使用四個按鈕，視窗應向四個方向（北、南、東、西）移動，并且視窗不應離開螢屏。這在向北和向西順利運行，但不幸的是在其他方向不行。我猜錯誤出在getEffectiveScreenArea方法中，但我不確定。
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.GraphicsConfiguration;
import java.awt.GraphicsDevice;
import java.awt.GraphicsEnvironment;
import java.awt.Insets;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
public class MoveWindowGUI extends JFrame {
private JButton moveUp, moveDown, moveLeft, moveRight;
private int x, y;
public MoveWindowGUI(String title) {
super(title);
this.initializeButtons();
this.prepareWindow();
this.addActionListener();
pack();
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setVisible(true);
}
private void initializeButtons() {
this.moveUp = new JButton("U");
this.moveDown = new JButton("D");
this.moveLeft = new JButton("L");
this.moveRight = new JButton("R");
}
private void prepareWindow() {
setLayout(new BorderLayout(25, 25));
this.addComponents();
this.centerWindow();
setSize(300, 300);
}
private void centerWindow() {
Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
Dimension windowSize = getSize();
int centralWidth = (screenSize.width - windowSize.width) / 2;
int centralHeight = (screenSize.height - windowSize.height) / 2;
setLocation(centralWidth, centralHeight);
}
private void addComponents() {
add(this.moveUp, BorderLayout.NORTH);
add(this.moveDown, BorderLayout.SOUTH);
add(this.moveLeft, BorderLayout.WEST);
add(this.moveRight, BorderLayout.EAST);
}
private void addActionListener() {
ActionListener listener = new WindowActionListener();
moveUp.addActionListener(listener);
moveDown.addActionListener(listener);
moveLeft.addActionListener(listener);
moveRight.addActionListener(listener);
}
class WindowActionListener implements ActionListener {
@Override
public void actionPerformed(ActionEvent e) {
String command = e.getActionCommand();
if (command.equals("U")) {
y -= 10;
} else if (command.equals("D")) {
y = 10;
} else if (command.equals("L")) {
x -= 10;
} else if (command.equals("R")) {
x = 10;
}
this.refreshWindow();
}
private void refreshWindow() {
Point lastLocation = getLocation();
Rectangle effectiveScreenArea = getEffectiveScreenArea();
int newX = lastLocation.x x;
int newY = lastLocation.y y;
if (newX < effectiveScreenArea.x) {
newX = effectiveScreenArea.x;
} else if (newY < effectiveScreenArea.y) {
newY = effectiveScreenArea.y;
} else if (newX >= effectiveScreenArea.width) {
newX = effectiveScreenArea.width;
} else if (newY >= effectiveScreenArea.height) {
newY = effectiveScreenArea.height;
}
setLocation(newX, newY);
this.resetHeightAndWitdhLocally();
pack();
}
public Rectangle getEffectiveScreenArea() {
int minX = 0, minY = 0, maxX = 0, maxY = 0;
GraphicsEnvironment environment = GraphicsEnvironment.getLocalGraphicsEnvironment();
int screenDevices = environment.getScreenDevices().length;
for(GraphicsDevice device : environment.getScreenDevices()) {
Rectangle bounds = device.getDefaultConfiguration().getBounds();
minX = Math.min(minX, bounds.x);
minY = Math.min(minY, bounds.y);
maxX = Math.max(maxX, bounds.x bounds.width);
maxY = Math.max(maxY, bounds.y bounds.height);
}
return new Rectangle(minX, minY, (maxX - minX) / screenDevices, (maxY - minY) / screenDevices);
}
/*
private Rectangle getEffectiveScreenArea() {
GraphicsConfiguration graphicsConfiguration = getGraphicsConfiguration();
Rectangle bounds = graphicsConfiguration.getBounds();
Insets screenInsets = Toolkit.getDefaultToolkit().getScreenInsets(graphicsConfiguration);
Rectangle effectiveScreenArea = new Rectangle();
effectiveScreenArea.x = bounds.x screenInsets.left;
effectiveScreenArea.y = bounds.y screenInsets.top;
