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Java

Posted by <noob />
<noob />
17,062 Points

Why i cant run this code in inteliji?

Hi, I have troubles with inteliji..

import java.io.Console;

public class CheckPassFail {

    public static void main(String[] args) {
        Console console = System.console();
        String userInput = console.readLine("Please enter a number : ");
        int number = Integer.parseInt(userInput);
        if (number % 2 == 0) {
            System.out.printf("%d is an even number !", number);
        }
        else {
            System.out.printf("%d is a odd number!", number);
        }

        System.out.printf("Good bye!");


    }
}

when i try to run this program i get nullPointerException

Tonnie Fanadez

1 Answer

Brendan Whiting
seal-mask
.a{fill-rule:evenodd;}techdegree seal-36
Brendan Whiting
Front End Web Development Techdegree Graduate 84,738 Points
Brendan Whiting
.a{fill-rule:evenodd;}techdegree seal-36
Brendan Whiting
Front End Web Development Techdegree Graduate 84,738 Points

I get a NullPointerException too, specifically on this line:

 String userInput = console.readLine("Please enter a number : ");

So this means it's trying to do something but unexpectedly got a null value. I'm guessing that the console object is the null value, so I added this line to print it out, and it is in fact null (could have also used the debugger in IntelliJ).

Console console = System.console();
System.out.println(console); // null
String userInput = console.readLine("Please enter a number : ");

I googled "java.io.Console null pointer exception" and found this StackOverflow article which led me to this blog post about an issue with this console package and IDE's.

But those solutions looked a bit overly complicated to me, and there are other ways of getting input from the command line. I like the Scanner class, myself:

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Please enter a number: ");
        String userInput = scanner.nextLine();
        int number = Integer.parseInt(userInput);
        if (number % 2 == 0) {
            System.out.printf("%d is an even number !", number);
        }
        else {
            System.out.printf("%d is a odd number!", number);
        }
        System.out.printf("Good bye!");
    }
}