java - JLabel、流程布局。将 JLabel 居中？

标签 java text jframe center jlabel

所以我正在创建这个“彩票”，并且我尝试了一些不同的方法来将我的 JLabel 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。

The Lottery

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);
    }
}

最佳答案

这是彩票游戏的一个版本，我在其中使用了 Swing 组件，以展示 Java Swing 应用程序的外观。

enter image description here

我将所有 Java 类放在一起，以便于复制和粘贴。这些类应该位于单独的文件中。

这是我对代码所做的更改。

  1. 在 main 方法中，我将启动代码放在 SwingUtilities invokeLater 方法调用中。我这样做是为了将 Swing 组件的定义和执行放在 Event Dispatch thread 上。 .

  2. 在 Game 类中，我使用了 JFrame，而不是扩展 JFrame。唯一应该扩展 Swing 组件的时候是重写其中一个组件方法时。

  3. 我创建了两个 JPanel 来放入 JFrame 中。顶部 JPanel WinningsPanel 包含彩票奖金表。我使用 JTable 来分隔这些值。底部 JPanel ButtonPanel 包含一个 JButton，用于让应用程序生成一个数字并显示彩票奖金。

  4. 我创建了两个模型类。第一个模型类 LotteryLine 保存彩票表一行的值。第二个模型类 GameModel 保存整个彩票表并生成随机数。

  5. 我为 JTable 创建了一个彩票表模型。这使我能够控制彩票表中数值的显示。

  6. ButtonPanel 包含一个 Controller PickNumberActionListener，它生成随机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());
            }

        }

    }
}

关于java - JLabel、流程布局。将 JLabel 居中？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/24192824/

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