Java 计算器(我的第一个项目需要帮助)

Question

这是我第一次尝试 Java。该项目是一个计算器，它需要一个数字、一个运算符(operator)信号(+、-、*、/)和另一个数字来创建方程并给出其最终值，然后询问用户是否要重新启动程序另一个方程或不是。我想知道是否可以做些什么来改进我的代码。谢谢!

/*
Name: Felipe de Araujo
Project #: 1
*/

import java.util.Scanner; //Importing API.

public class Calculator {
public static void main(String[] args){
    int a = 1; //Creating variable for the first while loop.
    System.out.println("Welcome to the calculator!"); //Program introduction.

    while (a == 1){
        Scanner input = new Scanner(System.in); //Creating the input.

        double firstNumber, secondNumber, result; char operator; //Creating all variables.

        //Program asking for the first number.
        System.out.print("First Number: ");
        firstNumber = input.nextDouble();

        //Program asking for the operator
        System.out.print(firstNumber + " (+,-,*,/): ");
        operator = input.next(".").charAt(0);

        int repeat = 1; //Creating variable for the next while loop.

        //Evaluating the operator to determine if it is inside the criteria (+,-,*,/).
        if (operator == '+' || operator == '-' || operator == '*' || operator == '/'){
            System.out.print(firstNumber + " " + operator + " Second Number: "); //If the operator is inside the criteria than start
                                                                                 //asking for the second number.
        }
        else { //If the operator is not inside the criteria run the loop until the user type something that is.
            while (repeat == 1){
                System.out.print(operator + " not recognized, please select between (+,-,*,/): ");
                operator = input.next(".").charAt(0);
                if (operator == '+' || operator == '-' || operator == '*' || operator == '/') {
                    System.out.print(firstNumber + " " + operator + " Second Number: ");

                    repeat++;
                }
            }
        }

        secondNumber = input.nextDouble(); //Initialize the secondNumber variable to the number typed.

        //Equalling the variable result to the return given by the method calculatorMethod, with the variables given.
        result = calculatorMethod(firstNumber, secondNumber, operator);
        System.out.println(firstNumber + " " + operator + " " + secondNumber + " = " + result);//Printing the equation.
        System.out.println(" ");

        // Asking the user to continue the program for another operation.
        char out;//Creating the variable out.
        System.out.print("[y/Y] - continue | [n/N] or any other to end program: ");
        out = input.next(".").charAt(0);//Initializing the variable out to what was typed.

        //Verifying if the user wants to continue the program.
        if (out == 'y' || out == 'Y'){
            System.out.println(" ");
        }
        else {//If the users type anything besides y/Y the program will exit the main loop, ending the program.
            System.out.println("Bye!");
            a++;
        }
    }
}

//Declaring the calculatorMethod and all its behaviors.
private static double calculatorMethod(double a, double b, char c){

    if (c == '+'){
        return a + b;
    }
    else if (c == '-'){
        return  a - b;
    }
    else if (c == '*'){
        return a * b;
    }
    else {
        return a / b;
    }
}

}

Answer 1

您好，欢迎来到 Java 世界:)。一些提示:

1. 尝试为变量提供清晰的名称。 “a”、“b”、“c”可能很难理解。
2. 优先使用简短的方法来提高代码的可读性。例如，您可以创建另一种方法，该方法返回一个对象:分隔符 + 两个数字以及另一个打印结果的对象。

3. 您可以在 calculatorMethod 方法中使用 switch(variable)。例如:

   switch (c) { // you have to change the name of all the variables 'c', 'a' and 'b'
       case '+':
           return a + b;
       case '-':
           return a - b;
       case '*':
           return a * b;
       default:
           return a / b;
   }
   

   }

4. 您可以使用不同的运算符创建枚举或列表。

5. 检查输入运算符时，可以使用 while() 循环并删除 if...else 循环。 while 循环的条件可以是“当运算符不是正确的运算符(因此未包含在正确的运算符列表中)时，一次又一次循环”。

6. 扫描仪初始化Scanner input = new Scanner(System.in);应该在while()循环之外，因为您只需要初始化一次扫描仪，在本例中，您初始化 X 次(X 指循环次数)。

祝你好运:)