java是否可以使GridBagLayout的JPanel中的元素从左上角开始？

Question

我有一个Swing表单，它包含一个JPanel（activityScrollPane）的JScrollPane（activityPanel）。该面板包含一个JTextField和一个JButton（用于向面板添加更多字段）。现在的问题是，元素从面板的中心开始，如下图所示（边界标记为activityScrollPane边界）

下面是我目前用来制作滚动窗格和相关组件的代码

 //part of the code for creating the ScrollPane

        final JPanel activityPanel = new JPanel(new GridBagLayout());
        gbc.gridx=0;
        gbc.gridy=0;
        JScrollPane activityScrollPane = new JScrollPane(activityPanel); 
        //adding activity fields
        activityFields = new ArrayList<JTextField>();
        fieldIndex = 0;
        activityFields.add(new JTextField(30));

        final GridBagConstraints activityGBC = new GridBagConstraints();
        activityGBC.gridx=0;
        activityGBC.gridy=0;
        activityGBC.anchor = GridBagConstraints.FIRST_LINE_START;
        activityPanel.add(activityFields.get(fieldIndex),activityGBC);

        fieldIndex++;
        JButton btn_more = (new JButton("more"));
        activityGBC.gridx=1;
        activityPanel.add(btn_more,activityGBC);

如何使JTextField和JButton或任何组件显示在JScrollPane的左上角。我已经试过使用

activityConstraints.anchor = GridBagConstraints.NORTHWEST;

正如SO{a1}中所指出的，但它似乎根本不起作用

Answer 1

使用边框布局：controls.setLayout(new BorderLayout());尝试一下，然后将其应用于您的JPanel controls.add(yourPanel, BorderLayout.PAGE_START);

我也有GridBagLayout的问题，所以我用BorderLayout解决了它，而且效果很好

---

所以我为你的小例子写下：

private void initComponents() {

        controls = new Container();
        controls = getContentPane();
        controls.setLayout(new BorderLayout());

        panel = new JPanel();
        panel.setLayout(new GridBagLayout());
        GridBagConstraints c = new GridBagConstraints();

        field = new JTextField(20);
        c.gridx = 0;
        c.gridy = 0;
        panel.add(field, c);

        one = new JButton("Go!");
        c.gridx = 1;
        c.gridy = 0;
        panel.add(one, c);

        controls.add(panel, BorderLayout.PAGE_START);

    }  

希望有帮助

Answer 2

我认为这可能是简单和可能的，你可以

• 将嵌套的JPanel放到JScrollPane

到这个JPanel

• 将JPanels包含JComponent放在GridLayout上（注意滚动，您必须更改滚动增量）

或者使用最复杂的JComponents作为

• 将JPanels包含JComponent作为项目放入JList

• 将JPanels包含JComponent作为行放入JTable（只有一列，有或没有TableHeader）

Answer 3

在右侧和底部分别添加一个面板

右侧面板： 将权重X设置为1.0。 将填充设置为水平

底部面板： 将权重Y设置为1.0。 将填充设置为垂直

也许有更好的方法，但这一种对我有效

Answer 4

很抱歉，我的回答与你的问题不符，但是你为什么不使用GroupLayout而不是GridBag布局呢？这样更容易处理

Answer 5

您只是忘记提供任何weightx/weighty值，至少一个非零值就可以了。请看下面的代码示例：

import java.awt.*;
import javax.swing.*;
public class GridBagLayoutDemo
{
    private JTextField tfield1;
    private JButton button1;

    private void displayGUI()
    {
        JFrame frame = new JFrame("GridBagLayout Demo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel contentPane = new JPanel();
        contentPane.setLayout(new GridBagLayout());

        tfield1 = new JTextField(10);
        GridBagConstraints gbc = new GridBagConstraints();
        gbc.anchor = GridBagConstraints.FIRST_LINE_START;   
        gbc.weightx = 1.0;
        gbc.weighty = 1.0;  
        gbc.gridx = 0;
        gbc.gridy = 0;
        gbc.fill = GridBagConstraints.HORIZONTAL;       
        contentPane.add(tfield1, gbc);

        button1 = new JButton("More");
        gbc.gridx = 1;
        gbc.gridy = 0;
        gbc.fill = GridBagConstraints.NONE;
        contentPane.add(button1, gbc);

        frame.setContentPane(contentPane);
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String... args)
    {
        SwingUtilities.invokeLater(new Runnable()
        {
            public void run()
            {
                new GridBagLayoutDemo().displayGUI();
            }
        });
    }
}

最新编辑：沿Y轴无间距

import java.awt.*;
import javax.swing.*;
public class GridBagLayoutDemo
{
    private JTextField tfield1;
    private JButton button1;
    private JTextField tfield2;
    private JButton button2;

    private void displayGUI()
    {
        JFrame frame = new JFrame("GridBagLayout Demo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel contentPane = new JPanel();
        contentPane.setLayout(new GridBagLayout());

        tfield1 = new JTextField(10);
        GridBagConstraints gbc = new GridBagConstraints();
        gbc.anchor = GridBagConstraints.FIRST_LINE_START;   
        gbc.weightx = 1.0;
        //gbc.weighty = 0.2;    
        gbc.gridx = 0;
        gbc.gridy = 0;
        gbc.fill = GridBagConstraints.HORIZONTAL;       
        contentPane.add(tfield1, gbc);

        button1 = new JButton("More");
        gbc.gridx = 1;
        gbc.gridy = 0;
        gbc.fill = GridBagConstraints.NONE;
        contentPane.add(button1, gbc);

        tfield2 = new JTextField(10);
        gbc.weightx = 1.0;
        gbc.weighty = 0.2;  
        gbc.gridx = 0;
        gbc.gridy = 1;
        gbc.fill = GridBagConstraints.HORIZONTAL;       
        contentPane.add(tfield2, gbc);

        button2 = new JButton("More");
        gbc.gridx = 1;
        gbc.gridy = 1;
        gbc.fill = GridBagConstraints.NONE;
        contentPane.add(button2, gbc);

        JScrollPane scroller = new JScrollPane(contentPane);

        frame.add(scroller);
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String... args)
    {
        SwingUtilities.invokeLater(new Runnable()
        {
            public void run()
            {
                new GridBagLayoutDemo().displayGUI();
            }
        });
    }
}