Java Scanner ioException() Method

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Description

The java.Scanner ioException() method returns the IOException last thrown by this Scanner's underlying Readable. This method returns null if no such exception exists.

Declaration

Following is the declaration for java.util.Scanner.ioException() method

public IOException ioException()

Parameters

NA

Return Value

This method returns the last exception thrown by this scanner's readable

Exception

NA

Checking ioException Using Scanner on a String Example

The following example shows the usage of Java Scanner ioException() method to check IOException last thrown by this Scanner's underlying Readable. We've created a scanner object using a given string. Then we printed the string using nextLine() method and then exception if any is printed. Scanner is closed using close() method.

package com.tutorialspoint;

import java.util.Scanner;

public class ScannerDemo {
   public static void main(String[] args) {

      String s = "Hello World! 3 + 3.0 = 6";

      // create a new scanner with the specified String Object
      Scanner scanner = new Scanner(s);

      // print the next line of the string
      System.out.println(scanner.nextLine());
      
      System.out.println(scanner.ioException());
      // close the scanner
      scanner.close();

   }
}

Output

Let us compile and run the above program, this will produce the following result −

Hello World! 3 + 3.0 = 6
null

Checking ioException Using Scanner on User Input Example

The following example shows the usage of Java Scanner ioException() method to check IOException last thrown by this Scanner's underlying Readable. We've created a scanner object using System.in class. Then we printed the string using nextLine() method and then exception if any is printed. Then scanner is closed using close() method.

package com.tutorialspoint;

import java.util.Scanner;

public class ScannerDemo {
   public static void main(String[] args) {

      // create a new scanner with the system input
      Scanner scanner = new Scanner(System.in);

      // print the next line of the string
      System.out.println(scanner.nextLine());

      System.out.println(scanner.ioException());
      // close the scanner
      scanner.close();
   }
}

Output

Let us compile and run the above program, this will produce the following result − (where we've entered Hello World and pressed enter key.)

Hello World
Hello World
null

Checking ioException Using Scanner on a Properties File Example

The following example shows the usage of Java Scanner ioException() method to check IOException last thrown by this Scanner's underlying Readable. We've created a scanner object using a File properties.txt. Then we printed the content using nextLine() method and then exception if any is printed. Then scanner is closed using close() method.

package com.tutorialspoint;

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

public class ScannerDemo {
   public static void main(String[] args) throws FileNotFoundException {

      // create a new scanner with a file as input
      Scanner scanner = new Scanner(new File("properties.txt"));

      // print the next line of the string
      System.out.println(scanner.nextLine());

      System.out.println(scanner.ioException());
      // close the scanner
      scanner.close();
   }
}

Assuming we have a file properties.txt available in your CLASSPATH, with the following content. This file will be used as an input for our example program −

Height=200
Width=15

Output

Let us compile and run the above program, this will produce the following result −.

Height=200
null