我正在嘗試為我正在研究的想法制作一個登錄頁面，并試圖將兩個按鈕居中。當我獲得螢屏尺寸并將它們除以 2 時，它沒有居中。這是我的代碼：
import javax.swing.*;
import java.awt.*;
public class ChatWindow extends JFrame {
public ChatWindow() {
JFrame frame = new JFrame("EasyChat");
JButton login = new JButton("Login");
JButton signup = new JButton("Don't have an account? Sign Up");
JPanel mainPanel = new JPanel();
Dimension ss = Toolkit.getDefaultToolkit().getScreenSize();
frame.setVisible(true);
frame.setLayout(null);
frame.setSize(800,450);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
frame.getContentPane().add(login);
frame.getContentPane().add(signup);
login.setPreferredSize(new Dimension(25,60));
login.setFont(new Font("HelveticaNeue", Font.BOLD, 20));
signup.setBounds(ss.width / 2, ss.height / 2 125, 200, 100);
login.setBounds(ss.width / 2, ss.height / 2, 200, 100);
mainPanel.setLayout(new BorderLayout());
mainPanel.setBorder(BorderFactory.createEmptyBorder(0, 10, 10, 10));
}
}
我還想知道如果用戶退出全屏模式，如何使按鈕保持居中。
謝謝你。
uj5u.com熱心網友回復：
利用可用的布局管理器。有關更多詳細資訊，請參閱
你可以免費獲得抗拒能力
import java.awt.EventQueue;
import java.awt.GridBagLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
JFrame frame = new JFrame();
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
public TestPane() {
setBorder(new EmptyBorder(16, 16, 16, 16));
setLayout(new GridBagLayout());
add(new JButton("Login"));
add(new JButton("Sign Up"));
}
}
}
現在，如果您希望按鈕相同，您可以使用類似的東西讓它作業GridLayout，
import java.awt.EventQueue;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
JFrame frame = new JFrame();
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
public TestPane() {
setBorder(new EmptyBorder(32, 32, 32, 32));
setLayout(new GridBagLayout());
JPanel buttonPane = new JPanel(new GridLayout(1, -1));
buttonPane.add(new JButton("This is a long button"));
buttonPane.add(new JButton("Sign Up"));
add(buttonPane);
}
}
}
或者您可以使用自定義布局管理器，例如...
import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Insets;
import java.awt.LayoutManager2;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
JFrame frame = new JFrame();
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
public TestPane() {
setBorder(new EmptyBorder(32, 32, 32, 32));
setLayout(new ButtonLayoutManager());
add(new JButton("This is a long button"));
add(new JButton("Sign Up"));
}
}
public class ButtonLayoutManager implements LayoutManager2 {
private int horizontalPadding = 0;
@Override
public void addLayoutComponent(Component comp, Object constraints) {
}
@Override
public void addLayoutComponent(String name, Component comp) {
}
@Override
public void removeLayoutComponent(Component comp) {
}
@Override
public void invalidateLayout(Container target) {
}
@Override
public Dimension maximumLayoutSize(Container target) {
return preferredLayoutSize(target);
}
@Override
public Dimension minimumLayoutSize(Container parent) {
return preferredLayoutSize(parent);
}
@Override
public Dimension preferredLayoutSize(Container parent) {
int height = 0;
int width = 0;
for (Component comp : parent.getComponents()) {
height = Math.max(comp.getPreferredSize().height, height);
width = Math.max(comp.getPreferredSize().width, width);
}
width = (width * parent.getComponentCount()) (horizontalPadding * parent.getComponentCount() - 1);
Insets insets = parent.getInsets();
width = insets.left insets.right;
height = insets.top insets.bottom;
return new Dimension(width, height);
}
@Override
public float getLayoutAlignmentX(Container target) {
return 0.5f;
}
@Override
public float getLayoutAlignmentY(Container target) {
return 0.5f;
}
@Override
public void layoutContainer(Container parent) {
int width = parent.getWidth();
int height = parent.getHeight();
Insets insets = parent.getInsets();
int maxWidth = 0;
int maxHeight = 0;
for (Component comp : parent.getComponents()) {
maxWidth = Math.max(comp.getPreferredSize().width, maxWidth);
maxHeight = Math.max(comp.getPreferredSize().height, maxHeight);
}
int padding = (horizontalPadding * parent.getComponentCount() - 1);
int totalWidth = padding (maxWidth * parent.getComponentCount());
int yOffset = (height - maxHeight) / 2;
int xOffset = (width - totalWidth) / 2;
for (Component comp : parent.getComponents()) {
comp.setBounds(xOffset, yOffset, maxWidth, maxHeight);
xOffset = horizontalPadding maxWidth;
}
}
}
}
注意：我沒有對此進行廣泛的測驗，僅用于演示目的
uj5u.com熱心網友回復：
這個答案似乎使用了 MadProgrammer 詳述的（第一個）方法，但因為我已經準備好了。
import java.awt.*;
import javax.swing.*;
import javax.swing.border.EmptyBorder;
public class CenteredButtons {
public CenteredButtons() {
JFrame f = new JFrame("Centered Buttons");
// A FlowLayout might also be used here
// Doing so would allow each button to be its natural size
JPanel buttonPanel = new JPanel(new GridLayout(1,0,20,20));
buttonPanel.add(new JButton("Yes"));
buttonPanel.add(new JButton("No"));
buttonPanel.setBorder(new EmptyBorder(30,75,30,75));
// a component (e.g. buttonPanel) added with no constraints will be centered
JPanel centerPanel = new JPanel(new GridBagLayout());
centerPanel.add(buttonPanel);
f.setContentPane(centerPanel);
f.pack(); // validates the layout and sets a size for the frame
f.setLocationRelativeTo(null); // centers the window on the screen
f.setExtendedState(JFrame.MAXIMIZED_BOTH); // maximizes the window
f.setVisible(true);
}
public static void main(String[] args) {
Runnable r = () -> new CenteredButtons();
SwingUtilities.invokeLater(r);
}
}
uj5u.com熱心網友回復：
您需要從螢屏尺寸中減去每個按鈕的寬度和高度的一半，以使兩個小部件居中。
將在按鈕上設定邊界的代碼更改為以下內容：
signup.setBounds(ss.width / 2 - 200 / 2, ss.height / 2 125 - 100 / 2, 200, 100);
login.setBounds(ss.width / 2 - 200 / 2, ss.height / 2 - 100 / 2, 200, 100);
要在用戶退出全屏模式時收到通知，請將 a 添加WindowStateListener到框架并重置按鈕的邊界。這是完整的代碼：
import javax.swing.*;
import java.awt.*;
import java.awt.event.WindowEvent;
import java.awt.event.WindowStateListener;
public class ChatWindow extends JFrame implements WindowStateListener{
Dimension ss;
JButton login;
JButton signup;
JFrame frame;
public ChatWindow() {
frame = new JFrame("EasyChat");
frame.addWindowStateListener(this);
login = new JButton("Login");
signup = new JButton("Don't have an account? Sign Up");
JPanel mainPanel = new JPanel();
ss = Toolkit.getDefaultToolkit().getScreenSize();
frame.setVisible(true);
frame.setLayout(null);
frame.setSize(800,450);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
frame.getContentPane().add(login);
frame.getContentPane().add(signup);
login.setPreferredSize(new Dimension(25,60));
login.setFont(new Font("HelveticaNeue", Font.BOLD, 20));
signup.setBounds(ss.width / 2 - 200 / 2, ss.height / 2 125 - 100 / 2, 200, 100);
login.setBounds(ss.width / 2 - 200 / 2, ss.height / 2 - 100 / 2, 200, 100);
mainPanel.setLayout(new BorderLayout());
mainPanel.setBorder(BorderFactory.createEmptyBorder(0, 10, 10, 10));
}
public static void main(String[] args) {
new ChatWindow();
}
@Override
public void windowStateChanged(WindowEvent e) {
Dimension ss = frame.getSize();
signup.setBounds(ss.width / 2 - 200 / 2, ss.height / 2 125 - 100 / 2, 200, 100);
login.setBounds(ss.width / 2 - 200 / 2, ss.height / 2 - 100 / 2, 200, 100);
}
}
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