effectiveScreenArea.height = bounds.height screenInsets.top - screenInsets.bottom;
effectiveScreenArea.width = bounds.width - screenInsets.left - screenInsets.right;
return effectiveScreenArea;
}
*/
private void resetHeightAndWitdhLocally() {
x = 0;
y = 0;
}
}
}
uj5u.com熱心網友回復：
我拿了你的代碼并對它做了一些修改。這是我創建的 GUI。
我把JButtons上JPanel。然后，我把JPanel上JFrame。通常，將 Swing 組件放在 上JPanel而不是直接放在上是個好主意JFrame。
我打掃了WindowActionListener班級。
這是完整的可運行代碼。我將WindowActionListener類設為內部類，以便可以將此代碼作為一個塊發布。
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.GraphicsDevice;
import java.awt.GraphicsEnvironment;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class MoveWindowGUI implements Runnable {
public static void main(String[] args) {
SwingUtilities.invokeLater(new MoveWindowGUI());
}
private JFrame frame;
@Override
public void run() {
frame = new JFrame("Move Window GUI");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(createMainPanel(), BorderLayout.CENTER);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
private JPanel createMainPanel() {
JPanel panel = new JPanel(new BorderLayout());
panel.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
WindowActionListener listener = new WindowActionListener(this);
JButton upButton = new JButton("Up");
upButton.addActionListener(listener);
panel.add(upButton, BorderLayout.NORTH);
JButton downButton = new JButton("Down");
downButton.addActionListener(listener);
panel.add(downButton, BorderLayout.SOUTH);
JButton leftButton = new JButton("Left");
leftButton.addActionListener(listener);
panel.add(leftButton, BorderLayout.WEST);
JButton rightButton = new JButton("Right");
rightButton.addActionListener(listener);
panel.add(rightButton, BorderLayout.EAST);
Dimension d = panel.getPreferredSize();
d.width = 300;
panel.setPreferredSize(d);
return panel;
}
public JFrame getFrame() {
return frame;
}
public class WindowActionListener implements ActionListener {
private final MoveWindowGUI view;
public WindowActionListener(MoveWindowGUI view) {
this.view = view;
}
@Override
public void actionPerformed(ActionEvent event) {
String command = event.getActionCommand();
int increment = 100;
switch (command) {
case "Up":
refreshWindow(0, -increment);
break;
case "Down":
refreshWindow(0, increment);
break;
case "Left":
refreshWindow(-increment, 0);
break;
case "Right":
refreshWindow(increment, 0);
break;
}
}
private void refreshWindow(int deltaX, int deltaY) {
Rectangle frameArea = view.getFrame().getBounds();
Rectangle screenArea = getEffectiveScreenArea();
int x = frameArea.x;
int y = frameArea.y;
int minX = screenArea.x;
int minY = screenArea.y;
int maxX = screenArea.width - frameArea.width;
int maxY = screenArea.height - frameArea.height;
x = deltaX;
y = deltaY;
x = Math.max(minX, x);
x = Math.min(maxX, x);
y = Math.max(minY, y);
y = Math.min(maxY, y);
view.getFrame().setBounds(new Rectangle(x, y, frameArea.width, frameArea.height));
}
private Rectangle getEffectiveScreenArea() {
int minX = 0, minY = 0, maxX = 0, maxY = 0;
GraphicsEnvironment environment = GraphicsEnvironment.getLocalGraphicsEnvironment();
int screenDevices = environment.getScreenDevices().length;
for (GraphicsDevice device : environment.getScreenDevices()) {
Rectangle bounds = device.getDefaultConfiguration().getBounds();
minX = Math.min(minX, bounds.x);
minY = Math.min(minY, bounds.y);
maxX = Math.max(maxX, bounds.x bounds.width);
maxY = Math.max(maxY, bounds.y bounds.height);
}
return new Rectangle(minX, minY, (maxX - minX) / screenDevices,
(maxY - minY) / screenDevices);
}
}
}
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