如何讓計算器詢問用戶是否想在 Java 中執行另一個計算？

Question

我嘗試使用 do while 循環來執行此操作，但是找不到該變量。 我的目標是基本上在用戶想要的時候重新執行代碼。 有人可以幫忙嗎？

import java.util.Scanner;
public class Calculator {
    public static void main(String args[]) {
        do{
            Scanner typed=new Scanner(System.in);
            System.out.println("Please type: 1 for add, 2 for subtract, 3 for multiply or 4 for divide");
            int userInput=typed.nextInt();
            System.out.println("Please enter the first number to calculate:");
            double number1=typed.nextDouble();
            System.out.println("Please enter the second number to calculate:");
            double number2=typed.nextDouble();
            if (userInput==1){
                System.out.println("The answer is");
                double result=number1+number2;
                System.out.println(result);
            }
            if (userInput==2){
                System.out.println("The answer is");
                double result=number1-number2;
                System.out.println(result);
            }
            if (userInput==3){
                System.out.println("The answer is");
                double result=number1*number2;
                System.out.println(result);
            }
            if (userInput==4){
                System.out.println("The answer is");
                double result=number1/number2;
                System.out.println(result);
            }
                System.out.println("Do you want to perform another calculation? Press 1 for yes or 2 for no.");
                int pressed=typed.nextInt();
            
        }while(pressed==1);
            
    }
}

Answer 1

您正在嘗試使用其范圍之外的變量。

    do{
      // ...
      int pressed=typed.nextInt();
        
    }while(pressed==1);  // Outside of the scope of 'pressed'

您可以通過將聲明移到循環外但保留分配來解決此問題。

    int pressed = 1;

    do{
      // ...
      pressed=typed.nextInt();
        
    }while(pressed==1);  // Outside of the scope of 'pressed'

Answer 2

pressed在循環主體之后留下范圍。 將 press 的聲明pressed do之前。

int pressed = 0;
do {
    // ...
    pressed=typed.nextInt();
} while(pressed==1);

或者，您可以將循環更改為無限循環while(true); 並使用

int pressed = typed.nextInt();
if (pressed != 1) {
    break; // End the infinite loop
}

Answer 3

只需在 do while 循環之外聲明“按下”變量。

int pressed;
do 
{
 //code
}

並從int pressed=typed.nextInt(); 這一行使其變為pressed=typed.nextInt();