使用 GridBagLayout 设置组件

Question

我正在使用 GridBagLayout 来定位面板上的组件，但它无法正常工作。更改 x 和 y 值不会影响组件的位置有人请帮助解释我在这里犯了什么错误提前谢谢:)

import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;

import javax.swing.*;

public class LMS extends JFrame {
    JPanel mainPanel;
    JLabel RegNum, Name, FatherNam, MotherNam, DateBirth, BloodGrp, Email, Gender, RegDate, Desig, photo;
    JTextField RegNuumText, FatherNamText, MotherNamText, EmailText, DesigText;
    JList BloodGrpList;
    JSpinner DateSpi;

    // Constructor
    public LMS() {
        this.setTitle("Library Managment System");
        this.setVisible(true);
        this.setSize(700, 600);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setLocationRelativeTo(null);

        // this.setResizable(false);
        mainPanel = new JPanel();

        // GridBagLayout bag = new GridBagLayout();
        mainPanel.setLayout(new GridBagLayout());

        // Creating Labels
        RegNum = new JLabel("Registration Number");
        Name = new JLabel("Full Name");
        FatherNam = new JLabel("Father's Name");
        MotherNam = new JLabel("Mother's Name");
        DateBirth = new JLabel("Date Of Birth");
        BloodGrp = new JLabel("Blood Group");
        Email = new JLabel("Email");
        Gender = new JLabel("Gender");
        RegDate = new JLabel("Registration Date");
        Desig = new JLabel("Designation");
        photo = new JLabel("Photo");

        // creating Text Fields
        RegNuumText = new JTextField(30);
        FatherNamText = new JTextField();
        MotherNamText = new JTextField();
        EmailText = new JTextField();
        DesigText = new JTextField();

        // mainPanel.add(RegNum);
        addComp(mainPanel, RegNum, 0, 0, 2, 1, GridBagConstraints.EAST, GridBagConstraints.NONE);
        addComp(mainPanel, RegNuumText, 0, 1, 2, 1, GridBagConstraints.WEST, GridBagConstraints.NONE);
        this.add(mainPanel);
    }

    private void addComp(JPanel thePanel, JComponent comp, int xPos, 
            int yPos, int compWidth, int compHeight, int place, int stretch) {

        GridBagConstraints gridConstraints = new GridBagConstraints();

        gridConstraints.gridx = xPos;
        gridConstraints.gridy = yPos;
        gridConstraints.gridwidth = compWidth;
        gridConstraints.gridheight = compHeight;
        gridConstraints.weightx = 1;
        gridConstraints.weighty = 1;
        gridConstraints.insets = new Insets(5, 5, 5, 5);
        gridConstraints.anchor = place;
        gridConstraints.fill = stretch;

        thePanel.add(comp, gridConstraints);
    }

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

Answer 1

GridBagLayout 不是最简单的，你必须玩一点。也许这些行可以帮助您实现您想要的。他们会将标签放在左上角，将 Textfield 放在它后面。

请注意，有些面板被定义为占位符 - 它们将填充空白空间。

    addComp(mainPanel, RegNum, 0, 1, 1, 1, GridBagConstraints.WEST, GridBagConstraints.NONE);
    addComp(mainPanel, RegNuumText, 1, 1, 1, 1, GridBagConstraints.WEST, GridBagConstraints.NONE);
    addComp(mainPanel, new JPanel(), 2, 1, 1, 1, GridBagConstraints.WEST, GridBagConstraints.HORIZONTAL);
    addComp(mainPanel, new JPanel(), 0, 2, 1, 1, GridBagConstraints.WEST, GridBagConstraints.VERTICAL);

你还需要稍微改变你的辅助方法：

    gridConstraints.weightx = stretch == GridBagConstraints.NONE || stretch == GridBagConstraints.VERTICAL ? 0 : 1;
    gridConstraints.weighty = stretch == GridBagConstraints.NONE || stretch == GridBagConstraints.HORIZONTAL ? 0 : 1;

我认为这应该可以解决问题。也许你应该定义两个或三个辅助方法，这样你就不需要每次都设置所有参数。根据我的经验，您很少需要定义锚点，只有在某些时候您可能需要拉伸组件。大多数时候，对我来说，它只是将东西放入正确的袋子（x，y，有时：宽度，高度）。

编辑：也许将 setVisible() 放在定义的末尾而不是开头会有所帮助。