JAVA——简单科学计算器设计

package Calculator_JCoder;

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.text.DecimalFormat;
import javax.swing.*;
import java.util.*;
import java.math.*;

public class Calculator extends JFrame implements ActionListener {
    static Font F = new Font("宋体",Font.BOLD,25);
    static Font _F = new Font("宋体",Font.BOLD,40);
    static DecimalFormat DF = new DecimalFormat("0.0000000000");
    static String IN = "";
    static JTextField Text_Res = new JTextField("0");
    static JTextField Text_Now = new JTextField("");
    static JButton Keys[] = new JButton[21];
    static String KeysName[] = {
            "7", "8", "9", "4", "5", "6", "1", "2",
            "3", "0", ".", "+", "-", "*", "/", "=",
            "CE", "(", ")", "^", "C"
    };

    static int CMP(char a){
        if(a == ‘#‘){return 0;}
        if(a == ‘(‘){return 1;}
        if(a == ‘+‘ || a == ‘-‘){return 3;}
        if(a == ‘*‘ || a == ‘/‘){return 4;}
        if(a == ‘^‘){return 5;}
        if(a == ‘)‘){return 6;}
        return -1;
    }

    static String Change(String in){
        in += "#";
        int L = in.length();
        String t = "";
        String NPR = "";
        Stack<Character> S = new Stack();
        for(int i = 0;i < L;i ++){
            if(in.charAt(i) >= ‘0‘ && in.charAt(i) <= ‘9‘){t += in.charAt(i);}
            else if(in.charAt(i) == ‘.‘){t += in.charAt(i);}
            else if(in.charAt(i) == ‘#‘){
                if(t.length() != 0){NPR += t + " ";}
                t = "";
            }
            else if(in.charAt(i) == ‘+‘ || in.charAt(i) == ‘-‘ || in.charAt(i) == ‘*‘ || in.charAt(i) == ‘/‘ || in.charAt(i) == ‘^‘){
                if(t.length() != 0){NPR += t + " ";}
                t = "";
                if(S.size() == 0){
                    S.push(in.charAt(i));
                }
                else if(CMP(S.peek()) < CMP(in.charAt(i))){
                    S.push(in.charAt(i));
                }
                else if(CMP(S.peek()) >= CMP(in.charAt(i))){
                    NPR += S.peek() + " ";
                    S.pop();
                    S.push(in.charAt(i));
                }
            }
            else if(in.charAt(i) == ‘(‘){
                if(t.length() != 0){NPR += t + " ";}
                t = "";
                S.push(in.charAt(i));
            }
            else if(in.charAt(i) == ‘)‘){
                if(t.length() != 0){NPR += t + " ";}
                t = "";
                while(S.peek() != ‘(‘){
                    NPR += S.peek() + " ";
                    S.pop();
                }
                S.pop();
            }
        }
        while(S.size() != 0){
            NPR += S.peek() + " ";
            S.pop();
        }
        //System.out.println(NPR);
        return NPR;
    }

    static double Solve(double a,double b,char c){
        double out = 0.0;
        if(c == ‘+‘){
            out = a + b;
        }
        else if(c == ‘-‘){
            out = a - b;
        }
        else if(c == ‘*‘){
            out = a * b;
        }
        else if(c == ‘/‘){
            out = a / b;
        }
        else if(c == ‘^‘){
            out = Math.pow(a,b);
        }
        return out;
    }

    static double Cal(String now){
        String Sp[] = now.split("\\ ");
        Stack<Double> S = new Stack();
        for(int i = 0;i < Sp.length;i ++){
            if(Sp[i].length() == 0){continue;}
            if(Sp[i].charAt(0) <= ‘9‘ && Sp[i].charAt(0) >= ‘0‘){
                S.push(Double.valueOf(Sp[i]));
            }
            else{
                double b = S.peek();S.pop();
                double a = S.peek();S.pop();
                double c = Solve(a,b,Sp[i].charAt(0));
                S.push(c);
            }
        }
        double ans = S.peek();
        return ans;
    }

