java写一个简易的计算器

内容相关：swing

题目要求：编写一个应用程序，设计4个按钮，分别命名为“加”、“减”、“乘”、“除”，有3个文本框。单击相应的按钮，将两个文本框的数字做运算，在第三个文本框中显示结果

思路如下：

1. 先放置所有组件在一个顶层容器中
2. 布置组件位置，我使用了GridLayout，简单方便放置组件，毕竟初学
3. 写出四个计算按钮的buttonaction，获取textfield中的值并计算，然后将值放入textarea中
4. 写个顶层菜单玩玩，包括一个退出，一个应用信息，暂时还未涉及文件io，见谅

代码如下：

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.image.Kernel;
import java.text.DecimalFormat;

public class e4_1 {


    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                caculateGUI();
            }
        });
    }
    private static void caculateGUI(){
        JFrame.setDefaultLookAndFeelDecorated(true);
        JFrame frame = new JFrame();
        frame.setTitle("caculator");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setTitle("caculator");
        frame.setLayout(new GridLayout(5,2));

        //add menubar
        JMenuBar jMenuBar = new JMenuBar();
        JMenu operationMenu = new JMenu("operation");
        JMenu helpMenu = new JMenu("help");
        jMenuBar.add(operationMenu);
        jMenuBar.add(helpMenu);

        //add exit actionlistener
        JMenuItem operationExitMI = new JMenuItem("Exit");
        operationMenu.add(operationExitMI);
        operationExitMI.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                System.exit(0);
            }
        });

        // add information actionlistener
        JMenuItem helpInformationMI = new JMenuItem("Information");
        helpMenu.add(helpInformationMI);
        helpInformationMI.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                JOptionPane.showOptionDialog(null,
                          "program name:  caculator \n"
                                 + "information :  trash\n"
                                + " created by  :  ChrisTree\n"
                                  +"\n"
                                +"fuck the world\n"+"i love zhangyan forever\n",
                        "caculator information", JOptionPane.DEFAULT_OPTION,
                        JOptionPane.INFORMATION_MESSAGE, null, null, null);
            }
        });

        //set menubar
        frame.setJMenuBar(jMenuBar);
        frame.setSize(200, 100);
        frame.setVisible(true);


        //add label
        frame.add(new JLabel("1st num"));
        frame.add(new JLabel("2nd num"));

        //creat and add textfield
        JTextField textField1 = new JTextField();
        JTextField textField2 = new JTextField();
        frame.add(textField1);
        frame.add(textField2);


        //add result_label and result_textarea
        frame.add(new JLabel("result"));
        JTextArea jTextArea = new JTextArea();
        frame.add(jTextArea);


        //creat buttons
        JButton jButton1 = new JButton("+");
        JButton jButton2 = new JButton("-");
        JButton jButton3 = new JButton("*");
        JButton jButton4 = new JButton("/");


        //buttonActions
        frame.add(jButton1);
        jButton1.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                int a = Integer.parseInt(textField1.getText());
                int b = Integer.parseInt(textField2.getText());
                jTextArea.setText(Integer.toString(a+b));
            }
        });

        frame.add(jButton2);
        jButton2.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                int a = Integer.parseInt(textField1.getText());
                int b = Integer.parseInt(textField2.getText());
                jTextArea.setText(Integer.toString(a-b));
            }
        });

        frame.add(jButton3);
        jButton3.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                int a = Integer.parseInt(textField1.getText());
                int b = Integer.parseInt(textField2.getText());
                jTextArea.setText(Integer.toString(a*b));
            }
        });

        frame.add(jButton4);
        jButton4.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                double a = Double.parseDouble(textField1.getText());
                double b = Double.parseDouble(textField2.getText());
                jTextArea.setText(Double.toString(a/b));
            }
        });

        int frameWidth = 400;
        int frameHeight = 800;
        Dimension screenSize =
                Toolkit.getDefaultToolkit().getScreenSize();
        frame.setBounds((int)screenSize.getWidth() - frameWidth,0,frameWidth,frameHeight);
        frame.setVisible(true);

    }

}

如需代码，请修改

 helpInformationMI.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                JOptionPane.showOptionDialog(null,
                          "program name:  caculator \n"
                                 + "information :  trash\n"
                                + " created by  :  ChrisTree\n"
                                  +"\n"
                                +"fuck the world\n"+"i love zhangyan forever\n",
                        "caculator information", JOptionPane.DEFAULT_OPTION,
                        JOptionPane.INFORMATION_MESSAGE, null, null, null);
            }
        });

其中showOptionDialog对话框中的内容

或者删除//add menu 注释到//add label 注释之间的内容

编辑于2018/05/30
如有疏漏或者问题，欢迎私信与我探讨,我会虚心接受教导。
[email protected]