Question

有一个完整的编译代码，按照我的书中的示例，现在我迷失了尝试更改JPanel的设置，以显示两列测试分数及其重量的文本输入...显示的是测试和重量叠在一起......

我的代码如下：

    import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class WeightedAverage extends JFrame
{         // Defines all variables
    private JLabel Test1, Test2,
           Test3, Test4, Weight1, Weight2, Weight3, Weight4, ansa;

    private JTextField testa, testb, testc, testd, weighta, weightb, weightc, weightd, ans;

    private JButton calculateB, exitB;

    private CalculateButtonHandler cbHandler;

    private ExitButtonHandler ebHandler;
          // Sets programs dimensions
    private static final int WIDTH = 500;
    private static final int HEIGHT = 600;

    public WeightedAverage()
    {
          // Create labels of text fields
     Test1 = new JLabel("First Test Score: ",
                            SwingConstants.RIGHT);
     Weight1 = new JLabel("And It's Weight: ",
                            SwingConstants.RIGHT);

     Test2 = new JLabel("Second Test Score: ",
                       SwingConstants.RIGHT);
     Weight2 = new JLabel("And It's Weight: ",
                       SwingConstants.RIGHT);

     Test3 = new JLabel("Third Test Score: ",
                        SwingConstants.RIGHT);
     Weight3 = new JLabel("And It's Weight: ",
                        SwingConstants.RIGHT);

     Test4 = new JLabel("Fourth Test Score: ",
                        SwingConstants.RIGHT);
     Weight4 = new JLabel("And It's Weight: ",
                        SwingConstants.RIGHT);


      ansa = new JLabel("You may not want to see this: ",
                        SwingConstants.RIGHT);


            //Create input text fields
     testa = new JTextField(10);
     weighta = new JTextField(10);
     testb = new JTextField(10);
     weightb = new JTextField(10);
     testc = new JTextField(10);
     weightc = new JTextField(10);
     testd = new JTextField(10);
     weightd = new JTextField(10);




            //create Calculate Button
     calculateB = new JButton("Crack that whip!");
     cbHandler = new CalculateButtonHandler();
     calculateB.addActionListener(cbHandler);

            //Create Exit Button
     exitB = new JButton("Begone!");
     ebHandler = new ExitButtonHandler();
     exitB.addActionListener(ebHandler);

            //Creat Answer Field
     ans = new JTextField(10);

            //Set the title of the window
     setTitle("Yes master");

            //Get the container
     Container pane = getContentPane();

            //Set the layout
     pane.setLayout(new GridLayout(10,4));

            //Place all items created
     pane.add(Test1);
     pane.add(testa);
     pane.add(Weight1);
     pane.add(weighta);

     pane.add(Test2);
     pane.add(testb);
     pane.add(Weight2);
     pane.add(weightb);

     pane.add(Test3);
     pane.add(testc);
     pane.add(Weight3);
     pane.add(weightc);

     pane.add(Test4);
     pane.add(testd);
     pane.add(Weight4);
     pane.add(weightd);

     pane.add(calculateB);
     pane.add(exitB);
     pane.add(ansa);
     pane.add(ans);



          //set the size of the window and display it
     setSize(WIDTH,HEIGHT);
     setVisible(true);
     setDefaultCloseOperation(EXIT_ON_CLOSE);
    }

    private class CalculateButtonHandler implements ActionListener
    {
     public void actionPerformed(ActionEvent e)
     {
         double t1, t2, t3, t4, w1, w2, w3, w4, avg1, avg2, avg3, avg4, favg;

         t1 = Double.parseDouble(testa.getText());
         w1 = Double.parseDouble(weighta.getText());
         t2 = Double.parseDouble(testb.getText());
         w2 = Double.parseDouble(weightb.getText());
         t3 = Double.parseDouble(testc.getText());
         w3 = Double.parseDouble(weightc.getText());
         t4 = Double.parseDouble(testd.getText());
         w4 = Double.parseDouble(weightd.getText());


         // Calculations Required to output weighted average
         avg1 = t1 * w1;
         avg2 = t2 * w2;
         avg3 = t3 * w3;
         avg4 = t4 * w4;
         favg = avg1 + avg2 + avg3 + avg4;
         // Outputs the weighted Average
         ans.setText("" + favg);

     }
    }

    private class ExitButtonHandler implements ActionListener
    {
         // Exits the program
     public void actionPerformed(ActionEvent e)
     {
      System.exit(0);
     }
    }

    public static void main(String[] args)
    {
     WeightedAverage weight = new WeightedAverage();
    }
}

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Answer 1

你想要5行而不是10行。new GridLayout(5, 4)会起作用，但更简单的是对行使用0 - 这意味着根据需要添加新行：

pane.setLayout(new GridLayout(0, 4));

与问题无关，但不建议指定窗口大小。而是在显示窗口之前使用pack()。这导致窗口大小自动确定，适合内容窗格的首选大小。

...
pack();
setVisible(true);

最后，swing是单线程的，访问和创建swing组件应该只在event dispatch thread中完成，所以你应该创建如下的GUI：

public static void main(String[] args)
{
    SwingUtilities.invokeLater(new Runnable() {
        @Override
        public void run() {
            WeightedAverage weight = new WeightedAverage(); 
        }
    });
}

Java GUI完全丢失了

1 个答案: