Java 小GUI问题我无法解决。JTextFields_Java_User Interface_Jlabel_Jtextfield_Gridbaglayout

Java 小GUI问题我无法解决。JTextFields

java user-interface

Java 小GUI问题我无法解决。JTextFields,java,user-interface,jlabel,jtextfield,gridbaglayout,Java,User Interface,Jlabel,Jtextfield,Gridbaglayout,这个小错误我做不到。现在我的程序GUI如下所示：现在在“标记”列下有一个文本字段，用户可以输入他们的数据。如果我想在“权重”列的正下方插入一个文本字段，我还希望权重部分也有相同的内容但是，当我尝试输入一个文本字段时，当窗口很小时，两个文本字段都会像这样旋转：当窗口被放大时：如何设置标记和权重下的文本字段？代码：公共类Gradeanalysis实现ActionListener{ 已执行的公共无效操作（操作事件e）{ GridBagConstraints gbc=新的GridBag

这个小错误我做不到。现在我的程序GUI如下所示：

现在在“标记”列下有一个文本字段，用户可以输入他们的数据。如果我想在“权重”列的正下方插入一个文本字段，我还希望权重部分也有相同的内容

但是，当我尝试输入一个文本字段时，当窗口很小时，两个文本字段都会像这样旋转：

当窗口被放大时：

如何设置标记和权重下的文本字段？

代码：

公共类Gradeanalysis实现ActionListener{
已执行的公共无效操作（操作事件e）{
GridBagConstraints gbc=新的GridBagConstraints（）；
//添加JPanels.Panel以获取说明
JPanel面板=新的JPanel（）；
panel.setLayout（新的GridBagLayout（））；
//JLabel以获取说明。
JLabel标签=新的JLabel标签(“说明：键入您收到的成绩，以及它们在确定总体平均值时的权重。
按“计算”后，结果将显示您迄今为止的平均值。
您输入的每个成绩必须是非负数，输入的每个百分比/权重必须是正数：”；
gbc.fill=GridBagConstraints.HORIZONTAL；
gbc.gridwidth=2；
gbc.gridy=0；
面板。添加（标签，gbc）；
//JLabel1用于分配/等级/重量（百分比）
JLabel label1=新的JLabel（“Assingment\t\t\t\t Mark\t\t\t\t\tWeight”）；
gbc.fill=GridBagConstraints.HORIZONTAL；
gbc.gridx=0；
gbc.gridy=1；
gbc.anchor=gridbag.NORTH；
面板。添加（标签1，gbc）；
//JLabel编号用于侧面的辅助设备编号列表。
JLabel编号=新JLabel（“1”）；
gbc.gridx=0；
gbc.gridy=2；
gbc.anchor=gridbag.NORTH；
gbc.weighty=1；
面板。添加（编号，gbc）；
//标记的JTextfield
JTextField标记=新的JTextField（2）；
gbc.fill=GridBagConstraints.NONE；
gbc.gridy=2；
面板。添加（标记，gbc）；
//用于权重的JTextfield
JTextField权重=新的JTextField（2）；
gbc.gridx=2；
面板。添加（重量，gbc）；
//新帧集
JFrame frame=新JFrame（“坡度计算器--”）；
frame.setVisible（true）；
框架。设置尺寸（750700）；
frame.setDefaultCloseOperation（关闭时退出）；
框架。添加（面板）；
}

}

感谢阅读。

您可以为每个JTextField设置最小、预期和最大大小，如下所示：

package com.ggl.testing;

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

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;

public class GradeAnalysis implements Runnable {

    private static final Insets normalInsets = new Insets(10, 10, 0, 10);
    private static final Insets finalInsets = new Insets(10, 10, 10, 10);

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new GradeAnalysis());
    }

    @Override
    public void run() {
        JFrame frame = new JFrame("Grade Calculator");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(createMainPanel());
        frame.pack();
        frame.setVisible(true);
    }

    private JPanel createMainPanel() {
        GridBagConstraints gbc = new GridBagConstraints();

        // Adding the JPanels. Panel for instructions
        JPanel panel = new JPanel();
        panel.setLayout(new GridBagLayout());

        int gridy = 0;

        // JLabel for the Instructions.
        JTextArea instructionTextArea = new JTextArea(5, 30);
        instructionTextArea.setEditable(false);
        instructionTextArea.setLineWrap(true);
        instructionTextArea.setWrapStyleWord(true);
        instructionTextArea.setText(getInstructions());
        JScrollPane instructionScrollPane = new JScrollPane(instructionTextArea);
        addComponent(panel, instructionScrollPane, 0, gridy++, 3, 1,
                finalInsets, GridBagConstraints.CENTER,
                GridBagConstraints.HORIZONTAL);

