Java有组织的网格布局

Question

I'm making a program that asks for an integer from the user, it then should display a new window like this depending on how big the integer is.

This would be the layout if the user entered 2:

Enter test score:    JTextField over here
Enter test score:    JTextField over here
Reset             Submit

For some reason I can't make the grid layout in java have only 2 columns per row.

Here is my code:

public void createAverageGUI()
{
    averageFrame = new JFrame("Get All Test Scores");
    txtAllAverages = new JTextField[testCount];
    averageFrame.setLayout(new GridLayout(2, testCount));
    for (int i = 0; i < testCount; i++)
    {
        averageFrame.add(new JLabel("Enter test score: "));
        JTextField field = new JTextField(10);
        averageFrame.add(field);
        txtAllAverages[i] = field;
    }
    averageFrame.add(resetAverages);
    averageFrame.add(submitAverages);
    averageFrame.setSize(400, 600);
    averageFrame.setVisible(true);
}

Answer 1

What this GUI really needs is an entirely different layout. Here is how your planned GUI would look.

Here is how it should probably be laid out.

ExcellentGUI.java

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

class ExcellentGUI {

    private JTextField[] txtAllAverages;
    int testCount = 2;

    public void createAverageGUI()
    {
        txtAllAverages = new JTextField[testCount];

        JPanel inputControls = new JPanel(new BorderLayout(5,5));

        JPanel inputControlsLabels = new JPanel(new GridLayout(0,1,3,3));
        JPanel inputControlsFields = new JPanel(new GridLayout(0,1,3,3));
        inputControls.add(inputControlsLabels, BorderLayout.WEST);
        inputControls.add(inputControlsFields, BorderLayout.CENTER);
        for (int i = 0; i < testCount; i++)
        {
            inputControlsLabels.add(new JLabel("Test score: "));
            JTextField field = new JTextField(10);
            inputControlsFields.add(field);
            txtAllAverages[i] = field;
        }

        JPanel controls = new JPanel(new FlowLayout(FlowLayout.CENTER,5,2));

        controls.add(new JButton("Reset"));
        controls.add(new JButton("Submit"));

        JPanel gui = new JPanel(new BorderLayout(10,10));
        gui.setBorder(new TitledBorder("Averages"));
        gui.add(inputControls, BorderLayout.CENTER);
        gui.add(controls, BorderLayout.SOUTH);

        JFrame averageFrame = new JFrame("Get All Test Scores");
        averageFrame.setContentPane(gui);
        // let the components assume the natural size
        // averageFrame.setSize(400, 600);
        averageFrame.pack();
        averageFrame.setLocationByPlatform(true);
        averageFrame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        averageFrame.setVisible(true);
    }

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

Answer 2

You understand that this new GridLayout(2, testCount) means two rows and testCount columns, which isn't what I think you want. I strongly urge you to read the GridLayout API to see exactly how this and the other constructors work.

You can simplify things greatly by making your layout new GridLayout(0, 2); which means any number of rows and always 2 columns.