如何使用Java计算器计算一个操作数？

我尝试用Java创建一个简单的计算器已有一段时间了，我已经成功地使程序能够使用两个操作数方程（+、-、*、/、和^）。但是，我想知道如何才能解决一个操作数的数学问题—绝对值（使用符号“|”）、平方根（使用符号“v”）、舍入到最接近的整数（使用符号“~”）、sin（s）、cos（c）和切线（t）

我尝试了绝对值操作数，可以在以下内容中看到：

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

以及：

此代码仅在您输入值时有效，例如：

-3 |-3

（注意：我注意到它只是执行绝对值操作的第一个数字。第二个数字可以是您想要的任何数字（如果您输入

-3 |-4

，您的答案仍然是

3

）只要它确实是一个数字

如果您能为解决此问题提供任何帮助，并帮助您找出其他单操作数操作，我们将不胜感激

提前谢谢

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;
    }


}

package计算器；
导入java.util.Scanner；
公共类计算器{
公共静态void main（字符串[]args）{
System.out.println（“您好，欢迎使用我的计算器”）；
System.out.println（“输入一些您希望我计算的内容”）；
扫描仪扫描=新扫描仪（System.in）；
System.out.println（“如果需要帮助，请键入“帮助”）；
System.out.println（“如果您想随时离开，请键入\“退出\”）；
System.out.println（“按回车键继续”）；
字符串s1=scan.nextLine（）；
如果（s1.等于（“帮助”））{
System.out.println（“”）；
System.out.println（“双操作数命令：”）；
System.out.println（“加法：'+'（例如：'a+b'）”；
System.out.println（“减法：'-'（例如：'a-b'）”；
System.out.println（“乘法：'*'（例如：'a*b'）”；
System.out.println（“部门：'/'（例如：“a/b”）；
System.out.println（“指数：'^'（例如：'a^b'）”；
System.out.println（“”）；
}
扫描仪输入=新扫描仪（System.in）；
数学=新数学；
双答案=0；
双核，麻木；
字符算子；
布尔退出=假；
while（true）{
System.out.print（“请输入公式：”）；
字符串s=input.next（）；
如果（s.equals（“退出”））{
System.out.println（“感谢您使用我的程序！”）；
系统出口（0）；
}
numA=Double.parseDouble（s）；
运算符=输入.next（）.charAt（0）；
numB=input.nextDouble（）；
if（运算符=='+'）{
答案=数学。加（numA，numB）；
}
if（运算符=='-'）{
答案=数学。减法（numA，numB）；
}
如果（运算符=='*'）{
答案=数学。乘法（numA，numB）；
}
if（运算符=='/'））{
答案=数学。除法（numA，numB）；
}
if（运算符=='^'）{
答案=数学。力量（numA，麻木）；
}
if（运算符==“|”）{
答案=Math.abs（numA）；
}
System.out.println（应答）；
}
}
}
课堂数学{
双加（双a，双b）{
双重回答=a+b；
返回答案；
}
双减法（双a，双b）{
双重回答=a-b；
返回答案；
}
双乘（双a，双b）{
双重回答=a*b；
返回答案；
}
双除法（双a，双b）{
双重回答=a/b；
返回答案；
}
双电源（双a、双b）{
双重回答=a；
对于（int x=2；x使用正则表达式检查第一个数字是否实际上是一个数字。然后执行相应的操作。此外，您可以使用正则异常处理错误的用户输入。因此，如果输入“3+3”，您将不会有
java.lang.NumberFormatException
s

我对您现有的代码进行了一些修改，使其能够适应所有情况，并允许将来扩展函数。您可以通过注释了解更改。此外，如果用户只为函数提供一个输入，并且只有一个参数就足够，则代码将能够运行。我没有更改您的任何函数

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;
        }

    }

}

除非操作员需要，否则不要执行
numB=input.nextDouble（）
。@谢谢！我该怎么做呢？不是很优雅，但如果需要，您可以将该行移到
中的每一行（operator=
需要它的块。这是可行的…但就像你说的，不是很优雅，我有点想把操作数放在所说的数字之前，而不是后面。在这种情况下，你最好把整行作为一个字符串来读，并根据需要对其进行解析。（看第一个词，看看它是否是一个可以去那里的操作员等）谢谢塔瑞克…出于好奇，有没有办法做同样的事情…除了不使用Rebecca你说的Rebecca是什么意思？Regex？如果你指的是Regex，那么是的，有办法。但是Regex是最好的，而且很容易学习。
if (s.matches("^[-+]?[0-9]*\\.?[0-9]+$")) { //Check whether first number is actually a number
    numA = Double.parseDouble(s);
    operator = input.next().charAt(0);
    numB = input.nextDouble();

} else {
    operator = s.charAt(0);
    numA = input.nextDouble();
    numB = 0;
}

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;
        }

    }

}

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