        // JLabels for Assignment/Grade/Weight(Percent)
        JLabel label1 = new JLabel("Assignment");
        label1.setHorizontalAlignment(JLabel.CENTER);
        addComponent(panel, label1, 0, gridy, 1, 1, finalInsets,
                GridBagConstraints.CENTER, GridBagConstraints.HORIZONTAL);

        JLabel label2 = new JLabel("Mark");
        label2.setHorizontalAlignment(JLabel.CENTER);
        addComponent(panel, label2, 1, gridy, 1, 1, finalInsets,
                GridBagConstraints.CENTER, GridBagConstraints.HORIZONTAL);

        JLabel label3 = new JLabel("Weight");
        label3.setHorizontalAlignment(JLabel.CENTER);
        addComponent(panel, label3, 2, gridy++, 1, 1, finalInsets,
                GridBagConstraints.CENTER, GridBagConstraints.HORIZONTAL);

        // JLabel Numbers for the number list of assignments at the side.
        JLabel number = new JLabel("1");
        number.setHorizontalAlignment(JLabel.CENTER);
        addComponent(panel, number, 0, gridy, 1, 1, normalInsets,
                GridBagConstraints.CENTER, GridBagConstraints.HORIZONTAL);

        // JTextfield for Mark
        JTextField mark = new JTextField(20);
        mark.setHorizontalAlignment(JLabel.CENTER);
        addComponent(panel, mark, 1, gridy, 1, 1, normalInsets,
                GridBagConstraints.CENTER, GridBagConstraints.HORIZONTAL);

        // JTextfield for Weight
        JTextField weight = new JTextField(20);
        weight.setHorizontalAlignment(JLabel.CENTER);
        addComponent(panel, weight, 2, gridy++, 1, 1, normalInsets,
                GridBagConstraints.CENTER, GridBagConstraints.HORIZONTAL);

        return panel;
    }

    private String getInstructions() {
        return "Instructions: Type in the grades you’ve received, along with the weights "
                + "they’ll have in the determination of your overall average. After you "
                + "press ‘Calculate’, the results will show your average so far. Every "
                + "grade you enter must be a non-negative number, and every "
                + "percentage/weight you enter must be a positive number :)";
    }

    private void addComponent(Container container, Component component,
            int gridx, int gridy, int gridwidth, int gridheight, Insets insets,
            int anchor, int fill) {
        GridBagConstraints gbc = new GridBagConstraints(gridx, gridy,
                gridwidth, gridheight, 1.0D, 1.0D, anchor, fill, insets, 0, 0);
        container.add(component, gbc);
    }

}

其中MIN和MAX是一个维度对象，设置边界的输入是

int

，您可以为每个JTextField设置最小、预期和最大大小，如下所示：

package com.ggl.testing;

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

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;

public class GradeAnalysis implements Runnable {

    private static final Insets normalInsets = new Insets(10, 10, 0, 10);
    private static final Insets finalInsets = new Insets(10, 10, 10, 10);

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new GradeAnalysis());
    }

    @Override
    public void run() {
        JFrame frame = new JFrame("Grade Calculator");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(createMainPanel());
        frame.pack();
        frame.setVisible(true);
    }

    private JPanel createMainPanel() {
        GridBagConstraints gbc = new GridBagConstraints();

        // Adding the JPanels. Panel for instructions
        JPanel panel = new JPanel();
        panel.setLayout(new GridBagLayout());

        int gridy = 0;

        // JLabel for the Instructions.
        JTextArea instructionTextArea = new JTextArea(5, 30);
        instructionTextArea.setEditable(false);
        instructionTextArea.setLineWrap(true);
        instructionTextArea.setWrapStyleWord(true);
        instructionTextArea.setText(getInstructions());
        JScrollPane instructionScrollPane = new JScrollPane(instructionTextArea);
        addComponent(panel, instructionScrollPane, 0, gridy++, 3, 1,
                finalInsets, GridBagConstraints.CENTER,
                GridBagConstraints.HORIZONTAL);

        // JLabels for Assignment/Grade/Weight(Percent)
        JLabel label1 = new JLabel("Assignment");
        label1.setHorizontalAlignment(JLabel.CENTER);
        addComponent(panel, label1, 0, gridy, 1, 1, finalInsets,
                GridBagConstraints.CENTER, GridBagConstraints.HORIZONTAL);

        JLabel label2 = new JLabel("Mark");
        label2.setHorizontalAlignment(JLabel.CENTER);
        addComponent(panel, label2, 1, gridy, 1, 1, finalInsets,
                GridBagConstraints.CENTER, GridBagConstraints.HORIZONTAL);

        JLabel label3 = new JLabel("Weight");
        label3.setHorizontalAlignment(JLabel.CENTER);
        addComponent(panel, label3, 2, gridy++, 1, 1, finalInsets,
                GridBagConstraints.CENTER, GridBagConstraints.HORIZONTAL);

        // JLabel Numbers for the number list of assignments at the side.
        JLabel number = new JLabel("1");
        number.setHorizontalAlignment(JLabel.CENTER);
        addComponent(panel, number, 0, gridy, 1, 1, normalInsets,
                GridBagConstraints.CENTER, GridBagConstraints.HORIZONTAL);

        // JTextfield for Mark
        JTextField mark = new JTextField(20);
        mark.setHorizontalAlignment(JLabel.CENTER);
        addComponent(panel, mark, 1, gridy, 1, 1, normalInsets,
                GridBagConstraints.CENTER, GridBagConstraints.HORIZONTAL);

        // JTextfield for Weight
        JTextField weight = new JTextField(20);
        weight.setHorizontalAlignment(JLabel.CENTER);
        addComponent(panel, weight, 2, gridy++, 1, 1, normalInsets,
                GridBagConstraints.CENTER, GridBagConstraints.HORIZONTAL);

        return panel;
    }

    private String getInstructions() {
        return "Instructions: Type in the grades you’ve received, along with the weights "
                + "they’ll have in the determination of your overall average. After you "
                + "press ‘Calculate’, the results will show your average so far. Every "
                + "grade you enter must be a non-negative number, and every "
                + "percentage/weight you enter must be a positive number :)";
    }

    private void addComponent(Container container, Component component,
            int gridx, int gridy, int gridwidth, int gridheight, Insets insets,
            int anchor, int fill) {
        GridBagConstraints gbc = new GridBagConstraints(gridx, gridy,
                gridwidth, gridheight, 1.0D, 1.0D, anchor, fill, insets, 0, 0);
        container.add(component, gbc);
    }

}

其中MIN和MAX是一个维度对象，设置边界的输入是

int

，您可以为每个JTextField设置最小、预期和最大大小，如下所示：

package com.ggl.testing;

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

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;

public class GradeAnalysis implements Runnable {

    private static final Insets normalInsets = new Insets(10, 10, 0, 10);
    private static final Insets finalInsets = new Insets(10, 10, 10, 10);

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new GradeAnalysis());
    }

    @Override
    public void run() {
        JFrame frame = new JFrame("Grade Calculator");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(createMainPanel());
        frame.pack();
        frame.setVisible(true);
    }

    private JPanel createMainPanel() {
        GridBagConstraints gbc = new GridBagConstraints();

        // Adding the JPanels. Panel for instructions
        JPanel panel = new JPanel();
        panel.setLayout(new GridBagLayout());

        int gridy = 0;

        // JLabel for the Instructions.
        JTextArea instructionTextArea = new JTextArea(5, 30);
        instructionTextArea.setEditable(false);
        instructionTextArea.setLineWrap(true);
        instructionTextArea.setWrapStyleWord(true);
        instructionTextArea.setText(getInstructions());
        JScrollPane instructionScrollPane = new JScrollPane(instructionTextArea);
        addComponent(panel, instructionScrollPane, 0, gridy++, 3, 1,
                finalInsets, GridBagConstraints.CENTER,
                GridBagConstraints.HORIZONTAL);

        // JLabels for Assignment/Grade/Weight(Percent)
        JLabel label1 = new JLabel("Assignment");
        label1.setHorizontalAlignment(JLabel.CENTER);
        addComponent(panel, label1, 0, gridy, 1, 1, finalInsets,
                GridBagConstraints.CENTER, GridBagConstraints.HORIZONTAL);

        JLabel label2 = new JLabel("Mark");
        label2.setHorizontalAlignment(JLabel.CENTER);
        addComponent(panel, label2, 1, gridy, 1, 1, finalInsets,
                GridBagConstraints.CENTER, GridBagConstraints.HORIZONTAL);

        JLabel label3 = new JLabel("Weight");
        label3.setHorizontalAlignment(JLabel.CENTER);
        addComponent(panel, label3, 2, gridy++, 1, 1, finalInsets,
                GridBagConstraints.CENTER, GridBagConstraints.HORIZONTAL);

        // JLabel Numbers for the number list of assignments at the side.
        JLabel number = new JLabel("1");
        number.setHorizontalAlignment(JLabel.CENTER);
        addComponent(panel, number, 0, gridy, 1, 1, normalInsets,
                GridBagConstraints.CENTER, GridBagConstraints.HORIZONTAL);

