JPanels内的JButton，填满整个面板 [英] JButtons inside JPanels, fill up the whole panel
问题描述
我一直在努力为插入带有GridLayout的JPanel中的按钮设置特定的大小.
I've been struggling to set a specific size to a button inserted into a JPanel with a GridLayout.
该按钮始终会填满整个面板，而如果删除网格布局，该按钮将不会具有相同的行为.
The button always fills up the whole panel, whereas if I remove the gridlayout, the button won't have the same behavior.
有什么提示吗?
package panels;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class ColorDisplay {
private final int X = 100;
private final int Y = 100;
private final Dimension PANEL_SIZE = new Dimension(500,500);
private JTextField textRed;
private JTextField textGreen;
private JTextField textBlue;
private JLabel labelText, labelRed, labelGreen, labelBlue;
private JPanel displayPanel;
private JPanel textPanel;
private JPanel buttonPanel;
private JButton button;
private final Font font = new Font("Arial", Font.PLAIN, 22);
public static void main(String[] args) {
// TODO Auto-generated method stub
new ColorDisplay();
}
public ColorDisplay(){
JFrame mainFrame = new JFrame();
// make sure the program exits when the frame close
mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mainFrame.setTitle("Color Display");
mainFrame.setLocation(X,Y);
mainFrame.setPreferredSize(PANEL_SIZE);
// ensure an elastic layout
mainFrame.setLayout(new GridLayout(3, 1));
mainFrame.setLocationByPlatform(true);
mainFrame.add(getColorPanel());
mainFrame.add(getTextPanel());
mainFrame.add(getButtonPanel());
mainFrame.pack();
mainFrame.setVisible(true);
}
public JPanel getColorPanel(){
displayPanel = new JPanel(new BorderLayout());
labelText = new JLabel("Color Display", JLabel.CENTER);
Font fontColorDisplay = new Font("Arial", Font.PLAIN, 42);
labelText.setFont(fontColorDisplay);
displayPanel.add(labelText);
return displayPanel;
}
public JPanel getTextPanel(){
textPanel = new JPanel(new GridLayout(2,3));
labelRed = new JLabel("Red", JLabel.CENTER);
labelGreen = new JLabel("Green", JLabel.CENTER);
labelBlue = new JLabel("Blue", JLabel.CENTER);
textRed = new JTextField();
textGreen = new JTextField();
textBlue = new JTextField();
labelRed.setFont(font);
labelGreen.setFont(font);
labelBlue.setFont(font);
textRed.setFont(font);
textGreen.setFont(font);
textBlue.setFont(font);
textPanel.add(labelRed);
textPanel.add(labelGreen);
textPanel.add(labelBlue);
textPanel.add(textRed);
textPanel.add(textGreen);
textPanel.add(textBlue);
return textPanel;
}
public JPanel getButtonPanel(){
buttonPanel = new JPanel(new BorderLayout());
button = new JButton("Display Color");
button.addActionListener(new ButtonListener ()); // Add event handler
button.setFont(font);
button.setPreferredSize(new Dimension(100, 100));
buttonPanel.add(button);
return buttonPanel;
}
private int getColor(){
String colorCode = textRed.getText() + textGreen.getText() + textBlue.getText();
return Integer.parseInt(colorCode);
}
private boolean validateColor(String textValue){
boolean isValid = false;
try {
int num1 = Integer.parseInt(textValue);
if (num1 >= 0 && num1 <= 255)
isValid = true;
else
{
isValid = false;
JOptionPane.showConfirmDialog(null, "Please enter numbers between 0 and 255", "Error", JOptionPane.PLAIN_MESSAGE);
}
} catch (NumberFormatException e) {
JOptionPane.showConfirmDialog(null, "Please enter numerical values", "Error", JOptionPane.PLAIN_MESSAGE);
}
return isValid;
}
private class ButtonListener implements ActionListener { // Inner class
public void actionPerformed(ActionEvent event) {
if (validateColor(textRed.getText()) && validateColor(textGreen.getText()) && validateColor(textBlue.getText()))
{
Color bgColor = new Color(getColor());
displayPanel.setBackground(bgColor);
}
}
}
}
推荐答案
您的问题是关于GridLayout的，但是您使用BorderLayout显示代码:
Your question is about GridLayout but you show code using BorderLayout:
buttonPanel = new JPanel(new BorderLayout());
button = new JButton("Display Color");
button.addActionListener(new ButtonListener ()); // Add event handler
button.setFont(font);
button.setPreferredSize(new Dimension(100, 100));
?
该按钮始终会填满整个面板，而如果我删除 gridlayout，该按钮将不会具有相同的行为.
The button always fills up the whole panel, whereas if I remove the gridlayout, the button won't have the same behavior.
这是GridLayout的默认行为，它的空间被平均分配，并且每个组件都占满了整个空间(BorderLayout会使用相同的空间).
This is GridLayout default behavior, it space is divided equally and each component takes up the full space (same would apply for BorderLayout).
还有许多其他LayoutManager可以满足您的需求:
There are many other LayoutManagers which will will meet your needs:
您可能希望查看 GridBagLayout 更灵活:
You may want to look at GridBagLayout which is more flexible:
buttonPanel = new JPanel(new GridBagLayout());
button = new JButton("Display Color");
button.addActionListener(new ButtonListener()); // Add event handler
button.setFont(font);
GridBagConstraints gc=new GridBagConstraints();
gc.fill=GridBagConstraints.HORIZONTAL;
gc.gridx=0;
gc.gridy=0;
buttonPanel.add(button,gc);
，甚至是默认的JPanel FlowLayout:
buttonPanel = new JPanel();
button = new JButton("Display Color");
button.addActionListener(new ButtonListener()); // Add event handler
button.setFont(font);
buttonPanel.add(button);
或第三方LayoutManger，例如 MigLayout .
Or a 3rd party LayoutManger like MigLayout.
其他建议
-
不要调用
setPreferredSize(..)而不是覆盖getPreferredSize()，甚至不仅仅在绘制到Graphics对象或想要使组件更大/更小时才这样做，不要出于布局目的而这么做，那就是
Dont call
setPreferredSize(..)rather overridegetPreferredSize()and even than only do this when painting to theGraphics object or wanting to make a component bigger/smaller dont do this for Layout purposes thats aLayoutManagers job.
还要始终记住在通过SwingUtilities.invokeLater(Runnable r)块
这篇关于JPanels内的JButton，填满整个面板的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
