Question

我的应用程序有一个循环，重复相同的选择，直到被告知退出。

Scanner scan = new Scanner(System.in);
while(running == true){
  System.out.println("Select an option (1-4):");
  System.out.println("1: Add an item to your store");
  System.out.println("2: Search for an item in your store");
  System.out.println("3: Remove an item from your store");
  System.out.println("4: Buy an item from the store:");
  System.out.println("5: Exit this application");
  int option = scan.nextInt();
  if(option == ... etc.
}

在循环的第二次迭代中，插入的整数不会被接受并返回以下错误：

线程“main”中的异常java.util.InputMismatchException at java.util.Scanner.throwFor（Scanner.java:864）at java.util.Scanner.next（Scanner.java:1485）at java.util.Scanner.nextInt（Scanner.java:2117）at java.util.Scanner.nextInt（Scanner.java:2076）at storeproject.StoreProject.main（StoreProject.java:27）

Answer 1

你得到这个InputMismatchException，因为你的输入不是数字，可能是非数字数据，也可能不是整数，因为你试图得到nextInt()。希望它能帮到你！

Answer 2

我想我知道发生了什么。

下一个int需要有一个数字而且只有一个数字。输入之前或之后的任何非整数值，alpha和标点符号都会给出错误。我试了一下：

<强>代码：

public class ScannerTest {

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        while(true){
            System.out.println("Select an option (1-4):");
            System.out.println("1: Add an item to your store");
            System.out.println("2: Search for an item in your store");
            System.out.println("3: Remove an item from your store");
            System.out.println("4: Buy an item from the store:");
            System.out.println("5: Exit this application");
            int option = scan.nextInt();
            System.out.println(option);
        }
    }
}

<强>输出：

5
5
Select an option (1-4):
1: Add an item to your store
2: Search for an item in your store
3: Remove an item from your store
4: Buy an item from the store:
5: Exit this application
6
6
Select an option (1-4):
1: Add an item to your store
2: Search for an item in your store
3: Remove an item from your store
4: Buy an item from the store:
5: Exit this application
5.
Exception in thread "main" java.util.InputMismatchException
    at java.util.Scanner.throwFor(Scanner.java:864)
    at java.util.Scanner.next(Scanner.java:1485)
    at java.util.Scanner.nextInt(Scanner.java:2117)
    at java.util.Scanner.nextInt(Scanner.java:2076)
    at ScannerTest.main(ScannerTest.java:17)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)

Process finished with exit code 1

Answer 3

尝试

while (scan.hasNextInt() && running)

Java - Scanner在循环后无法读取整数？

3 个答案: