java.lang.IllegalStateException in Java

In this Program I am going to read 1 to n numbers in Java.

Error Message: java.lang.IllegalStateException

Error Description:

In this program actually we have to give numbers as input,but i gave string as input so i got an error.  

package com.lib;

import java.util.Scanner;

public class Print1toN

{

       public static void main(String[] args)

       {

      

              Scanner num = new Scanner(System.in);

              System.out.println("enter n value:");

              //during run time i have given string input, so we will get run time error here.

              int n = num.nextInt();

              for(double a=1.0;a<=n;a++)

              {

                     System.out.println(a);

              }num.close();

       }

}

Error Solution:

package com.lib;

import java.util.Scanner;

public class Print1toN

{

       public static void main(String[] args)

       {

      

              Scanner num = new Scanner(System.in);

              System.out.println("enter n value:");

              //during run time i have given string input, so we will get run time error here.

              int n = num.nextInt();

              for(double a=1.0;a<=n;a++)

              {

                     System.out.println(a);

              }num.close();

       }

}

Output:

enter n value:

5

1.0

2.0

3.0

4.0

5.0