jtextarea 不会用 GridBagConstraints 填充面板

Question

根据我的代码，我希望我的 JTextArea 填充左上边框，如下所示：

但是你可以看到它在中间占据了一小部分。我在包含组件的面板上使用 GridBagConstraints。

有一个主 class 调用了一个 class 框架。此 class 创建 JFrame 并设置大小以及其他内容。然后从扩展了 jframe 的 MainFrame.java 调用它，它创建了 3 个面板并设置了它们的布局。如下所示

import javax.swing.*;
import java.awt.*;

public class MainFrame extends JFrame
{
    private Panel1 storyPanel;
    private Panel2 statsPanel;
    private Panel3 commandsPanel;

    public MainFrame(String title)
    {
        super(title);

        // Setting Layout
        GridBagConstraints gbc = new GridBagConstraints();

        storyPanel = new Panel1();
        storyPanel.setLayout(new GridBagLayout());
        statsPanel = new Panel2();
        commandsPanel = new Panel3();

        Container p = getContentPane();

        p.add(storyPanel, BorderLayout.WEST);
        p.add(statsPanel, BorderLayout.EAST);
        p.add(commandsPanel, BorderLayout.SOUTH);

    }
}

问题中的面板是 Panel1 或 storyPanel。我已经设置了布局，代码调用了 Panel1.java，如下所示：

import javax.swing.*;
import java.awt.*;

public class Panel1 extends JPanel
{
    public Panel1()
    {
        GridBagConstraints gbc = new GridBagConstraints();

        //Set size of Panel1
        int xsizeP1 = (Frame.xsize() / 2);
        int ysizeP1 = (Frame.ysize() / 3 * 2);
        setPreferredSize(new Dimension(xsizeP1, ysizeP1));
        setBorder(BorderFactory.createLineBorder(Color.black));

        //Adding JTextArea and adding settings to it
        JTextArea storyLine = new JTextArea("       test        ");
        storyLine.setLineWrap(true);
        storyLine.setWrapStyleWord(true);
        storyLine.setEditable(false);


        //Adding JScrollPane to the JTextArea and making it have a vertical scrollbar
        JScrollPane scroll = new JScrollPane(storyLine);
        scroll.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
        scroll.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);

        //GridBagConstraints setup for components
        gbc.gridx = 0;
        gbc.gridy = 0;
        gbc.fill = GridBagConstraints.HORIZONTAL;
        gbc.fill = GridBagConstraints.VERTICAL;
        add(scroll, gbc);
    }
}

我不明白为什么我的 gbc.fill 没有让 JTextArea 填充屏幕截图的左上边框。

提前感谢您的任何回复

-汤姆 T

将布局更改为边框布局

import javax.swing.*;
import java.awt.*;

public class Panel1 extends JPanel
{
    public Panel1()
    {
        //GridBagConstraints gbc = new GridBagConstraints();
        //gbc.weightx = 0.1;
        //gbc.weighty = 0.1;
        BorderLayout b = new BorderLayout();

        //Set size of Panel1
        int xsizeP1 = (Frame.xsize() / 2);
        int ysizeP1 = (Frame.ysize() / 3 * 2);
        setPreferredSize(new Dimension(xsizeP1, ysizeP1));
        setBorder(BorderFactory.createLineBorder(Color.black));

        //Adding JTextArea and adding settings to it
        JTextArea storyLine = new JTextArea("       test        ");
        storyLine.setLineWrap(true);
        storyLine.setWrapStyleWord(true);
        storyLine.setEditable(false);


        //Adding JScrollPane to the JTextArea and making it have a vertical scrollbar
        JScrollPane scroll = new JScrollPane(storyLine);
        scroll.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
        scroll.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);

    //gbc.gridx = 0;
    //gbc.gridy = 0;
        //gbc.weightx = 1;
        //gbc.weighty = 1;
        //gbc.fill = GridBagConstraints.BOTH;
        add(scroll, b.CENTER);
    }
}

Answer 1

不要设置 storyPanel 的布局，因为它的内容已经被添加和布局，所以在这里更改布局管理器将丢弃您应用的任何属性。相反，在添加任何组件之前在 Panel1 的构造函数中设置布局。
对 fill 属性使用 GridBagConstraints.BOTH。 fill 属性只能有一个指定值
使用 weightx 和 weighty 指定组件应使用多少可用 space

例如...

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.ScrollPaneConstants;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class MainFrame extends JFrame {

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new MainFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    private Panel1 storyPanel;
//  private Panel2 statsPanel;
//  private Panel3 commandsPanel;

    public MainFrame(String title) {
        super(title);

        storyPanel = new Panel1();

        Container p = getContentPane();

        p.add(storyPanel, BorderLayout.WEST);
        p.add(new JLabel("East"), BorderLayout.EAST);
        p.add(new JLabel("South"), BorderLayout.SOUTH);

    }

    public class Panel1 extends JPanel {

        public Panel1() {
            setLayout(new GridBagLayout());
            GridBagConstraints gbc = new GridBagConstraints();

            //Set size of Panel1
            setBorder(BorderFactory.createLineBorder(Color.black));

            //Adding JTextArea and adding settings to it
            JTextArea storyLine = new JTextArea(20, 20);
            storyLine.setLineWrap(true);
            storyLine.setWrapStyleWord(true);
            storyLine.setEditable(false);

            //Adding JScrollPane to the JTextArea and making it have a vertical scrollbar
            JScrollPane scroll = new JScrollPane(storyLine);
            scroll.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
            scroll.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);

            //GridBagConstraints setup for components
            gbc.gridx = 0;
            gbc.gridy = 0;
            gbc.fill = GridBagConstraints.BOTH;
            gbc.weightx = 1;
            gbc.weighty = 1;
            add(scroll, gbc);
        }
    }
}

话虽如此，BorderLayout 会更简单

public class Panel1 extends JPanel {

    public Panel1() {
        setLayout(new BorderLayout());

        //Set size of Panel1
        setBorder(BorderFactory.createLineBorder(Color.black));

        //Adding JTextArea and adding settings to it
        JTextArea storyLine = new JTextArea(20, 20);
        storyLine.setLineWrap(true);
        storyLine.setWrapStyleWord(true);
        storyLine.setEditable(false);

        //Adding JScrollPane to the JTextArea and making it have a vertical scrollbar
        JScrollPane scroll = new JScrollPane(storyLine);
        scroll.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
        scroll.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);

        add(scroll);
    }
}

i tried a border layout and set it to center expecting it to resize but that failed as well

建议您在某个地方犯了一个根本性错误，因为它对我来说很好用。请记住，在将任何组件添加到容器之前设置布局

jtextarea 不会用 GridBagConstraints 填充面板

jtextarea wont fill panel with GridBagConstraints

java

swing

jtextarea

layout-manager

gridbaglayout