学习使用Java制作简易计算器的第三天

今天是使用JFormDesigner来搭建简易计算器。

一、搭建计算器页面

使用JTextField和JBottom分别来搭建输入行、输出行和按钮，然后点击红色框框，给按钮添加事件。

当然，前提是要把按钮和文本框的名字都改好，好见名知意。也好调整好他们的宽和高。

最后点击这里生成大致的图形，一般来说JFormDesigner会自动生成。

二、写代码

public static void main(String[] args) {
        Calculator calculator = new Calculator();
        calculator.setSize(435,580);
        calculator.setResizable(false);
        calculator.setVisible(true);
    }

第一次使用swing，一开始连main方法里的设置是否可见为true都忘了。

接下来是部分重要的函数。
①点击等号在answer文本框生成的答案。

private void equMouseClicked(MouseEvent e) {
        try {
            Calculate cl = new Calculate();
            String[] postfixArray;
            char[] strArray = question.getText().toCharArray();
            postfixArray = cl.convertArray(strArray);
            float val = cl.getValue(postfixArray);
            if (val == (int) val) {
                answer.setText(String.valueOf((int) val));
            } else {
                //保留三位有效数字
                String temp = String.format("%.3f",val);
                answer.setText(temp);
            }
        } catch (Exception exp) {
            answer.setText("请输入正确的运算表达式！");
        }
    }

②点击<-往后退一格

private void backMouseClicked(MouseEvent e) {
        int len = ques.length();
        try {
            ques = ques.substring(0, len - 1);
            question.setText(ques);
        } catch (Exception exp) {
            question.setText("");
        }

    }

③按钮的具体外形

//---- seven ----
        seven.setText("7");
        seven.setFocusPainted(false);
        seven.setFont(new Font("宋体",Font.BOLD,30));
        seven.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                sevenMouseClicked(e);
            }
        });
        contentPane.add(seven, "cell 0 2,wmin 60,hmin 60");

④选项中的历史记录查看

private void reMousePressed(MouseEvent e) {
        area.setFont(new Font("宋体",Font.BOLD,20));
        area.setText(reText);
        reFrame.setLocation(800,400);
        //reFrame.setTitle("record");
        reFrame.setResizable(false);
        reFrame.pack();
        reFrame.setVisible(true);
    }

三、演示

记录保存（保存最近计算的10次，多余10次会更新最旧的一条）

这里有两点缺陷，有些时候鼠标点击按键不灵，如果点击快的话，问题栏就不会更新。还有一个是因为我的数学计算是使用float类型，所以有些时候总会有一些计算上的小问题，比如 （1.2*6） 如果不保留三位有效数字的话，它在最后可能会出现比答案多或少0.0000000003（具体按情况为准），这是由于小数在计算机里存储的方式决定的。
希望对您有所帮助，也希望您能多多提意见！

四、具体代码：

package com.braden.exp1;

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

import com.braden.exp1.Calculate;
import net.miginfocom.swing.*;
/*
 * Created by JFormDesigner on Thu Dec 03 19:13:09 GMT+08:00 2020
 */



/**
 * @author Braden
 */
public class Calculator extends JFrame {

    String ques = "";
    String reText = "";
    int num = 0;
    public Calculator() {
        initComponents();
    }

    private void sevenMouseClicked(MouseEvent e) {
        ques += "7";
        question.setText(ques);
    }

    private void eightMouseClicked(MouseEvent e) {
        ques += "8";
        question.setText(ques);
    }

    private void nineMouseClicked(MouseEvent e) {
        ques += "9";
        question.setText(ques);
    }

    private void backMouseClicked(MouseEvent e) {
        int len = ques.length();
        try {
            ques = ques.substring(0, len - 1);
            question.setText(ques);
        } catch (Exception exp) {
            question.setText("");
        }

