel getPanel()
return panel;
public class PickNumberActionListener implements ActionListener
@Override
public void actionPerformed(ActionEvent e)
double number = model.generateRandomNumber();
LotteryLine lotteryLine = model.getLotteryLine(number);
updateNumberLabel(number);
updatePrizeLabel(lotteryLine.getFormattedPrize());
【讨论】：
这看起来很不错，但我在这些方面还不够好，无法理解你所做的一半，但它看起来确实很棒。 @Samy：如果你不接触它，你是不会明白的。将我的代码保存在某个地方并偶尔回来查看它。您最终会掌握其中的大部分内容。【参考方案2】：将FlowLayout.CENTER 传递给alignment 参数的FlowLayout 构造函数。
Here's the constructor doc
例子：
setLayout(new FlowLayout(FlowLayout.CENTER));
编辑：
尝试将<center> HTML 标记添加到标签的 HTML 格式中。这应该使标签中的所有文本居中。
【讨论】：
我试过了，但没有任何改变？你的意思是我应该改变这一行： setLayout(new FlowLayout()); to: setLayout(new FlowLayout(FlowLayout.CENTER)); 对，我自己也试过了，好像没太大变化。尝试在标签文本中添加center 标签。
HTML 部分的中心标签？编辑：这有效！谢啦！ :D以上是关于JLabel，流布局。使 JLabel 居中？的主要内容，如果未能解决你的问题，请参考以下文章