如何消除 JButton 行边缘和父 JPanel 边缘之间的间隙？
How to remove gap between edge of JButton rows and edge of parent JPanel?
我正在用 Swing 制作一个计算器作为练习，我不明白为什么 JButton 行的边缘和父 JPanel 的边缘之间有这个间隙 (buttonPanel)。我查看了我的代码并更改了一些东西，但我仍然无法弄清楚为什么会有差距。如果我删除 MatteBorder，将边框保留为默认值，间隙就会消失，但按钮之间会有双边框。如果我将 JTextField 的列大小减少到 7，那么差距就会消失。我如何才能在不使用双边框或缩小我的应用程序的情况下解决这个问题？
（我将面板的背景设置为红色以帮助确定是哪个组件导致了间隙。）
public class CalculatorView extends JFrame {
// NOTE: Not recommended to extend JFrame, recommended to use composition over inheritance
private JTextField display = new JTextField("0", 17);
// Number buttons
private JButton zeroButton = new JButton("0");
private JButton oneButton = new JButton("1");
private JButton twoButton = new JButton("2");
private JButton threeButton = new JButton("3");
private JButton fourButton = new JButton("4");
private JButton fiveButton = new JButton("5");
private JButton sixButton = new JButton("6");
private JButton sevenButton = new JButton("7");
private JButton eightButton = new JButton("8");
private JButton nineButton = new JButton("9");
private JButton periodButton = new JButton(".");
// Operation buttons
private JButton additionButton = new JButton("+");
private JButton subtractionButton = new JButton("-");
private JButton divisionButton = new JButton("÷");
private JButton multiplicationButton = new JButton("x");
private JButton signChangeButton = new JButton("+/-");
private JButton percentButton = new JButton("%");
private JButton clearButton = new JButton("AC");
private JButton equalButton = new JButton("=");
CalculatorView() {
// Set the look and feel to the cross-platform look and feel,
// otherwise mac os will have quirks like gaps between jbuttons
try {
UIManager.setLookAndFeel(UIManager.getCrossPlatformLookAndFeelClassName());
} catch (Exception e) {
System.err.println("Unsupported look and feel.");
e.printStackTrace();
}
// Let the OS set location, prevent user from resizing window, and exit app on close
this.setLocationByPlatform(true);
this.setResizable(false);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setUndecorated(true); // must be undecorated for setbackground to work
// Create the main panel, which by default covers the entire frame
// NOTE: Good practice. Never put components directly onto a JFrame.
JPanel gui = new JPanel();
// Set the main panel's layout manager to BorderLayout
gui.setLayout(new BorderLayout());
// Create the button panel
JPanel buttonPanel = new JPanel();
// Set button panel's layout manager to GridBagLayout
buttonPanel.setLayout(new GridBagLayout());
// Create a GridBagConstraints object to control the layout of components
GridBagConstraints c = new GridBagConstraints();
c.insets = new Insets(0, 0, 0, 0);
c.fill = GridBagConstraints.HORIZONTAL;
// Position buttons on the grid
c.gridx = 0;
c.gridy = 0;
c.ipady = 30; // adjust vertical height of buttons
c.weightx = 1; // needed or buttons will cluster at center w/ gap on sides
buttonPanel.add(clearButton, c);
clearButton.setBackground(Color.gray);
clearButton.setOpaque(true);
clearButton.setBorder(new MatteBorder(0, 1, 0, 1, Color.BLACK));
c.gridx = 1;
buttonPanel.add(signChangeButton, c);