    }

    private void CMouseClicked(MouseEvent e) {
        ques = "";
        question.setText(ques);
    }

    private void fourMouseClicked(MouseEvent e) {
        ques += "4";
        question.setText(ques);
    }

    private void fiveMouseClicked(MouseEvent e) {
        ques += "5";
        question.setText(ques);
    }

    private void sixMouseClicked(MouseEvent e) {
        ques += "6";
        question.setText(ques);
    }

    private void addMouseClicked(MouseEvent e) {
        ques += "+";
        question.setText(ques);
    }

    private void subMouseClicked(MouseEvent e) {
        ques += "-";
        question.setText(ques);
    }

    private void oneMouseClicked(MouseEvent e) {
        ques += "1";
        question.setText(ques);
    }

    private void twoMouseClicked(MouseEvent e) {
        ques += "2";
        question.setText(ques);
    }

    private void threeMouseClicked(MouseEvent e) {
        ques += "3";
        question.setText(ques);
    }

    private void mulMouseClicked(MouseEvent e) {
        ques += "*";
        question.setText(ques);
    }

    private void divMouseClicked(MouseEvent e) {
        ques += "/";
        question.setText(ques);
    }

    private void zeroMouseClicked(MouseEvent e) {
        ques += "0";
        question.setText(ques);
    }

    private void dotMouseClicked(MouseEvent e) {
        ques += ".";
        question.setText(ques);
    }

    private void lBracketMouseClicked(MouseEvent e) {
        ques += "(";
        question.setText(ques);
    }

    private void rBracketMouseClicked(MouseEvent e) {
        ques += ")";
        question.setText(ques);
    }

    private void equMouseClicked(MouseEvent e) {
        try {
            Calculate cl = new Calculate();
            String[] postfixArray;
            char[] strArray = question.getText().toCharArray();
            postfixArray = cl.convertArray(strArray);
            float val = cl.getValue(postfixArray);
            if (val == (int) val) {
                answer.setText(String.valueOf((int) val));
            } else {
                //保留三位有效数字
                String temp = String.format("%.3f",val);
                answer.setText(temp);
            }
        } catch (Exception exp) {
            answer.setText("请输入正确的运算表达式！");
        } finally {
            if (num >= 10) {
                String[] tempString = reText.split("\\n");
                /*for (String i : tempString) {
                    System.out.println(i);
                }*/
                reText = "";
                for (int i = 1; i < tempString.length; i ++) {
                    reText = reText + tempString[i] + "\n";
                }
            }
            num ++;
            reText += question.getText() + " = " + answer.getText() +"\n";
        }
    }

    private void reMousePressed(MouseEvent e) {
        area.setFont(new Font("宋体",Font.BOLD,20));
        area.setText(reText);
        reFrame.setLocation(800,400);
        //reFrame.setTitle("record");
        reFrame.setResizable(false);
        reFrame.pack();
        reFrame.setVisible(true);
    }

    private void initComponents() {
        // JFormDesigner - Component initialization - DO NOT MODIFY  //GEN-BEGIN:initComponents
        question = new JTextField();
        answer = new JTextField();
        seven = new JButton();
        eight = new JButton();
        nine = new JButton();
        back = new JButton();
        C = new JButton();
        four = new JButton();
        five = new JButton();
        six = new JButton();
        add = new JButton();
        sub = new JButton();
        one = new JButton();
        two = new JButton();
        three = new JButton();
        mul = new JButton();
        div = new JButton();
        zero = new JButton();
        dot = new JButton();
        lBracket = new JButton();
        rBracket = new JButton();
        equ = new JButton();
        chooseMenu = new JMenu("选项");
        reback = new JMenuItem("历史记录");
        area = new JTextArea(11,20);
        lb = new JLabel();
        reFrame = new JFrame();

        //======== this ========
        setTitle("\u8ba1\u7b97\u5668");
        URL url = this.getClass().getResource("calpic.png");
        /*System.out.println(url);*/
        Image img = Toolkit.getDefaultToolkit().getImage(url);
        this.setIconImage(img);
        this.addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });

