Question

我一直试图让我的JApplet以有序的方式显示计算器applet所需的所有按钮，但我似乎无法让它们全部具有相同的尺寸并且在彼此之下显示。我应该使用不同的不同布局还是改变整个设计？提前谢谢。

import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.BoxLayout;
import javax.swing.JApplet;
import javax.swing.JButton;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class MyCalc extends JApplet implements ActionListener{

/**
 * 
 */
protected static final long serialVersionUID = 3169756252830354073L;

private JMenuBar menuBar = new JMenuBar();
private JMenu edit = new JMenu("Edit");
private JMenu view = new JMenu("View");
private JMenu help = new JMenu("Help");

//Instantiated all JPanels used in this Applet
private JPanel[] rows = {new JPanel(), new JPanel(), new JPanel(), 
        new JPanel(), new JPanel(), new JPanel(), new JPanel()};

JTextField calc = new JTextField(1);

private JButton[] buttons = {new JButton("Backspace"), new JButton("CE"), new JButton("C"), 
        new JButton("MC"), new JButton("7"), new JButton("8"), new JButton("9"), 
        new JButton("/"), new JButton("sqrt"), new JButton("MR"), new JButton("4"), 
        new JButton("5"), new JButton("6"), new JButton("*"), new JButton("%"), 
        new JButton("MS"), new JButton("1"), new JButton("2"), new JButton("3"), 
        new JButton("-"), new JButton("1/x"), new JButton("M+"), new JButton("0"), 
        new JButton("+/-"), new JButton("."), new JButton("+"), new JButton("=")};

public void actionPerformed(ActionEvent e) {

    if(e.getSource() == buttons[0])
    {

    }

}

public void init()
{
    setName("Calculator Applet");
    menuBar.add(edit);
    menuBar.add(view);
    menuBar.add(help);
    setJMenuBar(menuBar);

    rows[0].setLayout(new BoxLayout(rows[0], BoxLayout.Y_AXIS));
    getContentPane();
    add(rows[0]);
    setSize(300, 200);

    calc.setText("0.");
    calc.setHorizontalAlignment(JTextField.RIGHT);

    for(int i = 0; i < 3; i++)
    {
        rows[2].add(buttons[i]);
    }

    for(int i = 3; i < 9; i++)
    {
        rows[3].add(buttons[i]);
    }

    for(int i = 9; i < 15; i++)
    {
        rows[4].add(buttons[i]);
    }

    for(int i = 15; i < 21; i++)
    {
        rows[5].add(buttons[i]);
    }

    for(int i = 21; i < 26; i++)
    {
        rows[6].add(buttons[i]);
    }

    rows[1].add(calc);
    rows[1].setLayout(new GridLayout());
    rows[2].setLayout(new GridLayout());
    rows[0].add(rows[1]);
    rows[0].add(rows[2]);

    for(int i = 3; i < 7; i++)
    {
        rows[0].add(rows[i]);
        rows[i].setLayout(new FlowLayout(FlowLayout.CENTER));
    }

}

Answer 1

＆＃34;但我似乎无法将它们全部放在相同的尺寸下并显示在彼此之下。＆＃34;

通常这会尖叫GridLayout。而不是使用两个BoxLayout（一个垂直和一个水平）只需使用GridLayout(4, 6)（对于数字按钮）。请记住，按钮的大小将是最大按钮的大小（即sqrt）。

另外，我建议远离将您的面板保持在阵列中，就像您正在做的那样。很难跟踪你想要添加所有内容的流程。为您的面板（以及所有组件）提供有意义的自我记录名称。

有关布局管理器的一般知识，请查看Laying out Component Within a Container

我重构了您的代码，以便能够将其作为applet或独立框架运行。我还将所有组件包装在一个面板中，并将内容窗格的布局管理器设置为GridBagLayout，因此如果调整框架大小，一切都搞定了

import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JApplet;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;

public class MyCalc extends JApplet implements ActionListener {

    /**
 * 
 */
    protected static final long serialVersionUID = 3169756252830354073L;

    private JMenuBar menuBar = new JMenuBar();
    private JMenu edit = new JMenu("Edit");
    private JMenu view = new JMenu("View");
    private JMenu help = new JMenu("Help");

    // Instantiated all JPanels used in this Applet
    //private JPanel[] rows = { new JPanel(), new JPanel(), new JPanel(),
    //      new JPanel(), new JPanel(), new JPanel(), new JPanel() };

    JTextField calc = new JTextField(1);

    private JButton[] buttons = { new JButton("Backspace"), new JButton("CE"),
            new JButton("C"), new JButton("MC"), new JButton("7"),
            new JButton("8"), new JButton("9"), new JButton("/"),
            new JButton("sqrt"), new JButton("MR"), new JButton("4"),
            new JButton("5"), new JButton("6"), new JButton("*"),
            new JButton("%"), new JButton("MS"), new JButton("1"),
            new JButton("2"), new JButton("3"), new JButton("-"),
            new JButton("1/x"), new JButton("M+"), new JButton("0"),
            new JButton("+/-"), new JButton("."), new JButton("+"),
            new JButton("=") };

    public void actionPerformed(ActionEvent e) {

        if (e.getSource() == buttons[0]) {

        }
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable(){
            public void run() {
                JFrame frame = new JFrame();
                MyCalc calc = new MyCalc();
                calc.init();
                frame.add(calc);
                frame.pack();
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public void init() {
        setName("Calculator Applet");
        menuBar.add(edit);
        menuBar.add(view);
        menuBar.add(help);
        setJMenuBar(menuBar);

        Container contentPane = getContentPane();

        calc.setText("0.");
        calc.setHorizontalAlignment(JTextField.RIGHT);
        JPanel topButtonPanel = new JPanel(new GridLayout(1, 0));
        for (int i = 0; i < 3; i++) {
            topButtonPanel.add(buttons[i]);
        }

        JPanel numberButtonPanel = new JPanel(new GridLayout(4, 6));
        for (int i = 3; i < 26; i++) {
            numberButtonPanel.add(buttons[i]);
        }

        JPanel centerWrapper = new JPanel(new BorderLayout());
        centerWrapper.add(calc, BorderLayout.PAGE_START);
        centerWrapper.add(topButtonPanel);
        centerWrapper.add(numberButtonPanel, BorderLayout.PAGE_END);

        contentPane.setLayout(new GridBagLayout());
        contentPane.add(centerWrapper);
    }
}

无法通过Calculator JApplet GUI以有序的方式显示按钮

1 个答案: