java JPanels里面的JButtons，填满整个面板

Question

提问by pelican_george

I've been struggling to set a specific size to a button inserted into a JPanel with a GridLayout.

我一直在努力为插入带有 GridLayout 的 JPanel 的按钮设置特定大小。

The button always fills up the whole panel, whereas if I remove the gridlayout, the button won't have the same behavior.

该按钮始终填满整个面板，而如果我删除 gridlayout，该按钮将不会具有相同的行为。

any hints?

任何提示？

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);    
        }


    }
}
}

Answer 1

回答by David Kroukamp

Your question is about GridLayoutbut you show code using BorderLayout:

您的问题是关于GridLayout但您使用BorderLayout以下代码显示代码：

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));

?

The button always fills up the whole panel, whereas if I remove the gridlayout, the button won't have the same behavior.

该按钮始终填满整个面板，而如果我删除 gridlayout，该按钮将不会具有相同的行为。

This is GridLayoutdefault behavior, it space is divided equally and each component takes up the full space (same would apply for BorderLayout).

这是GridLayout默认行为，它的空间被平均划分，每个组件都占据整个空间（同样适用于BorderLayout）。

There are many other LayoutManagers which will will meet your needs:

还有许多其他LayoutManagers 将满足您的需求：

A Visual Guide to Layout Managers

布局管理器的视觉指南

You may want to look at GridBagLayoutwhich is more flexible:

您可能想看看GridBagLayout哪个更灵活：

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);

enter image description here

在此处输入图片说明

or even the default JPanelFlowLayout:

甚至是默认值JPanelFlowLayout：

    buttonPanel = new JPanel();
    button = new JButton("Display Color");
    button.addActionListener(new ButtonListener()); // Add event handler
    button.setFont(font);

    buttonPanel.add(button);

enter image description here

在此处输入图片说明

Or a 3rd party LayoutMangerlike MigLayout.

或者LayoutManger像MigLayout.

Other suggestions:

其他建议：

Dont call setPreferredSize(..)rather override getPreferredSize()and even than only do this when painting to the Graphics object or wanting to make a component bigger/smaller dont do this for Layout purposes thats a LayoutManagers job.
Also always remember to create and manipulate Swing components on the Event Dispatch Threadvia SwingUtilities.invokeLater(Runnable r)block

不要调用setPreferredSize(..)而是覆盖getPreferredSize()，甚至不要只在绘制到Graphics 对象或想要使组件更大/更小时才这样做，不要为了布局目的而这样做，这是一项LayoutManagers 工作。
还要永远记住通过块在事件调度线程上创建和操作 Swing 组件SwingUtilities.invokeLater(Runnable r)

Answer 2

回答by c.pramod

Replace your getButtonPanel() with this method ( I've used GroupLayout to make it work),

用这个方法替换你的 getButtonPanel()（我使用 GroupLayout 让它工作），

public JPanel getButtonPanel(){

    JPanel jPanel1 = new JPanel();
    button = new JButton("Display Color");
    button.addActionListener(new ButtonListener ()); // Add event handler
    button.setFont(font);
    javax.swing.GroupLayout jPanel1Layoutx = new javax.swing.GroupLayout(jPanel1);
                    jPanel1.setLayout(jPanel1Layoutx);
                    jPanel1Layoutx.setHorizontalGroup(
                            jPanel1Layoutx.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING).addGroup(jPanel1Layoutx.createSequentialGroup().addContainerGap().addComponent(button, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE).addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)));
                    jPanel1Layoutx.setVerticalGroup(
                            jPanel1Layoutx.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING).addGroup(jPanel1Layoutx.createSequentialGroup().addComponent(button, javax.swing.GroupLayout.PREFERRED_SIZE, 24, javax.swing.GroupLayout.PREFERRED_SIZE).addGap(0, 12, Short.MAX_VALUE)));

    return jPanel1;

}

Instead of 24 u can set button size that u prefer !

您可以设置您喜欢的按钮大小而不是 24 个！

Answer 3

回答by DarrenKing

Simply create a JPanel, and add that JPanel to the layout of the frame. Now inside that JPanel, lets call it holderPanel, you add the button. Now the button doesn't take up the entire space! Feel free to do some of the following to better suite your program:

只需创建一个 JPanel，并将该 JPanel 添加到框架的布局中。现在在 JPanel 中，我们称其为 holderPanel，然后添加按钮。现在按钮不会占据整个空间！随意执行以下一些操作以更好地适应您的程序：

holderPanel.setOpaque(false); //So the panel is invisible, but your button is
holderPanel.setBorder(new EmptyBorder(80, 50, 20, 130));

holderPanel.setOpaque(false); //So the panel is invisible, but your button is
holderPanel.setBorder(new EmptyBorder(80, 50, 20, 130));

Answer 4

回答by MMSA

Try this, it worked for me.

试试这个，它对我有用。

JFrame frame=new JFrame();
JPanel p1 = new JPanel(new GridLayout(2,1));
JLabel lb1= new JLabel("Test1");
JButton button1 = new JButton("Go to whatever");
button1.addActionListener();
JPanel p2=new JPanel();
p2.add(button1);
p1.add(p2);
frame.add(p1);

java JPanels里面的JButtons，填满整个面板

提问by pelican_george

回答by David Kroukamp

回答by c.pramod

回答by DarrenKing

回答by MMSA

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java JPanels里面的JButtons，填满整个面板

提问by pelican_george

回答by David Kroukamp

回答by c.pramod

回答by DarrenKing

回答by MMSA

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