User Input Java

Question

I am building an application in Java (using NetBeans) that accepts user input through the console and prints out a statement using their name (given in user input). The following is the code:

package amazingpets;
import java.io.Console;

public class AmazingPets {

    public static void main(String[] args) {
        Console console = System.console();
        String firstName = console.readLine("What is your name? ");
        console.printf("My name is %s.\n",firstName);
    } 
}

However I keep getting the following error in the console:

Exception in thread "main" java.lang.NullPointerException
at amazingpets.AmazingPets.main(AmazingPets.java:14)
Java Result: 1

Can anyone please suggest a possible solution?

When you post code and an exception with a line number in it, it is a bad idea to reformat the code. The Exception is triggered on line 14. Your posted code has less than 14 lines. Which line is the actual 14? — Erik Vesteraas, May 23 '15 at 21:07

score 2 · Accepted Answer · answered May 23 '15 at 21:10

From the documentation of System#console, it returns:

The system console, if any, otherwise null.

So your code is equivalent to:

String firstName = null.readLine("What is your name? ");

I would suggest you to use Scanner scanner = new Scanner(System.in); instead.

Erik Vesteraas · Answer 2 · 2015-05-23T21:18:34.233

0

When you run code in an IDE you will usually not have a console object. System.console() will thus return null and console.readLine("What is your name? "); will generate a NullPointerException. You can still read via System.in, so to read a line you can instead use:

Scanner sc = new Scanner(System.in);
String read = sc.nextLine();

edited May 23 '15 at 21:18

answered May 23 '15 at 21:09

Erik Vesteraas

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In that case, can you please suggest possible solutions for acquiring Input in the IDE? – MarcB1 May 23 '15 at 21:11
Apparantly `System.in` should still work in NetBeans specifically. So for example `new Scanner(System.in)` should work. – Erik Vesteraas May 23 '15 at 21:15

score 0 · Answer 3 · edited May 23 '17 at 11:58

0

System.console() returns a console if it exists. Java apps may be launched without a console.

Anywhy it seams this is a duplicate of this one (among others):

Why does System.console() return null for a command line app?

Hope it helps

edited May 23 '17 at 11:58

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answered May 23 '15 at 21:10

Leo Nomdedeu

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score 0 · Answer 4 · edited May 23 '17 at 12:15

0

Use Scanner instead of Console
As mentioned in this answer this answer

edited May 23 '17 at 12:15

Community

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answered May 23 '15 at 21:12

Ahd Radwan

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score 0 · Answer 5 · answered May 23 '15 at 21:13

Isn't line 14 where you create firstName variable? In this case console may be null. Javadoc for Console says

` a unique instance of this class which can be obtained by invoking theSystem.console() method. If no console device is available then an invocation of that method will return null.`

User Input Java

5 Answers5