Java 浮点除法的显式类型转换

Question

我不确定是否在选项 4(除法)中对浮点除法使用显式类型转换。我需要一些帮助来理解什么是浮点除法。

我必须使用整数来存储 2 个操作数，使用 double 来存储结果。您必须对选项 4 中的浮点除法使用显式类型转换。还可以使用 switch 语句来处理菜单选项。每次计算后

import java.util.Scanner;

public class SimpleCalculator
{
   //-----------------------------------------------------------------
   //  Calculates two integers 
   //  using values entered by the user.
   //-----------------------------------------------------------------
    public static void main(String[] args) 
    {
        //Variables
        final int ADDITION = 1,SUBTRACTION = 2, MULTIPLICATION = 3,DIVISION = 4, EXIT = 5;
        int num1 = 0, num2 = 0, choice = 0;
        double dblNum1, dblNum2, result;
        String equation = "";

        do
        {
            //Processing
            equation = "";
            Scanner scan = new Scanner(System.in);
            System.out.println("Choose from the following: ");
            System.out.println("1. Add 2 integers");
            System.out.println("2. Subtract 2 integers");
            System.out.println("3. Multiply 2 integers");
            System.out.println("4. Divide 2 integers");
            System.out.println("5. Exit");
            System.out.print("Enter choice: ");

            choice = scan.nextInt();

                if(choice < 5 && choice > 0)//keeps program from asking for two numbers if exiting
                {
                    System.out.print("Enter first integer: ");
                    num1 = scan.nextInt();

                    System.out.print("Enter second integer: ");
                    num2 = scan.nextInt();
                }

            //switch for operations
            switch (choice)
            {
                case ADDITION:
                    result = num1 + num2;
                    equation = ((num1) + " + " + (num2) + " = "+ result);
                    break;

                case SUBTRACTION:
                    result = num1 - num2;
                    equation = ((num1) + " - " + (num2) + " = "+ result);
                    break;

                case MULTIPLICATION:
                    result = num1 * num2;
                    equation = ((num1) + " * " + (num2) + " = "+ result);
                    break;

                case DIVISION:
                    if(num2 == 0)//when denominator becomes zero
                    {
                        System.out.println("DIVISION NOT POSSIBLE");
                        break;
                    }
                    dblNum1 = num1;//convert int to double
                    dblNum2 = num2;
                    result = dblNum1/dblNum2;
                    equation = ((num1) + "/" + (num2) + " = "+ result);
                    break;

                case EXIT:
                    System.exit(0);
                    break;

                default:
                    System.out.println("YOU HAVE ENTERED AN INCORRECT CHOICE");             
            }
            //Output
            System.out.println(equation);
            System.out.println();
        }while(choice != EXIT);
    }
}

Answer 1

不，这不是明确的类型转换。你会想使用这样的东西:

result = ((double) num1) / ((double) num2);

实际上，由于 / 运算符的扩展规则，您只需要这些显式转换之一，但同时拥有两者也没有坏处。事实上，由于强制转换运算符 () 的优先级高于除法运算符 /，因此您可以将其写为:

result = (double) num1 / num2;

它结合了分子的显式转换和分母的隐式转换。