Scanner error with nextInt()

Question

I am trying to use Scanner to get an int from the keyboard, but I getting the following error: ``` Exception in thread "main" java.util.NoSuchElementException at java.util.Scanner.throwFor(Scanner.java:907) at java.util.Scanner.next(Scanner.java:1530) at java.util.Scanner.nextInt(Scanner.java:2160) at java.util.Scanner.nextInt(Scanner.java:2119) at TableReader.mainMenu(TableReader.java:122) at TableReader.main(TableReader.java:76) ``` This is what I have. It is independent of the rest of my program, I don't understand why this isn't working. It is declared in a method that is being called in a while loop, if that helps. ``` // scan for selection Scanner s = new Scanner(System.in); int choice = s.nextInt(); // error occurs at this line s.close(); ``` I stepped through with the debugger and narrowed the error down to: A fatal error has been detected by the Java Runtime Environment: SIGSEGV (0xb) at pc=0xb6bdc8a8, pid=5587, tid=1828186944 JRE version: 7.0_07-b30 Java VM: OpenJDK Server V…

Accepted Answer

You should use the `hasNextXXXX()` methods from the `Scanner` class to make sure that there is an integer ready to be read.

The problem is you are called `nextInt()` which reads the next integer from the stream that the `Scanner` object points to, if there is no integer there to read (i.e. if the input is exhausted then you will see that `NoSuchElementException`)

From the JavaDocs, the `nextInt()` method will throw these exceptions under these conditions:

- InputMismatchException - if the next token does not match the Integer regular expression, or is out of range

- NoSuchElementException - if input is exhausted

- IllegalStateException - if this scanner is closed

You can fix this easily using the `hasNextInt()` method:

```
Scanner s = new Scanner(System.in);
int choice = 0;

if(s.hasNextInt()) 
{
   choice = s.nextInt();
}

s.close();
```

Scanner error with nextInt()

Solution

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