signChangeButton.setBackground(Color.gray);
signChangeButton.setOpaque(true);
signChangeButton.setBorder(new MatteBorder(0, 0, 0, 1, Color.BLACK));
c.gridx = 2;
buttonPanel.add(percentButton, c);
percentButton.setBackground(Color.gray);
percentButton.setOpaque(true);
percentButton.setBorder(new MatteBorder(0, 0, 0, 1, Color.BLACK));
c.gridx = 3;
buttonPanel.add(divisionButton, c);
divisionButton.setBackground(Color.ORANGE);
divisionButton.setOpaque(true);
divisionButton.setBorder(new MatteBorder(0, 0, 0, 1, Color.BLACK));
c.gridx = 0;
c.gridy = 1;
buttonPanel.add(sevenButton, c);
sevenButton.setBorder(new MatteBorder(1, 1, 0, 1, Color.BLACK));
c.gridx = 1;
buttonPanel.add(eightButton, c);
eightButton.setBorder(new MatteBorder(1, 0, 0, 1, Color.BLACK));
c.gridx = 2;
buttonPanel.add(nineButton, c);
nineButton.setBorder(new MatteBorder(1, 0, 0, 1, Color.BLACK));
c.gridx = 3;
buttonPanel.add(multiplicationButton, c);
multiplicationButton.setBackground(Color.ORANGE);
multiplicationButton.setOpaque(true);
multiplicationButton.setBorder(new MatteBorder(1, 0, 0, 1, Color.BLACK));
c.gridx = 0;
c.gridy = 2;
buttonPanel.add(fourButton, c);
fourButton.setBorder(new MatteBorder(1, 1, 0, 1, Color.BLACK));
c.gridx = 1;
buttonPanel.add(fiveButton, c);
fiveButton.setBorder(new MatteBorder(1, 0, 0, 1, Color.BLACK));
c.gridx = 2;
buttonPanel.add(sixButton, c);
sixButton.setBorder(new MatteBorder(1, 0, 0, 1, Color.BLACK));
c.gridx = 3;
buttonPanel.add(subtractionButton, c);
subtractionButton.setBackground(Color.ORANGE);
subtractionButton.setOpaque(true);
subtractionButton.setBorder(new MatteBorder(1, 0, 0, 1, Color.BLACK));
c.gridx = 0;
c.gridy = 3;
buttonPanel.add(oneButton, c);
oneButton.setBorder(new MatteBorder(1, 1, 0, 1, Color.BLACK));
c.gridx = 1;
buttonPanel.add(twoButton, c);
twoButton.setBorder(new MatteBorder(1, 0, 0, 1, Color.BLACK));
c.gridx = 2;
buttonPanel.add(threeButton, c);
threeButton.setBorder(new MatteBorder(1, 0, 0, 1, Color.BLACK));
c.gridx = 3;
buttonPanel.add(additionButton, c);
additionButton.setBackground(Color.ORANGE);
additionButton.setOpaque(true);
additionButton.setBorder(new MatteBorder(1, 0, 0, 1, Color.BLACK));
c.gridx = 0;
c.gridy = 4;
c.gridwidth = 2; // spans 2 cells
buttonPanel.add(zeroButton, c);
zeroButton.setBorder(new MatteBorder(1, 1, 1, 1, Color.BLACK));
c.gridx = 2;
c.gridwidth = 1;
buttonPanel.add(periodButton, c);
periodButton.setBorder(new MatteBorder(1, 0, 1, 1, Color.BLACK));
c.gridx = 3;
buttonPanel.add(equalButton, c);
equalButton.setBackground(Color.ORANGE);
equalButton.setOpaque(true);
equalButton.setBorder(new MatteBorder(1, 0, 1, 1, Color.BLACK));
// Customize display field
display.setHorizontalAlignment(JTextField.RIGHT);
display.setFont(new Font("Arial", Font.PLAIN, 40));
display.setBorder(new EmptyBorder(30, 0, 0, 0));
display.setForeground(Color.WHITE);
// Make display translucent but leave button panel opaque
this.setBackground(new Color(0, 0, 0, 100));
gui.setBackground(new Color(0,0,0,100));
display.setBackground(new Color(0, 0, 0, 100));
// I need to fix the gap between the edge of the buttonPanel and the buttons...