        Container contentPane = getContentPane();
        //---- menuBar ----
        chooseMenu.add(reback);
        JMenuBar menuBar = new JMenuBar();
        setJMenuBar(menuBar);
        menuBar.add(chooseMenu);
        area.setVisible(true);
        area.setEditable(false);
        reFrame.add(area);
        reFrame.setIconImage(img);
        reback.addMouseListener(new MouseAdapter() {
            @Override
            public void mousePressed(MouseEvent e) {
                reMousePressed(e);
            }
        });
        contentPane.setLayout(new MigLayout(
                "hidemode 3",
                // columns
                "[300,fill]",
                // rows
                "[60]" +
                        "[60]" +
                        "[60]" +
                        "[60]" +
                        "[60]" +
                        "[60]"));
        question.setFont(new Font("宋体",Font.PLAIN,25));
        answer.setFont(new Font("宋体",Font.PLAIN,25));
        answer.setEditable(false);
        contentPane.add(question, "cell 0 0,wmin 300,hmin 70");
        contentPane.add(answer, "cell 0 1,wmin 300,hmin 70");

        //---- seven ----
        seven.setText("7");
        seven.setFocusPainted(false);
        seven.setFont(new Font("宋体",Font.BOLD,30));
        seven.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                sevenMouseClicked(e);
            }
        });
        contentPane.add(seven, "cell 0 2,wmin 60,hmin 60");

        //---- eight ----
        eight.setText("8");
        eight.setFocusPainted(false);
        eight.setFont(new Font("宋体",Font.BOLD,30));
        eight.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                eightMouseClicked(e);
            }
        });
        contentPane.add(eight, "cell 0 2 10 10,wmin 60,hmin 60");

        //---- nine ----
        nine.setText("9");
        nine.setFocusPainted(false);
        nine.setFont(new Font("宋体",Font.BOLD,30));
        nine.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                nineMouseClicked(e);
            }
        });
        contentPane.add(nine, "cell 0 2 10 10,wmin 60,hmin 60");

        //---- back ----
        back.setText("<-");
        back.setFocusPainted(false);
        back.setFont(new Font("宋体",Font.BOLD,30));
        back.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                backMouseClicked(e);
            }
        });
        contentPane.add(back, "cell 0 2 10 10,wmin 60,hmin 60");

        //---- C ----
        C.setText("C");
        C.setFocusPainted(false);
        C.setFont(new Font("宋体",Font.BOLD,30));
        C.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                CMouseClicked(e);
            }
        });
        contentPane.add(C, "cell 0 2 10 10,wmin 60,hmin 60");

        //---- four ----
        four.setText("4");
        four.setFocusPainted(false);
        four.setFont(new Font("宋体",Font.BOLD,30));
        four.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                fourMouseClicked(e);
            }
        });
        contentPane.add(four, "cell 0 3,wmin 60,hmin 60");

        //---- five ----
        five.setText("5");
        five.setFocusPainted(false);
        five.setFont(new Font("宋体",Font.BOLD,30));
        five.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                fiveMouseClicked(e);
            }
        });
        contentPane.add(five, "cell 0 3,wmin 60,hmin 60");

        //---- six ----
        six.setText("6");
        six.setFocusPainted(false);
        six.setFont(new Font("宋体",Font.BOLD,30));
        six.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                sixMouseClicked(e);
            }
        });
        contentPane.add(six, "cell 0 3,wmin 60,hmin 60");

        //---- add ----
        add.setText("+");
        add.setFocusPainted(false);
        add.setFont(new Font("宋体",Font.BOLD,30));
        add.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                addMouseClicked(e);
            }
        });
        contentPane.add(add, "cell 0 3,wmin 60,hmin 60");

        //---- sub ----
        sub.setText("-");
        sub.setFocusPainted(false);
        sub.setFont(new Font("宋体",Font.BOLD,30));
        sub.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                subMouseClicked(e);
            }
        });
        contentPane.add(sub, "cell 0 3,wmin 60,hmin 60");

        //---- one ----
        one.setText("1");
        one.setFocusPainted(false);
        one.setFont(new Font("宋体",Font.BOLD,30));
        one.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                oneMouseClicked(e);
            }
        });
        contentPane.add(one, "cell 0 4,wmin 60,hmin 60");