        // JTextfield for Mark
        JTextField mark = new JTextField(20);
        mark.setHorizontalAlignment(JLabel.CENTER);
        addComponent(panel, mark, 1, gridy, 1, 1, normalInsets,
                GridBagConstraints.CENTER, GridBagConstraints.HORIZONTAL);

        // JTextfield for Weight
        JTextField weight = new JTextField(20);
        weight.setHorizontalAlignment(JLabel.CENTER);
        addComponent(panel, weight, 2, gridy++, 1, 1, normalInsets,
                GridBagConstraints.CENTER, GridBagConstraints.HORIZONTAL);

        return panel;
    }

    private String getInstructions() {
        return "Instructions: Type in the grades you’ve received, along with the weights "
                + "they’ll have in the determination of your overall average. After you "
                + "press ‘Calculate’, the results will show your average so far. Every "
                + "grade you enter must be a non-negative number, and every "
                + "percentage/weight you enter must be a positive number :)";
    }

    private void addComponent(Container container, Component component,
            int gridx, int gridy, int gridwidth, int gridheight, Insets insets,
            int anchor, int fill) {
        GridBagConstraints gbc = new GridBagConstraints(gridx, gridy,
                gridwidth, gridheight, 1.0D, 1.0D, anchor, fill, insets, 0, 0);
        container.add(component, gbc);
    }

}

其中MIN和MAX是一个维度对象，设置边界的输入是

int

，您可以为每个JTextField设置最小、预期和最大大小，如下所示：

package com.ggl.testing;

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

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;

public class GradeAnalysis implements Runnable {

    private static final Insets normalInsets = new Insets(10, 10, 0, 10);
    private static final Insets finalInsets = new Insets(10, 10, 10, 10);

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new GradeAnalysis());
    }

    @Override
    public void run() {
        JFrame frame = new JFrame("Grade Calculator");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(createMainPanel());
        frame.pack();
        frame.setVisible(true);
    }

    private JPanel createMainPanel() {
        GridBagConstraints gbc = new GridBagConstraints();

        // Adding the JPanels. Panel for instructions
        JPanel panel = new JPanel();
        panel.setLayout(new GridBagLayout());

        int gridy = 0;

        // JLabel for the Instructions.
        JTextArea instructionTextArea = new JTextArea(5, 30);
        instructionTextArea.setEditable(false);
        instructionTextArea.setLineWrap(true);
        instructionTextArea.setWrapStyleWord(true);
        instructionTextArea.setText(getInstructions());
        JScrollPane instructionScrollPane = new JScrollPane(instructionTextArea);
        addComponent(panel, instructionScrollPane, 0, gridy++, 3, 1,
                finalInsets, GridBagConstraints.CENTER,
                GridBagConstraints.HORIZONTAL);

        // JLabels for Assignment/Grade/Weight(Percent)
        JLabel label1 = new JLabel("Assignment");
        label1.setHorizontalAlignment(JLabel.CENTER);
        addComponent(panel, label1, 0, gridy, 1, 1, finalInsets,
                GridBagConstraints.CENTER, GridBagConstraints.HORIZONTAL);

        JLabel label2 = new JLabel("Mark");
        label2.setHorizontalAlignment(JLabel.CENTER);
        addComponent(panel, label2, 1, gridy, 1, 1, finalInsets,
                GridBagConstraints.CENTER, GridBagConstraints.HORIZONTAL);

        JLabel label3 = new JLabel("Weight");
        label3.setHorizontalAlignment(JLabel.CENTER);
        addComponent(panel, label3, 2, gridy++, 1, 1, finalInsets,
                GridBagConstraints.CENTER, GridBagConstraints.HORIZONTAL);

        // JLabel Numbers for the number list of assignments at the side.
        JLabel number = new JLabel("1");
        number.setHorizontalAlignment(JLabel.CENTER);
        addComponent(panel, number, 0, gridy, 1, 1, normalInsets,
                GridBagConstraints.CENTER, GridBagConstraints.HORIZONTAL);

        // JTextfield for Mark
        JTextField mark = new JTextField(20);
        mark.setHorizontalAlignment(JLabel.CENTER);
        addComponent(panel, mark, 1, gridy, 1, 1, normalInsets,
                GridBagConstraints.CENTER, GridBagConstraints.HORIZONTAL);

