java - 如何使用 Java 计算器进行单操作数数学运算？

Question

我已经尝试用 Java 创建一个简单的计算器有一段时间了，并且我已经成功地使该程序能够使用双操作数方程(+、-、*、/和 ^)。然而，我想知道如何能够做单操作数数学问题 - 绝对值(使用符号“|”)，平方根(使用符号“v”)，四舍五入到最接近的整数(使用符号“~')、sin (s)、cos (c) 和 tangent (t)。

我尝试了绝对值操作数，可以在以下位置看到:

if (operator == '|') {
            answer = Math.abs(numA);
}
// In the main class

和:

double absolute(double a) {
            double answer = Math.abs(a);
            return answer;
}
// In the maths class

此代码仅在您输入如下值时才有效:-3 | -3 (注意:我注意到这只是执行绝对值运算的第一个数字。第二个数字可以是您想要的任何数字(如果您输入 -3 | -4 你的答案仍然是 3)，只要它确实是一个数字。

任何解决此问题的帮助以及帮助找出其他单操作数运算的帮助将不胜感激!

提前致谢!

我的程序的源代码如下:

package calculator;
import java.util.Scanner;

public class Calculator {

public static void main(String[] args) {

    System.out.println("Hello, welcome to my calculator");
    System.out.println("Enter in some stuff you want to me to calculate");

    Scanner scan = new Scanner(System.in);
    System.out.println("If you need help please type \"help\"");
    System.out.println("If at anytime you want to leave, type \"quit\"");
    System.out.println("Hit enter to continue.");

    String s1 = scan.nextLine();

    if (s1.equals("help")){
        System.out.println(" ");

        System.out.println("Double operand commands:");
        System.out.println("Addition: '+' (Ex: 'a + b' )");
        System.out.println("Subtraction: '-' (Ex: 'a - b' )");
        System.out.println("Multiplication: '*' (Ex: 'a * b' ) ");
        System.out.println("Division: '/' (Ex: 'a / b' )");
        System.out.println("Exponents: '^' (Ex: 'a ^ b' )");

        System.out.println(" ");
    }

    Scanner input = new Scanner(System.in);

    Maths maths = new Maths();

    double answer = 0;
    double numA, numB;
    char operator;
    boolean quit = false;


    while (true) {

    System.out.print("Please enter your equation: ");

    String s=input.next();

    if(s.equals("quit")){
        System.out.println("Thank you for using my program!");
        System.exit(0);
    }

    numA = Double.parseDouble(s);
    operator = input.next().charAt(0);
    numB = input.nextDouble();        

    if (operator == '+') {
        answer = maths.add(numA, numB);
    }

    if (operator == '-') {
        answer = maths.subtract(numA, numB);
    }

    if (operator == '*') {
        answer = maths.multiply(numA, numB);
    }

    if (operator == '/') {
        answer = maths.divide(numA, numB);
    }

    if (operator == '^') {
        answer = maths.power(numA, numB);
    }

    if (operator == '|') {
        answer = Math.abs(numA);
    }

        System.out.println(answer);        



        }

    }

}

class Maths {

    double add(double a, double b) {
        double answer = a+b;
        return answer;          
    }

    double subtract(double a, double b) {
        double answer = a-b;
        return answer;          
    }

    double multiply(double a, double b) {
        double answer = a*b;
        return answer;          
    }

    double divide(double a, double b) {
        double answer = a/b;
        return answer;          
    }

    double power(double a, double b){
        double answer =a;

        for (int x=2; x<=b; x++){
            answer *= a;
        }

        return answer;
    }

    double absolute(double a) {
        double answer = Math.abs(a);
        return answer;
    }


}

Answer 1

我对您现有的代码做了一些修改，以便它适合所有情况并允许将来扩展功能。您可以通过评论了解更改。此外，如果用户只为函数提供一个输入(其中只有一个参数就足够了)，则代码将能够运行。我没有改变你的任何功能。