        //---- two ----
        two.setText("2");
        two.setFocusPainted(false);
        two.setFont(new Font("宋体",Font.BOLD,30));
        two.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                twoMouseClicked(e);
            }
        });
        contentPane.add(two, "cell 0 4,wmin 60,hmin 60");

        //---- three ----
        three.setText("3");
        three.setFocusPainted(false);
        three.setFont(new Font("宋体",Font.BOLD,30));
        three.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                threeMouseClicked(e);
            }
        });
        contentPane.add(three, "cell 0 4,wmin 60,hmin 60");

        //---- mul ----
        mul.setText("*");
        mul.setFocusPainted(false);
        mul.setFont(new Font("宋体",Font.BOLD,30));
        mul.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                mulMouseClicked(e);
            }
        });
        contentPane.add(mul, "cell 0 4,wmin 60,hmin 60");

        //---- div ----
        div.setText("/");
        div.setFocusPainted(false);
        div.setFont(new Font("宋体",Font.BOLD,30));
        div.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                divMouseClicked(e);
            }
        });
        contentPane.add(div, "cell 0 4,wmin 60,hmin 60");

        //---- zero ----
        zero.setText("0");
        zero.setFocusPainted(false);
        zero.setFont(new Font("宋体",Font.BOLD,30));
        zero.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                zeroMouseClicked(e);
            }
        });
        contentPane.add(zero, "cell 0 5,wmin 60,hmin 60");

        //---- dot ----
        dot.setText(".");
        dot.setFocusPainted(false);
        dot.setFont(new Font("宋体",Font.BOLD,30));
        dot.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                dotMouseClicked(e);
            }
        });
        contentPane.add(dot, "cell 0 5,wmin 60,hmin 60");

        //---- lBracket ----
        lBracket.setText("(");
        lBracket.setFocusPainted(false);
        lBracket.setFont(new Font("宋体",Font.BOLD,30));
        lBracket.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                lBracketMouseClicked(e);
            }
        });
        contentPane.add(lBracket, "cell 0 5,wmin 60,hmin 60");

        //---- rBracket ----
        rBracket.setText(")");
        rBracket.setFocusPainted(false);
        rBracket.setFont(new Font("宋体",Font.BOLD,30));
        rBracket.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                rBracketMouseClicked(e);
            }
        });
        contentPane.add(rBracket, "cell 0 5,wmin 60,hmin 60");

        //---- equ ----
        equ.setText("=");
        equ.setFocusPainted(false);
        equ.setFont(new Font("宋体",Font.BOLD,30));
        equ.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                equMouseClicked(e);
            }
        });
        contentPane.add(equ, "cell 0 5,wmin 60,hmin 60");
        pack();
        setLocationRelativeTo(getOwner());

        // JFormDesigner - End of component initialization  //GEN-END:initComponents
    }

    // JFormDesigner - Variables declaration - DO NOT MODIFY  //GEN-BEGIN:variables
    private JTextField question;
    private JTextField answer;
    private JButton seven;
    private JButton eight;
    private JButton nine;
    private JButton back;
    private JButton C;
    private JButton four;
    private JButton five;
    private JButton six;
    private JButton add;
    private JButton sub;
    private JButton one;
    private JButton two;
    private JButton three;
    private JButton mul;
    private JButton div;
    private JButton zero;
    private JButton dot;
    private JButton lBracket;
    private JButton rBracket;
    private JButton equ;
    private JMenu chooseMenu;
    private JMenuItem reback;
    private JTextArea area;
    private JLabel lb;
    private JFrame reFrame;
    // JFormDesigner - End of variables declaration  //GEN-END:variables
    public static void main(String[] args) {
        Calculator calculator = new Calculator();
        /*Image frame_icon = Toolkit.getDefaultToolkit().createImage((".\\calpic.png"));
        calculator.setIconImage(frame_icon);*/
        calculator.setSize(435,600);
        calculator.setResizable(false);
        calculator.setVisible(true);
    }
}

本文地址：https://blog.csdn.net/qq_43632370/article/details/110633505