        // JTextfield for Weight
        JTextField weight = new JTextField(20);
        weight.setHorizontalAlignment(JLabel.CENTER);
        addComponent(panel, weight, 2, gridy++, 1, 1, normalInsets,
                GridBagConstraints.CENTER, GridBagConstraints.HORIZONTAL);

        return panel;
    }

    private String getInstructions() {
        return "Instructions: Type in the grades you’ve received, along with the weights "
                + "they’ll have in the determination of your overall average. After you "
                + "press ‘Calculate’, the results will show your average so far. Every "
                + "grade you enter must be a non-negative number, and every "
                + "percentage/weight you enter must be a positive number :)";
    }

    private void addComponent(Container container, Component component,
            int gridx, int gridy, int gridwidth, int gridheight, Insets insets,
            int anchor, int fill) {
        GridBagConstraints gbc = new GridBagConstraints(gridx, gridy,
                gridwidth, gridheight, 1.0D, 1.0D, anchor, fill, insets, 0, 0);
        container.add(component, gbc);
    }

}

其中MIN和MAX是一个维度对象，设置边界的输入是

int

这是我创建的GUI

我不知道您的主方法在哪里，但是您必须始终通过调用SwingUtilities invokeLater方法启动Swing应用程序。invokeLater方法将Swing组件的创建和执行置于

当我使用GridBagLayout时，我使用我创建的addComponent方法为每个Swing组件创建一个唯一的GridBagConstraints

JFrame方法的顺序非常重要。记住本例中JFrame方法的顺序

我把指令放在JTextArea中。这样，指令文本根据JTextArea的大小进行分割。不需要用HTML硬编码换行符

这是密码

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.util.List;

import javax.swing.*;

@SuppressWarnings("serial")
public class GradeAnalysis2 extends JPanel {
   private static final int PREF_H = 400;
   private static final String DISPLAY_TEXT = "Instructions: "
         + "Type in the grades you’ve received, along with the "
         + "weights they’ll have in the determination of your "
         + "overall average.\n"
         + "After you press ‘Calculate’, the results will show "
         + "your average so far.\n"
         + "Every grade you enter must be a non-negative number, "
         + "and every percentage/weight you enter must be a "
         + "positive number :)";
   private JTextArea displayArea = new JTextArea(5, 50);
   private GradeTablePanel gradeTablePanel = new GradeTablePanel();

   public GradeAnalysis2() {
      displayArea.setText(DISPLAY_TEXT);
      displayArea.setWrapStyleWord(true);
      displayArea.setLineWrap(true);
      displayArea.setEditable(false);
      displayArea.setFocusable(false);
      displayArea.setBorder(null);
      displayArea.setBackground(null);

      JPanel centerPanel = new JPanel(new BorderLayout());
      centerPanel.add(gradeTablePanel, BorderLayout.PAGE_START);
      centerPanel.add(Box.createGlue(), BorderLayout.CENTER);
      JScrollPane scrollPane = new JScrollPane(centerPanel);

      JPanel btnPanel = new JPanel();
      btnPanel.add(new JButton(new AddAssignmentAction("Add")));

      setLayout(new BorderLayout());
      add(displayArea, BorderLayout.PAGE_START);
      add(scrollPane, BorderLayout.CENTER);
      add(btnPanel, BorderLayout.PAGE_END);
   }

   @Override
   public Dimension getPreferredSize() {
      Dimension sz = super.getPreferredSize();
      if (isPreferredSizeSet()) {
         return sz;
      }
      int height = Math.max(sz.height, PREF_H);
      return new Dimension(sz.width, height);
   }

   private class AddAssignmentAction extends AbstractAction {
      public AddAssignmentAction(String name) {
         super(name);
         int mnenomic = (int) name.charAt(0);
         putValue(MNEMONIC_KEY, mnenomic);
      }

      public void actionPerformed(ActionEvent e) {
         gradeTablePanel.addAssignment();
         gradeTablePanel.revalidate();
         gradeTablePanel.repaint();
      };
   }

   private class GradeTablePanel extends JPanel {
      private int count = 0;

      // parallel collections -- a bad kludge. 
      // a table model would make this much cleaner
      private List<JTextField> marks;
      private List<JTextField> weights;

      public GradeTablePanel() {
         setLayout(new GridBagLayout());
         JLabel assgmntLbl = new JLabel(Assignment.ASSIGNMENT, SwingConstants.CENTER);
         assgmntLbl.setFont(assgmntLbl.getFont().deriveFont(Font.BOLD));
         JLabel markLbl = new JLabel(Assignment.MARK, SwingConstants.CENTER);
         markLbl.setFont(markLbl.getFont().deriveFont(Font.BOLD));
         JLabel weightLbl = new JLabel(Assignment.WEIGHT, SwingConstants.CENTER);
         weightLbl.setFont(weightLbl.getFont().deriveFont(Font.BOLD));