buttonPanel.setBackground(Color.red);
// Add display and button panel to main panel, then main panel to frame
gui.add(display, BorderLayout.NORTH);
gui.add(buttonPanel, BorderLayout.CENTER);
this.add(gui);
this.pack();
}
}
检查每条在 Y 轴上为 GridBagConstraints 分配填充的语句，即
c.ipady = 30;
尝试移除或减少它们
不知道为什么会有这个空隙，如果你设置了下面的空边框，背景就没有了：
JPanel buttonPanel = new JPanel();
// Set button panel's layout manager to GridBagLayout
buttonPanel.setLayout(new GridBagLayout());
buttonPanel.setBorder(new EmptyBorder(0, -1, 0, -1));
我正在用 Swing 制作一个计算器作为练习，我不明白为什么 JButton 行的边缘和父 JPanel 的边缘之间有这个间隙 (buttonPanel)。我查看了我的代码并更改了一些东西，但我仍然无法弄清楚为什么会有差距。如果我删除 MatteBorder，将边框保留为默认值，间隙就会消失，但按钮之间会有双边框。如果我将 JTextField 的列大小减少到 7，那么差距就会消失。我如何才能在不使用双边框或缩小我的应用程序的情况下解决这个问题？
（我将面板的背景设置为红色以帮助确定是哪个组件导致了间隙。）
public class CalculatorView extends JFrame {
// NOTE: Not recommended to extend JFrame, recommended to use composition over inheritance
private JTextField display = new JTextField("0", 17);
// Number buttons
private JButton zeroButton = new JButton("0");
private JButton oneButton = new JButton("1");
private JButton twoButton = new JButton("2");
private JButton threeButton = new JButton("3");
private JButton fourButton = new JButton("4");
private JButton fiveButton = new JButton("5");
private JButton sixButton = new JButton("6");
private JButton sevenButton = new JButton("7");
private JButton eightButton = new JButton("8");
private JButton nineButton = new JButton("9");
private JButton periodButton = new JButton(".");
// Operation buttons
private JButton additionButton = new JButton("+");
private JButton subtractionButton = new JButton("-");
private JButton divisionButton = new JButton("÷");
private JButton multiplicationButton = new JButton("x");
private JButton signChangeButton = new JButton("+/-");
private JButton percentButton = new JButton("%");
private JButton clearButton = new JButton("AC");
private JButton equalButton = new JButton("=");
CalculatorView() {
// Set the look and feel to the cross-platform look and feel,
// otherwise mac os will have quirks like gaps between jbuttons
try {
UIManager.setLookAndFeel(UIManager.getCrossPlatformLookAndFeelClassName());
} catch (Exception e) {
System.err.println("Unsupported look and feel.");
e.printStackTrace();
}
// Let the OS set location, prevent user from resizing window, and exit app on close
this.setLocationByPlatform(true);
this.setResizable(false);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setUndecorated(true); // must be undecorated for setbackground to work
// Create the main panel, which by default covers the entire frame
// NOTE: Good practice. Never put components directly onto a JFrame.
JPanel gui = new JPanel();
// Set the main panel's layout manager to BorderLayout
gui.setLayout(new BorderLayout());
// Create the button panel
JPanel buttonPanel = new JPanel();
// Set button panel's layout manager to GridBagLayout
buttonPanel.setLayout(new GridBagLayout());
// Create a GridBagConstraints object to control the layout of components
GridBagConstraints c = new GridBagConstraints();
c.insets = new Insets(0, 0, 0, 0);
c.fill = GridBagConstraints.HORIZONTAL;
// Position buttons on the grid
c.gridx = 0;
c.gridy = 0;
c.ipady = 30; // adjust vertical height of buttons
c.weightx = 1; // needed or buttons will cluster at center w/ gap on sides
buttonPanel.add(clearButton, c);
clearButton.setBackground(Color.gray);
clearButton.setOpaque(true);
clearButton.setBorder(new MatteBorder(0, 1, 0, 1, Color.BLACK));
c.gridx = 1;
buttonPanel.add(signChangeButton, c);
signChangeButton.setBackground(Color.gray);
