如何在所有计算中使用相同的数字

Question

import java.util.Scanner; 
public class Calculator 
{ 
    public static void main(String args[]) 
    { 
     System.out.println("Enter the numbers only "); 
     Scanner num =new Scanner(System.in); 
     System.out.println("Enter the number of times you want to run loop "); 
     Scanner loop =new Scanner(System.in); 
     int n =loop.nextInt(); 
     while(n!=0) 
     { 
      System.out.println("Enter the Cases 1 for addition,2 for Subtraction,3 for Division 4 for multipication and 5 for reaminder "); 
      Scanner cas =new Scanner(System.in); 
      int c = cas.nextInt(); 
      double calc,first,second; 
      switch (c) 
      { 
      case 1: 
       System.out.println("addition of two number is "); 
       first = num.nextDouble(); 
       second=num.nextDouble(); 
       calc = first + second; 
       System.out.println(calc); 
       break; 
      case 2: 
       System.out.println("subtraction of two number is "); 
       first = num.nextDouble(); 
       second = num.nextDouble(); 
       calc = first - second;  
       System.out.println(calc); 
       break; 
      case 3: 
       System.out.println("division of two number is "); 
       first = num.nextDouble(); 
       second = num.nextDouble(); 
       calc = first/second; 
       System.out.println(calc); 
       break; 
      case 4: 
       System.out.println("multipication of two number is "); 
       first = num.nextDouble(); 
       second = num.nextDouble(); 
       calc = first * second; 
       System.out.println(calc); 
       break; 
      case 5: 
       System.out.println("remainder of two number is "); 
       first = num.nextDouble(); 
       second = num.nextDouble(); 
       calc = first % second; 
       System.out.println(calc); 
       break; 
      default: 
       System.out.println("you did not enter 1,2,3,4,5 you entered something else "); 
      } 
     n--; 
     } 
     System.out.println("the program has end, THANK YOU!!"); 
    } 
} 

这是通过询问用户输入来计算的java代码。我如何在这段代码中对所有计算使用相同的数字？它每次都要求用户输入新的数字，但是我希望此代码只通过一个输入来完成所有计算。

Answer 1

你需要调用

first = num.nextDouble(); 
second = num.nextDouble(); 

只有一次。把它叫做你希望用户输入数字的地方。

对于你的榜样，你应该把它改成这样：

import java.util.Scanner; 
public class Calculator 
{ 
    public static void main(String args[]) 
    { 
     System.out.println("Enter the numbers only "); 
     Scanner num =new Scanner(System.in); 
     double first,second; 
     first = num.nextDouble(); //Get first number 
     second = num.nextDouble(); //Get second number 
     System.out.println("Enter the number of times you want to run loop  "); 
     Scanner loop =new Scanner(System.in); 
     int n =loop.nextInt(); 
     while(n!=0) 
     { 
      System.out.println("Enter the Cases 1 for addition,2 for  Subtraction,3 for Division 4 for multipication and 5 for reaminder "); 
      Scanner cas =new Scanner(System.in); 
      int c = cas.nextInt(); 
      double calc; 
      switch (c) 
      { 
      case 1: 
       System.out.println("addition of two number is "); 
       calc = first + second; 
       System.out.println(calc); 
       break; 
      case 2: 
       System.out.println("subtraction of two number is "); 
       calc = first - second;  
       System.out.println(calc); 
       break; 
      case 3: 
       System.out.println("division of two number is "); 
       calc = first/second; 
       System.out.println(calc); 
       break; 
      case 4: 
       System.out.println("multipication of two number is "); 
       calc = first * second; 
       System.out.println(calc); 
       break; 
      case 5: 
       System.out.println("remainder of two number is "); 
       calc = first % second; 
       System.out.println(calc); 
       break; 
      default: 
       System.out.println("you did not enter 1,2,3,4,5 you entered  something else "); 
      } 
     n--; 
     } 
     System.out.println("the program has end, THANK YOU!!"); 
    } 
} 

Answer 2

如果删除

休息;

从每一个情况下，它会做所有的情况下，从一个用户选择

开始这是你想要的吗？