         add(assgmntLbl, createGbc(0, 0));
         add(markLbl, createGbc(1, 0));
         add(weightLbl, createGbc(2, 0));
      }

      private GridBagConstraints createGbc(int x, int y) {
         GridBagConstraints gbc = new GridBagConstraints();
         gbc.gridx = x;
         gbc.gridy = y;
         gbc.gridwidth = 1;
         gbc.gridheight = 1;
         gbc.fill = GridBagConstraints.VERTICAL;
         gbc.weightx = 1.0;
         gbc.weighty = 1.0;
         gbc.anchor = GridBagConstraints.CENTER;
         return gbc;
      }

      public void addAssignment() {
         count++;
         JLabel countLabel = new JLabel(String.valueOf(count));
         JTextField markField = new JTextField(2);
         JTextField weightField = new JTextField(2);

         add(countLabel, createGbc(0, count));
         add(markField, createGbc(1, count));
         add(weightField, createGbc(2, count));
      }

   }

   private static void createAndShowGui() {
      JFrame frame = new JFrame("GradeAnalysis2");
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.getContentPane().add(new GradeAnalysis2());
      frame.pack();
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);
   }

   public static void main(String[] args) {
      SwingUtilities.invokeLater(new Runnable() {
         public void run() {
            createAndShowGui();
         }
      });
   }
}


class Assignment {
   public static final String ASSIGNMENT = "Assignment";
   public static final String MARK = "Mark";
   public static final String WEIGHT = "Weight";
   private String assignment;
   private int mark;
   private double weight;
   public Assignment(String assignment, int mark, double weight) {
      this.assignment = assignment;
      this.mark = mark;
      this.weight = weight;
   }
   public String getAssignment() {
      return assignment;
   }
   public void setAssignment(String assignment) {
      this.assignment = assignment;
   }
   public int getMark() {
      return mark;
   }
   public void setMark(int mark) {
      this.mark = mark;
   }
   public double getWeight() {
      return weight;
   }
   public void setWeight(double weight) {
      this.weight = weight;
   }


}

这是我创建的GUI

我不知道您的主方法在哪里，但是您必须始终通过调用SwingUtilities invokeLater方法启动Swing应用程序。invokeLater方法将Swing组件的创建和执行置于

当我使用GridBagLayout时，我使用我创建的addComponent方法为每个Swing组件创建一个唯一的GridBagConstraints

JFrame方法的顺序非常重要。记住本例中JFrame方法的顺序

我把指令放在JTextArea中。这样，指令文本根据JTextArea的大小进行分割。不需要用HTML硬编码换行符

这是密码

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.util.List;

import javax.swing.*;

@SuppressWarnings("serial")
public class GradeAnalysis2 extends JPanel {
   private static final int PREF_H = 400;
   private static final String DISPLAY_TEXT = "Instructions: "
         + "Type in the grades you’ve received, along with the "
         + "weights they’ll have in the determination of your "
         + "overall average.\n"
         + "After you press ‘Calculate’, the results will show "
         + "your average so far.\n"
         + "Every grade you enter must be a non-negative number, "
         + "and every percentage/weight you enter must be a "
         + "positive number :)";
   private JTextArea displayArea = new JTextArea(5, 50);
   private GradeTablePanel gradeTablePanel = new GradeTablePanel();

   public GradeAnalysis2() {
      displayArea.setText(DISPLAY_TEXT);
      displayArea.setWrapStyleWord(true);
      displayArea.setLineWrap(true);
      displayArea.setEditable(false);
      displayArea.setFocusable(false);
      displayArea.setBorder(null);
      displayArea.setBackground(null);

      JPanel centerPanel = new JPanel(new BorderLayout());
      centerPanel.add(gradeTablePanel, BorderLayout.PAGE_START);
      centerPanel.add(Box.createGlue(), BorderLayout.CENTER);
      JScrollPane scrollPane = new JScrollPane(centerPanel);

      JPanel btnPanel = new JPanel();
      btnPanel.add(new JButton(new AddAssignmentAction("Add")));

      setLayout(new BorderLayout());
      add(displayArea, BorderLayout.PAGE_START);
      add(scrollPane, BorderLayout.CENTER);
      add(btnPanel, BorderLayout.PAGE_END);
   }