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Scanner;

public class Calculator {

    public static void main(String[] args) {

        System.out.println("Hello, welcome to my calculator");
        System.out.println("Enter in some stuff you want to me to calculate");

        Scanner scan = new Scanner(System.in);
        System.out.println("If you need help please type \"help\"");
        System.out.println("If at anytime you want to leave, type \"quit\"");
        System.out.println("Hit enter to continue.");

        String s1 = scan.nextLine();

        if (s1.equals("help")) {
            System.out.println(" ");

            System.out.println("Double operand commands:");
            System.out.println("Addition: '+' (Ex: 'a + b' )");
            System.out.println("Subtraction: '-' (Ex: 'a - b' )");
            System.out.println("Multiplication: '*' (Ex: 'a * b' ) ");
            System.out.println("Division: '/' (Ex: 'a / b' )");
            System.out.println("Exponents: '^' (Ex: 'a ^ b' )");

            System.out.println(" ");
        } else if (s1.equals("quit")) {
            System.out.println("Thank you for using my program!");
            System.exit(0);
        }

        Scanner input = new Scanner(System.in);


        Maths maths = new Maths();

        double answer = 0;
        double numA=0.0, numB=0.0;
        char operator;
        boolean quit = false;

        while (true) {

            System.out.print("Please enter your equation: ");

            //First scan the function as a string
            String s = input.next();

            if (s.equals("quit")) {
                System.out.println("Thank you for using my program!");
                System.exit(0);
            }

          //We will use regex to find the operator, so we will omit all alphabetic letter or numeric number or decimal
            String operator1 = s.replaceAll("[a-zA-Z0-9.]",""); 
          //For functions like -4|, the operator1 will be -| after replacing through regex, we will only take the second digit as operator to prevent error
            if(operator1.length()==1) 
            operator = operator1.charAt(0);
            else
                operator = operator1.charAt(1); 
            String[] num11 = (s.split("[^0-9,.]"));
        //String array num11 may contain null string after splitting using regex, we will remove those null string and store only variable values in an arraylist
           ArrayList<String> arraylist = new ArrayList<String>();

            for (int i = 0; i < num11.length; i++)
            {
                if (!num11[i].equals(""))
                {
                    arraylist.add(num11[i]);
                }
            }



            if(arraylist.size()==1){
            numA = Double.parseDouble(arraylist.get(0));    
            numB=numA;}
            else if(arraylist.size()==2){
            numA = Double.parseDouble(arraylist.get(0));    
            numB = Double.parseDouble(arraylist.get(1));

            }




            if (operator == '+') {
                answer = maths.add(numA, numB);
            }

            if (operator == '-') {
                answer = maths.subtract(numA, numB);
            }

            if (operator == '*') {
                answer = maths.multiply(numA, numB);
            }

            if (operator == '/') {
                answer = maths.divide(numA, numB);
            }

            if (operator == '^') {
                answer = maths.power(numA, numB);
            }

            if (operator == '|') {
                answer = Math.abs(numA);
            }

            System.out.println(answer);

        }

    }

    public static class Maths {

        public void Maths(){};

        double add(double a, double b) {
            double answer = a + b;
            return answer;
        }

        double subtract(double a, double b) {
            double answer = a - b;
            return answer;
        }

        double multiply(double a, double b) {
            double answer = a * b;
            return answer;
        }

        double divide(double a, double b) {
            double answer = a / b;
            return answer;
        }

        double power(double a, double b) {
            double answer = a;

            for (int x = 2; x <= b; x++) {
                answer *= a;
            }

            return answer;
        }

        double absolute(double a) {
            double answer = Math.abs(a);
            return answer;
        }

    }

}

输出:

Please enter your equation: +4+4
8.0
Please enter your equation: 4+4
8.0
Please enter your equation: 4+3
7.0
Please enter your equation: 4-3
1.0
Please enter your equation: 4/3
1.3333333333333333
Please enter your equation: -4|
4.0
Please enter your equation: 4|
4.0
Please enter your equation: 3^2
9.0