signChangeButton.setOpaque(true);
signChangeButton.setBorder(new MatteBorder(0, 0, 0, 1, Color.BLACK));
c.gridx = 2;
buttonPanel.add(percentButton, c);
percentButton.setBackground(Color.gray);
percentButton.setOpaque(true);
percentButton.setBorder(new MatteBorder(0, 0, 0, 1, Color.BLACK));
c.gridx = 3;
buttonPanel.add(divisionButton, c);
divisionButton.setBackground(Color.ORANGE);
divisionButton.setOpaque(true);
divisionButton.setBorder(new MatteBorder(0, 0, 0, 1, Color.BLACK));
c.gridx = 0;
c.gridy = 1;
buttonPanel.add(sevenButton, c);
sevenButton.setBorder(new MatteBorder(1, 1, 0, 1, Color.BLACK));
c.gridx = 1;
buttonPanel.add(eightButton, c);
eightButton.setBorder(new MatteBorder(1, 0, 0, 1, Color.BLACK));
c.gridx = 2;
buttonPanel.add(nineButton, c);
nineButton.setBorder(new MatteBorder(1, 0, 0, 1, Color.BLACK));
c.gridx = 3;
buttonPanel.add(multiplicationButton, c);
multiplicationButton.setBackground(Color.ORANGE);
multiplicationButton.setOpaque(true);
multiplicationButton.setBorder(new MatteBorder(1, 0, 0, 1, Color.BLACK));
c.gridx = 0;
c.gridy = 2;
buttonPanel.add(fourButton, c);
fourButton.setBorder(new MatteBorder(1, 1, 0, 1, Color.BLACK));
c.gridx = 1;
buttonPanel.add(fiveButton, c);
fiveButton.setBorder(new MatteBorder(1, 0, 0, 1, Color.BLACK));
c.gridx = 2;
buttonPanel.add(sixButton, c);
sixButton.setBorder(new MatteBorder(1, 0, 0, 1, Color.BLACK));
c.gridx = 3;
buttonPanel.add(subtractionButton, c);
subtractionButton.setBackground(Color.ORANGE);
subtractionButton.setOpaque(true);
subtractionButton.setBorder(new MatteBorder(1, 0, 0, 1, Color.BLACK));
c.gridx = 0;
c.gridy = 3;
buttonPanel.add(oneButton, c);
oneButton.setBorder(new MatteBorder(1, 1, 0, 1, Color.BLACK));
c.gridx = 1;
buttonPanel.add(twoButton, c);
twoButton.setBorder(new MatteBorder(1, 0, 0, 1, Color.BLACK));
c.gridx = 2;
buttonPanel.add(threeButton, c);
threeButton.setBorder(new MatteBorder(1, 0, 0, 1, Color.BLACK));
c.gridx = 3;
buttonPanel.add(additionButton, c);
additionButton.setBackground(Color.ORANGE);
additionButton.setOpaque(true);
additionButton.setBorder(new MatteBorder(1, 0, 0, 1, Color.BLACK));
c.gridx = 0;
c.gridy = 4;
c.gridwidth = 2; // spans 2 cells
buttonPanel.add(zeroButton, c);
zeroButton.setBorder(new MatteBorder(1, 1, 1, 1, Color.BLACK));
c.gridx = 2;
c.gridwidth = 1;
buttonPanel.add(periodButton, c);
periodButton.setBorder(new MatteBorder(1, 0, 1, 1, Color.BLACK));
c.gridx = 3;
buttonPanel.add(equalButton, c);
equalButton.setBackground(Color.ORANGE);
equalButton.setOpaque(true);
equalButton.setBorder(new MatteBorder(1, 0, 1, 1, Color.BLACK));
// Customize display field
display.setHorizontalAlignment(JTextField.RIGHT);
display.setFont(new Font("Arial", Font.PLAIN, 40));
display.setBorder(new EmptyBorder(30, 0, 0, 0));
display.setForeground(Color.WHITE);
// Make display translucent but leave button panel opaque
this.setBackground(new Color(0, 0, 0, 100));
gui.setBackground(new Color(0,0,0,100));
display.setBackground(new Color(0, 0, 0, 100));
// I need to fix the gap between the edge of the buttonPanel and the buttons...
buttonPanel.setBackground(Color.red);
// Add display and button panel to main panel, then main panel to frame
gui.add(display, BorderLayout.NORTH);
gui.add(buttonPanel, BorderLayout.CENTER);
this.add(gui);
this.pack();
}
}
检查每条在 Y 轴上为 GridBagConstraints 分配填充的语句，即
c.ipady = 30;
尝试移除或减少它们
不知道为什么会有这个空隙，如果你设置了下面的空边框，背景就没有了：
JPanel buttonPanel = new JPanel();
// Set button panel's layout manager to GridBagLayout
buttonPanel.setLayout(new GridBagLayout());
buttonPanel.setBorder(new EmptyBorder(0, -1, 0, -1));