   @Override
   public Dimension getPreferredSize() {
      Dimension sz = super.getPreferredSize();
      if (isPreferredSizeSet()) {
         return sz;
      }
      int height = Math.max(sz.height, PREF_H);
      return new Dimension(sz.width, height);
   }

   private class AddAssignmentAction extends AbstractAction {
      public AddAssignmentAction(String name) {
         super(name);
         int mnenomic = (int) name.charAt(0);
         putValue(MNEMONIC_KEY, mnenomic);
      }

      public void actionPerformed(ActionEvent e) {
         gradeTablePanel.addAssignment();
         gradeTablePanel.revalidate();
         gradeTablePanel.repaint();
      };
   }

   private class GradeTablePanel extends JPanel {
      private int count = 0;

      // parallel collections -- a bad kludge. 
      // a table model would make this much cleaner
      private List<JTextField> marks;
      private List<JTextField> weights;

      public GradeTablePanel() {
         setLayout(new GridBagLayout());
         JLabel assgmntLbl = new JLabel(Assignment.ASSIGNMENT, SwingConstants.CENTER);
         assgmntLbl.setFont(assgmntLbl.getFont().deriveFont(Font.BOLD));
         JLabel markLbl = new JLabel(Assignment.MARK, SwingConstants.CENTER);
         markLbl.setFont(markLbl.getFont().deriveFont(Font.BOLD));
         JLabel weightLbl = new JLabel(Assignment.WEIGHT, SwingConstants.CENTER);
         weightLbl.setFont(weightLbl.getFont().deriveFont(Font.BOLD));

         add(assgmntLbl, createGbc(0, 0));
         add(markLbl, createGbc(1, 0));
         add(weightLbl, createGbc(2, 0));
      }

      private GridBagConstraints createGbc(int x, int y) {
         GridBagConstraints gbc = new GridBagConstraints();
         gbc.gridx = x;
         gbc.gridy = y;
         gbc.gridwidth = 1;
         gbc.gridheight = 1;
         gbc.fill = GridBagConstraints.VERTICAL;
         gbc.weightx = 1.0;
         gbc.weighty = 1.0;
         gbc.anchor = GridBagConstraints.CENTER;
         return gbc;
      }

      public void addAssignment() {
         count++;
         JLabel countLabel = new JLabel(String.valueOf(count));
         JTextField markField = new JTextField(2);
         JTextField weightField = new JTextField(2);

         add(countLabel, createGbc(0, count));
         add(markField, createGbc(1, count));
         add(weightField, createGbc(2, count));
      }

   }

   private static void createAndShowGui() {
      JFrame frame = new JFrame("GradeAnalysis2");
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.getContentPane().add(new GradeAnalysis2());
      frame.pack();
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);
   }

   public static void main(String[] args) {
      SwingUtilities.invokeLater(new Runnable() {
         public void run() {
            createAndShowGui();
         }
      });
   }
}


class Assignment {
   public static final String ASSIGNMENT = "Assignment";
   public static final String MARK = "Mark";
   public static final String WEIGHT = "Weight";
   private String assignment;
   private int mark;
   private double weight;
   public Assignment(String assignment, int mark, double weight) {
      this.assignment = assignment;
      this.mark = mark;
      this.weight = weight;
   }
   public String getAssignment() {
      return assignment;
   }
   public void setAssignment(String assignment) {
      this.assignment = assignment;
   }
   public int getMark() {
      return mark;
   }
   public void setMark(int mark) {
      this.mark = mark;
   }
   public double getWeight() {
      return weight;
   }
   public void setWeight(double weight) {
      this.weight = weight;
   }


}

这是我创建的GUI

我不知道您的主方法在哪里，但是您必须始终通过调用SwingUtilities invokeLater方法启动Swing应用程序。invokeLater方法将Swing组件的创建和执行置于

当我使用GridBagLayout时，我使用我创建的addComponent方法为每个Swing组件创建一个唯一的GridBagConstraints

JFrame方法的顺序非常重要。记住本例中JFrame方法的顺序

我把指令放在JTextArea中。这样，指令文本根据JTextArea的大小进行分割。不需要用HTML硬编码换行符

这是密码

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.util.List;

import javax.swing.*;

@SuppressWarnings("serial")
public class GradeAnalysis2 extends JPanel {
   private static final int PREF_H = 400;
   private static final String DISPLAY_TEXT = "Instructions: "
         + "Type in the grades you’ve received, along with the "
         + "weights they’ll have in the determination of your "
         + "overall average.\n"
         + "After you press ‘Calculate’, the results will show "
         + "your average so far.\n"
         + "Every grade you enter must be a non-negative number, "
         + "and every percentage/weight you enter must be a "
         + "positive number :)";
   private JTextArea displayArea = new JTextArea(5, 50);
   private GradeTablePanel gradeTablePanel = new GradeTablePanel();

   public GradeAnalysis2() {
      displayArea.setText(DISPLAY_TEXT);
      displayArea.setWrapStyleWord(true);
      displayArea.setLineWrap(true);
      displayArea.setEditable(false);
      displayArea.setFocusable(false);
      displayArea.setBorder(null);
      displayArea.setBackground(null);

