如何在彼此下方对齐多个元素？

Question

我很难将 Swing 元素流对齐到彼此下方。使用GridLayout 对我没有帮助，因为它将屏幕划分为大小相等的行。我需要在每一行放置一个组件，下一个组件应该在最后一个组件的最底部。

我的问题是，如果问题的选择多于一行，这种布局将它们挤压到行中，图片和问题“3+3？”之间存在巨大差距？

Answer 1

您可以为此使用GridBagLayout。这是非常容易使用。这是一个示例实现。

import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JRadioButton;

class MyFrame extends JFrame {

    public MyFrame() {
        JPanel panel = new JPanel(new GridBagLayout());

        JLabel image = new JLabel();
        image.setIcon(new ImageIcon(getClass().getResource("/image.png")));

        JLabel question = new JLabel("3 + 3 = ?");

        JRadioButton rb1 = new JRadioButton("5");
        JRadioButton rb2 = new JRadioButton("3");
        JRadioButton rb3 = new JRadioButton("6");
        JRadioButton rb4 = new JRadioButton("9");
        JRadioButton rb5 = new JRadioButton("23");

        GridBagConstraints c = new GridBagConstraints();

        c.gridx = 0;//set the x location of the grid for the next component
        c.gridy = 0;//set the y location of the grid for the next component
        panel.add(image,c);

        c.gridy = 1;//change the y location
        c.anchor=GridBagConstraints.WEST;//left align components after this point
        panel.add(question,c);

        c.gridy = 2;//change the y location
        panel.add(rb1,c);

        c.gridy = 3;//change the y location
        panel.add(rb2,c);

        c.gridy = 4;//change the y location
        panel.add(rb3,c);

        c.gridy = 5;//change the y location
        panel.add(rb4,c);

        c.gridy =6;//change the y location
        panel.add(rb5,c);

        this.getContentPane().add(panel);

        this.setDefaultCloseOperation(EXIT_ON_CLOSE);
        this.pack();
    }

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

}

参考：https://docs.oracle.com/javase/tutorial/uiswing/layout/gridbag.html

Answer 2

有许多可能的解决方案，但可能最有用的是GridBagLayout，虽然复杂，但非常灵活。

import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.JCheckBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Test {

    public static void main(String[] args) {
        new Test();
    }

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

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

    public class TestPane extends JPanel {

        public TestPane() {
            setLayout(new GridBagLayout());

            JLabel label = new JLabel("Cool");
            label.setFont(label.getFont().deriveFont(Font.BOLD, 48f));
            label.setOpaque(true);
            label.setBackground(Color.WHITE);

            GridBagConstraints gbc = new GridBagConstraints();
            gbc.gridwidth = GridBagConstraints.REMAINDER;

            add(label, gbc);
            add(new JLabel("3+5="), gbc);
            add(new JCheckBox("5"), gbc);
            add(new JCheckBox("3"), gbc);
            add(new JCheckBox("6"), gbc);
            add(new JCheckBox("9"), gbc);
            add(new JCheckBox("23"), gbc);
        }

    }

}

您甚至可以使用anchor 将组件移动到单元格内的不同位置...

gbc.anchor = GridBagConstraints.WEST;

显然，这些也可以应用于单个组件，因此每个组件都可以有自己的一组约束

查看How to Use GridBagLayout了解更多详情