当用户输入“结束”时如何结束这个程序？

Question

所以基本上我想弄清楚如何使用Integer.valueOf(String s) 或Integer.parseInt(String s) 通过为用户输入键入“end”来停止这个程序

import java.util.Scanner;

public class monkey1{
    public static void main(String[] args){
        Scanner s = new Scanner(System.in);
        int sum = 0;
        int lol = 1;
        do { 
            System.out.print("Enter a number: ");
            lol = s.nextInt();
            sum += lol;
            if (lol > 0) {
                System.out.println("Sum is now: " + sum);
            }
        } while (lol>0);
    }
}

Answer 1

首先 - 您需要将 lol=sc.nextInt() 更改为 String tmp = s.nextLine()

第二个 - 做

try {
   if (tmp.equals("END")) {
       break;  // This will exit do-while loop
   }
   lol = Integer.parseInt(tmp);
} catch (NumberFormatException e) {
  e.printStackTrace();
  // Here you can also exit loop by adding break. Or just ask user to enter new text.
}

Answer 2

您应该学习如何使用 try/catch。 我们开始：

String text = "";
    int lol = 1;
    do {
        System.out.print("Enter a number: ");
        text = s.nextLine();
        try {
            lol = Integer.valueOf(text);
        }catch (Exception e){
            System.out.println("Exit");
            System.exit(0);
        }

Answer 3

这是你的代码

package Phone;

import java.util.Scanner;

public class monkey1{
    public static void main(String[] args){
        Scanner s = new Scanner(System.in);
        int sum = 0;
        int hi = 1;
        do { 
            System.out.print("Enter a number: ");
            String lol = s.nextLine();
            if(lol.equals("end")) {
                break;
        }

        hi = Integer.parseInt(lol);

        sum += hi;
        if (hi > 0) {
            System.out.println("Sum is now: " + sum);
        }
    } while (hi > 0);
}

我在这里所做的是我将 lol 更改为 hi 以添加并接受 String 输入，以便您可以输入 end...

Answer 4

我建议在转换为 int 之前检查 if s.equals("end") 是这样的：

do { 
        System.out.print("Enter a number: ");
        String userValue = s.nextLine();
        if(userValue.equals("end")
            break;
        lol = Integer.parseInt(userValue);
        sum += lol;
        if (lol > 0){
            System.out.println("Sum is now: " + sum);
        }
    }while (lol>0);