      JPanel centerPanel = new JPanel(new BorderLayout());
      centerPanel.add(gradeTablePanel, BorderLayout.PAGE_START);
      centerPanel.add(Box.createGlue(), BorderLayout.CENTER);
      JScrollPane scrollPane = new JScrollPane(centerPanel);

      JPanel btnPanel = new JPanel();
      btnPanel.add(new JButton(new AddAssignmentAction("Add")));

      setLayout(new BorderLayout());
      add(displayArea, BorderLayout.PAGE_START);
      add(scrollPane, BorderLayout.CENTER);
      add(btnPanel, BorderLayout.PAGE_END);
   }

   @Override
   public Dimension getPreferredSize() {
      Dimension sz = super.getPreferredSize();
      if (isPreferredSizeSet()) {
         return sz;
      }
      int height = Math.max(sz.height, PREF_H);
      return new Dimension(sz.width, height);
   }

   private class AddAssignmentAction extends AbstractAction {
      public AddAssignmentAction(String name) {
         super(name);
         int mnenomic = (int) name.charAt(0);
         putValue(MNEMONIC_KEY, mnenomic);
      }

      public void actionPerformed(ActionEvent e) {
         gradeTablePanel.addAssignment();
         gradeTablePanel.revalidate();
         gradeTablePanel.repaint();
      };
   }

   private class GradeTablePanel extends JPanel {
      private int count = 0;

      // parallel collections -- a bad kludge. 
      // a table model would make this much cleaner
      private List<JTextField> marks;
      private List<JTextField> weights;

      public GradeTablePanel() {
         setLayout(new GridBagLayout());
         JLabel assgmntLbl = new JLabel(Assignment.ASSIGNMENT, SwingConstants.CENTER);
         assgmntLbl.setFont(assgmntLbl.getFont().deriveFont(Font.BOLD));
         JLabel markLbl = new JLabel(Assignment.MARK, SwingConstants.CENTER);
         markLbl.setFont(markLbl.getFont().deriveFont(Font.BOLD));
         JLabel weightLbl = new JLabel(Assignment.WEIGHT, SwingConstants.CENTER);
         weightLbl.setFont(weightLbl.getFont().deriveFont(Font.BOLD));

         add(assgmntLbl, createGbc(0, 0));
         add(markLbl, createGbc(1, 0));
         add(weightLbl, createGbc(2, 0));
      }

      private GridBagConstraints createGbc(int x, int y) {
         GridBagConstraints gbc = new GridBagConstraints();
         gbc.gridx = x;
         gbc.gridy = y;
         gbc.gridwidth = 1;
         gbc.gridheight = 1;
         gbc.fill = GridBagConstraints.VERTICAL;
         gbc.weightx = 1.0;
         gbc.weighty = 1.0;
         gbc.anchor = GridBagConstraints.CENTER;
         return gbc;
      }

      public void addAssignment() {
         count++;
         JLabel countLabel = new JLabel(String.valueOf(count));
         JTextField markField = new JTextField(2);
         JTextField weightField = new JTextField(2);

         add(countLabel, createGbc(0, count));
         add(markField, createGbc(1, count));
         add(weightField, createGbc(2, count));
      }

   }

   private static void createAndShowGui() {
      JFrame frame = new JFrame("GradeAnalysis2");
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.getContentPane().add(new GradeAnalysis2());
      frame.pack();
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);
   }

   public static void main(String[] args) {
      SwingUtilities.invokeLater(new Runnable() {
         public void run() {
            createAndShowGui();
         }
      });
   }
}


class Assignment {
   public static final String ASSIGNMENT = "Assignment";
   public static final String MARK = "Mark";
   public static final String WEIGHT = "Weight";
   private String assignment;
   private int mark;
   private double weight;
   public Assignment(String assignment, int mark, double weight) {
      this.assignment = assignment;
      this.mark = mark;
      this.weight = weight;
   }
   public String getAssignment() {
      return assignment;
   }
   public void setAssignment(String assignment) {
      this.assignment = assignment;
   }
   public int getMark() {
      return mark;
   }
   public void setMark(int mark) {
      this.mark = mark;
   }
   public double getWeight() {
      return weight;
   }
   public void setWeight(double weight) {
      this.weight = weight;
   }


}

这是我创建的GUI

我不知道您的主方法在哪里，但是您必须始终通过调用SwingUtilities invokeLater方法启动Swing应用程序