types cannot be converted when validating the users input for an integer

I am trying to validate a user's input and check if the inputted number is an integer. Id like to throw them an error message if the number isn't an integer. I am getting stuck on the line Integer.parseInt(number); Any suggestions would be very appreciated.

import java.util.Scanner;

public class Sums {

    public static int number;

    public static void main(String[] args) {
        int evenSum, oddSum = 0;
        int posInt;
        Scanner input = new Scanner(System.in);
        System.out.println("Enter a postitive integer: ");
        int number = input.nextInt();
        try {
            Integer.parseInt(number);
            System.out.println("Value entered is " + number);
        } catch (NumberFormatException e) {
            System.out.println(number + " is not an integer.");
        }
    }
}

You don't need explicitly to convert your number to an integer, Scanner.nextInt() already does that for you, i.e. Scanner.nextInt() scans the next token of the input as an int. So just remove the line "int number = input.nextInt();" from your code. In general, Integer.parseInt() is preferable when you want to convert a String representation of an Integer value as a signed decimal integer. For instance, if you would have used Scanner.nextLine() instead of Scanner.nextInt(), then it makes more sense to convert it to a signed decimal integer if you want to perform subsequent operations using that integer value.

The issue here is that when you call Integer.parseInt(number) you are trying to parse the variable number which is an int and not a String. This means that you are doing the error checking on a conversion from an int to an Integer and not a String to an Integer.

To fix this, input a string instead of a number, then perform the conversion on the string, not the number.

...

public static void main(String[] args) {
    int myNumber;
    Scanner input = new Scanner(System.in);
    System.out.println("Enter a postitive integer: ");
    String numberString = input.nextLine();
    try {
        myNumber = Integer.parseInt(number);
        System.out.println("Value entered is " + myNumber);

        // do what you want with the number

    } catch (NumberFormatException e) {
        System.out.println(numberString + " is not an integer.");
    }
}

...

I have changed the int number = input.nextInt(); to String number = input.next(); and it works.

int number = input.nextInt();

The variable <b>number</b> is already an int, that is why you can not hand it over to the method. The method requires a String.

If you want to use the method like you did, you should use

input.next()

as argument because it returns the input as String and initialize number within the try block, e.g.

      public static void main(String[] args) {
        int evenSum, oddSum = 0;
        int posInt;
        System.out.println("Enter a postitive integer: ");
        Scanner input = new Scanner(System.in);
        try {
            number = Integer.parseInt(input.next());
            System.out.println("Value entered is " + number);
        } catch (NumberFormatException e) {
            System.out.println("Not an integer.");
        }
    }

Bug here is int number = input.nextInt();<br>

When you want to convert a String to a primitive datatype we use class.parseXXX(String)<br>
You see I have written String in the function .parseXXX(String) Cause it takes String as a parameter and nothing else<br>
So lets read your code

Integer.parseInt(number);

Here its .parseXXX(int) and clearly its not matching .parseXXX(String)<br>
So in order to give String as parameter, you have accept String as input from user.<br>

Replace this int number = input.nextInt(); with String number = input.next();

So now below code is valid cause its in .parseXXX(String)

Integer.parseInt(number);

Changed code:

        int evenSum, oddSum = 0;
        int posInt;
        Scanner input = new Scanner(System.in);
        System.out.println("Enter a postitive integer: ");
        String number = input.next(); // <-- Changed
        try {
            Integer.parseInt(number);
            System.out.println("Value entered is " + number);
        } catch (NumberFormatException e) {
            System.out.println(number + " is not an integer.");
        }