    static String SetS(int x){
        if(x == 1){return "+";}
        if(x == 2){return "-";}
        if(x == 3){return "*";}
        if(x == 4){return "/";}
        return "0";
    }

    public void init() {
        JPanel KeysP = new JPanel();
        KeysP.setLayout(null);
        KeysP.setSize(500,500);
        for(int i = 0;i <= 20;i ++){
            Keys[i] = new JButton(KeysName[i]);
            KeysP.add(Keys[i]);
            Keys[i].setFont(F);
        }
        Keys[0].setBounds(20,20,60,60);
        Keys[1].setBounds(85,20,60,60);
        Keys[2].setBounds(150,20,60,60);
        Keys[3].setBounds(20,85,60,60);
        Keys[4].setBounds(85,85,60,60);
        Keys[5].setBounds(150,85,60,60);
        Keys[6].setBounds(20,150,60,60);
        Keys[7].setBounds(85,150,60,60);
        Keys[8].setBounds(150,150,60,60);
        Keys[9].setBounds(20,215,125,60);
        Keys[10].setBounds(150,215,60,60);
        Keys[11].setBounds(215,20,60,60);
        Keys[12].setBounds(280,20,60,60);
        Keys[13].setBounds(215,85,60,60);
        Keys[14].setBounds(280,85,60,60);
        Keys[15].setBounds(215,150,125,60);
        Keys[16].setBounds(215,215,125,60);
        Keys[17].setBounds(345,20,60,60);
        Keys[18].setBounds(345,85,60,60);
        Keys[19].setBounds(345,150,60,60);
        Keys[20].setBounds(345,215,60,60);    

        Text_Res.setHorizontalAlignment(JTextField.RIGHT);
        Text_Now.setHorizontalAlignment(JTextField.RIGHT);
        Text_Res.setEditable(false);
        Text_Now.setEditable(false);
        Text_Res.setBackground(Color.WHITE);
        Text_Now.setBackground(Color.WHITE);
        JPanel TextP = new JPanel();
        TextP.setLayout(null);
        TextP.setSize(500,100);
        TextP.add(Text_Res);
        Text_Res.setBounds(20, 60, 385, 60);
        TextP.add(Text_Now);
        Text_Now.setBounds(20, 20, 385, 40);
        Text_Res.setFont(_F);
        Text_Now.setFont(F);

        JPanel BigP = new JPanel();
        BigP.setSize(800,600);
        BigP.setLayout(null);
        BigP.add(KeysP);
        BigP.add(TextP);
        KeysP.setBounds(0, 120, 600, 600);
        TextP.setBounds(0, 0, 500, 200);
        getContentPane().setLayout(null);
        getContentPane().add(BigP);

        for (int i = 0; i <= 20; i ++) {
            Keys[i].addActionListener(this);
        }

    }

    public void actionPerformed(ActionEvent e) {
        String Get = e.getActionCommand();
        if("0123456789.+-*/^()".indexOf(Get) >= 0){
            IN = IN + Get;
            Text_Now.setText(IN);
        }
        else if("=".indexOf(Get) >= 0){
            double show = Cal(Change(IN));
            //System.out.println(show);
            //System.out.println(show);
            String t1 = String.valueOf(show);
            String t2 = String.valueOf(DF.format(show));
            Text_Res.setText(t1);
            IN = t2;
        }
        else if("CE".compareTo(Get) == 0){
            int L = IN.length();
            if(L != 0){IN = IN.substring(0,L - 1);}
            Text_Now.setText(IN);
        }
        else if("C".compareTo(Get) == 0){
            IN = "";
            Text_Now.setText(IN);
            Text_Res.setText("0");
        }
    }

    public Calculator(){
        super();
        init();
        this.setTitle("Calculator By-J_Coder");
        this.setResizable(false);
        this.setLocation(100,100);
        this.setSize(440,450);
    }

    public static void main(String[] args) {
        Calculator window = new Calculator();
        window.setVisible(true);
        window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
}

原文地址：https://www.cnblogs.com/love-fromAtoZ/p/9704113.html