GridBagConstraints gridheight和gridwidth

Question

使用GridBagLayout，我正在尝试安排我的组件：

但是这些组件就像这样，所有组合在一起的东西：

我以前从未使用GridBagConstraints字段gridwidth和gridheight。我做错了什么？这是一个SSCCE：

import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.*;

public class GUI extends JFrame {

    private GridBagLayout gridBag = new GridBagLayout();
    GridBagConstraints constraints = new GridBagConstraints();
    private static final String[] ALL_STRINGS = { "B", "A", "C" };

    private JButton leftButton = new JButton("<");
    private JButton rightButton = new JButton(">");
    private JList<String> list = new JList<String>(ALL_STRINGS);
    private JList<String> queue = new JList<String>();
    private JPanel selectionPanel = new JPanel(gridBag);
    private JCheckBox filterBox = new JCheckBox("filterBox");
    private JButton clear = new JButton("Clear");

    public GUI() {
        setWindowProperties();
        addComponents();
    }

    private void setWindowProperties() {
        setLayout(gridBag);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(new Dimension(400, 400));
        setTitle("GridBagLayout issues");
        setResizable(false);
        setLocationRelativeTo(null);
    }

    private void setUpSelectionPanel() {
        JLabel listLabel = new JLabel("Quest List");
        JLabel queueLabel = new JLabel("Queue");
        JScrollPane listScroll = new JScrollPane(list);
        JScrollPane queueScroll = new JScrollPane(queue);
        Dimension scrollSize = new Dimension(150, 300);
        listScroll.setPreferredSize(scrollSize);
        queueScroll.setPreferredSize(scrollSize);

        constraints.gridx = 0;
        constraints.gridy = 0;
        gridBag.setConstraints(listLabel, constraints);

        constraints.gridx = 0;
        constraints.gridy = 1;
        constraints.gridwidth = 2;
        constraints.gridheight = 3;
        gridBag.setConstraints(listScroll, constraints);

        constraints.gridx = 2;
        constraints.gridy = 1;
        gridBag.setConstraints(filterBox, constraints);

        constraints.gridx = 2;
        constraints.gridy = 2;
        gridBag.setConstraints(leftButton, constraints);

        constraints.gridx = 2;
        constraints.gridy = 3;
        gridBag.setConstraints(rightButton, constraints);

        constraints.gridx = 2;
        constraints.gridy = 4;
        gridBag.setConstraints(clear, constraints);

        constraints.gridx = 3;
        constraints.gridy = 0;
        gridBag.setConstraints(queueLabel, constraints);

        constraints.gridx = 3;
        constraints.gridy = 1;
        constraints.gridwidth = 2;
        constraints.gridheight = 3;
        gridBag.setConstraints(queueScroll, constraints);

        selectionPanel.add(listLabel);
        selectionPanel.add(listScroll);
        selectionPanel.add(filterBox);
        selectionPanel.add(leftButton);
        selectionPanel.add(rightButton);
        selectionPanel.add(clear);
        selectionPanel.add(queueLabel);
        selectionPanel.add(queueScroll);
    }

    private void addComponents() {
        setUpSelectionPanel();
        add(selectionPanel);
    }

    public static void main(String[] args) {
        new GUI().setVisible(true);
    }
}

Answer 1

在添加listScroll后的这些行之后：

constraints.gridwidth = 2;
constraints.gridheight = 3;

您永远不会将它们重置为1，因此所有后续组件都将具有这些约束。只需添加：

constraints.gridwidth = 1;
constraints.gridheight = 1;

到你的filterBox约束中，它们将保留其余组件的方式，直到你需要时更改它们。