[英]Centering JLabels inside JPanels
I'm making a score-keeping program, but I'm running into a problem. 我正在制作一个计分程序,但是遇到了问题。 What I've tried to do is have a JPanel at the top that contains two JPanels, which, in turn, contains two team names.
我尝试做的是在顶部包含一个JPanel,其中包含两个JPanels,而JPanels又包含两个团队名称。 I'm confused as to why the two JLabels at the top of the program aren't centered inside of the JPanels they're contained in.
我对于为什么程序顶部的两个JLabel不在它们包含的JPanels内部居中感到困惑。
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class ScoreFrame extends JFrame {
private static final Dimension SCREEN_SIZE = Toolkit.getDefaultToolkit().getScreenSize();
private static final int WIDTH = SCREEN_SIZE.width;
private static final int HEIGHT = SCREEN_SIZE.height;
private final JTextField[] nameField = new JTextField[] { new JTextField(), new JTextField() };
private final JLabel[] nameLabel = new JLabel[] { new JLabel("Team 1"), new JLabel("Team 2") };
private final GridBagLayout gridBag = new GridBagLayout();
private final GridBagConstraints constraints = new GridBagConstraints();
private final JPanel topPanel = new JPanel();
public ScoreFrame() {
super();
setResizable(false);
setSize(SCREEN_SIZE);
setLayout(gridBag);
setUndecorated(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
addKeyListener(new EscapeListener());
addComponents();
}
private void addComponents() {
addToTopPanel();
constraints.insets = new Insets(0, 0, (int) (HEIGHT * (double) 4 / 5), 0);
gridBag.setConstraints(topPanel, constraints);
add(topPanel);
}
private void addToTopPanel() {
final JPanel[] teamPanel = new JPanel[] { new JPanel(), new JPanel() };
topPanel.setLayout(gridBag);
topPanel.setSize(new Dimension(WIDTH, HEIGHT / 5));
Dimension teamPanelSize = new Dimension(WIDTH / 2, HEIGHT / 5);
teamPanel[0].setSize(teamPanelSize);
teamPanel[1].setSize(teamPanelSize);
Font nameFont = new Font("Times New Roman", Font.PLAIN, 50);
nameLabel[0].setFont(nameFont);
nameLabel[1].setFont(nameFont);
teamPanel[0].add(nameLabel[0]);
teamPanel[1].add(nameLabel[1]);
gridBag.setConstraints(teamPanel[0], constraints);
constraints.gridx = 1;
gridBag.setConstraints(teamPanel[1], constraints);
topPanel.add(teamPanel[0]);
topPanel.add(teamPanel[1]);
}
public void paint(Graphics g) {
super.paint(g);
int strokeSize = ((WIDTH + HEIGHT) / 2) / 300;
if (strokeSize < 1) {
strokeSize = 1;
}
final int fontSize = (int) (strokeSize * 12.5);
Graphics2D g2d = (Graphics2D) g;
g2d.setStroke(new BasicStroke(strokeSize));
g.drawLine(WIDTH / 2, 0, WIDTH / 2, HEIGHT / 5);
g.drawLine(WIDTH / 2, (int) (HEIGHT * (double) 105 / 400), WIDTH / 2, HEIGHT);
g.drawLine(0, HEIGHT / 5, WIDTH, HEIGHT / 5);
g.drawRect((int) (WIDTH * (double) 45 / 100), HEIGHT / 5, WIDTH / 10, (int) (HEIGHT * (double) 3 / 20));
g2d.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
g.setFont(new Font("Times New Roman", Font.PLAIN, fontSize));
g.drawString("Errors", (int) (WIDTH * (double) 101 / 220), HEIGHT / 4);
}
private JFrame getFrame() {
return this;
}
public static void main(final String args[]) {
new ScoreFrame().setVisible(true);
}
public class EscapeListener implements KeyListener {
public void keyPressed(final KeyEvent event) {
if (event.getKeyCode() == 27) {
final int choice = JOptionPane.showConfirmDialog(getFrame(), "Do you want to exit the program?");
if (choice == 0) {
System.exit(0);
}
}
}
public void keyReleased(final KeyEvent event) {
}
public void keyTyped(final KeyEvent event) {
}
}
}
Invoking pack()
is a critical step in using layouts. 调用
pack()
是使用布局的关键步骤。 This example uses JLabel.CENTER
and GridLayout
to center the labels equally as the frame is resized. 本示例使用
JLabel.CENTER
和GridLayout
在调整框架大小时将标签平均居中。 For simplicity, the center panel is simply a placeholder. 为简单起见,中间面板只是一个占位符。 This somewhat more complex example uses a similar approach along with
java.text.MessageFormat
. 这个稍微复杂一些的示例使用类似的方法以及
java.text.MessageFormat
。
Addendum: But how would I apply pack()
to my code? 附录: 但是如何将
pack()
应用于我的代码?
Simply invoke pack()
as shown in the examples cited. 只需调用引用的示例中所示的
pack()
。 I don't see an easy way to salvage your current approach of setting sizes extrinsically. 我看不到一种简单的方法来挽救您当前在外部设置尺寸的方法。 Instead, override
getPreferredSize()
in a JPanel
for your main content. 而是在
JPanel
重写主要内容的getPreferredSize()
。 No matter the screen size, your implementation of paintComponent()
should adapt to the current size, for example . 无论是屏幕尺寸,你的执行
paintComponent()
应适应当前的大小, 例如 。
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GridLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
/** @see https://stackoverflow.com/a/14422016/230513 */
public class Scores {
private final JLabel[] nameLabel = new JLabel[]{
new JLabel("Team 1", JLabel.CENTER),
new JLabel("Team 2", JLabel.CENTER)};
private void display() {
JFrame f = new JFrame("Scores");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel teamPanel = new JPanel(new GridLayout(1, 0));
teamPanel.add(nameLabel[0]);
teamPanel.add(nameLabel[1]);
f.add(teamPanel, BorderLayout.NORTH);
f.add(new JPanel() {
@Override
public Dimension getPreferredSize() {
return new Dimension(320, 240);
}
}, BorderLayout.CENTER);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
new Scores().display();
}
});
}
}
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