Question

我试图提示用户输入一个数字，然后询问他们是否要输入另一个。如果是，则重新启动第一个while循环，如果否，则退出以打印所选数字。

但是，无论我做什么，似乎都无法摆脱第一个循环。它只是不断重复编号。

我尝试将userInput =“ y”断开，然后在有效= true的末尾继续；当前是，它们都产生相同的结果。

陷入无限循环。

ArrayList<Integer> inputs = new ArrayList<Integer>();
System.out.println("Enter some numbers: ");

   String userInput = "y"; 
    boolean valid = false;

    do {
        while (scnr.hasNextInt()) {
           inputs.add(scnr.nextInt());
           System.out.println("Would you like to enter another?");
           valid = true;
           }
           System.out.println(inputs);

    } while (!userInput.equalsIgnoreCase("n"));

Answer 1

问题在于您没有突破内循环。在这里，我将如何编写相同的代码：

import java.util.ArrayList;
import java.util.Scanner;

public class ReadNumbers {
  public static void main(String[] args) {
    ArrayList<Integer> inputs = new ArrayList<Integer>();
    System.out.println("Enter some numbers: ");
    try (Scanner scnr = new Scanner(System.in)) {
      do {
        inputs.add(scnr.nextInt());
        System.out.println("Would you like to enter another y/n?");
      } while (scnr.next().equalsIgnoreCase("y"));
    }
    System.out.println(inputs);
  }
}

这将产生以下输出：

Enter some numbers: 
14
Would you like to enter another y/n?
y
15
Would you like to enter another y/n?
y
17
Would you like to enter another y/n?
y
44
Would you like to enter another y/n?
n
[14, 15, 17, 44]

读取数字的另一种方法是从空格分隔的行中读取多个数字：

Answer 2

我认为您过于复杂了。您只需要一个循环，一直运行到用户输入'n'。

在发生这种情况之前，请用户输入数字，将其读入，然后询问他们是否要继续。适当地更新循环条件，就可以完成：

public static void main(String... args) {
    ArrayList<Integer> inputs = new ArrayList<Integer>();
    try (Scanner scnr = new Scanner(System.in)) {
        boolean valid = true;
        while (valid) {
            System.out.println("Enter some numbers: ");
            if (scnr.hasNextInt()) {
                inputs.add(scnr.nextInt());
            }
            System.out.println("Would you like to enter another?");
            String response = scnr.next();
            valid = response.trim().equalsIgnoreCase("y");
        }
    }
    System.out.println(inputs);
}

产生输出

Enter some numbers: 
1
Would you like to enter another?
y
Enter some numbers: 
2
Would you like to enter another?
y
Enter some numbers: 
3
Would you like to enter another?
n
[1, 2, 3]

我如何摆脱这个无限循环，在这个无限循环中，用户说“是”，然后回到第一个while循环，直到用户说“否”？

2 个答案: