Netbeans IDE 6.1 Compilation fail

[john smith]

The below program in Netbeans IDE compiles fine, but it does not want to run. It gives a NullPointerException. I'm very confused. Advice would be much appreciated. Thanks in advnce.



*****************************Program Start**********

package javaapplication2;
import java.io.*;
public class MyConsole {
static String name;
public static void main(String[] args){
Console c = System.console();
name = c.readLine("Name?");
System.out.println(name);
}
}

*****************************Program End**********




*****************************Netbeans Message Start**********

init:
deps-jar:
compile-single:
run-single:
Exception in thread "main" java.lang.NullPointerException
at javaapplication2.MyConsole.main(MyConsole.java:20)
Java Result: 1
BUILD SUCCESSFUL (total time: 0 seconds)

*****************************Netbeans Message End**********

[Joanne Neal]

The error message says the NPE is happening on line 20 of MyConsole.java, but there only appears to be 10 lines in the file. If you removed blank lines/comments from the file before posting it, can you tell us which is line 20 ?

Edit - having just read the javadoc for the Console class, it's probably due to you running the program from Netbeans. Try running it from a command line and it should work okay.
[ September 01, 2008: Message edited by: Joanne Neal ]

[john smith]

I've done a new compile, copy and paste. The Exception points to:

name = c.readLine("Name?");


******Program start******

package javaapplication2;
import java.io.*;
public class MyConsole {
static String name;
public static void main(String[] args){
Console c = System.console();
name = c.readLine("Name?");
System.out.println(name);
}
}




init:
deps-jar:
compile-single:
run-single:
Exception in thread "main" java.lang.NullPointerException
at javaapplication2.MyConsole.main(MyConsole.java:7)
Java Result: 1
BUILD SUCCESSFUL (total time: 0 seconds)

[Ove Lindström]

Netbeans does not expose it's internal Console to the JVM. If you want to use the Console, you have to run it outside of the IDE.

The line:

Console c = System.console();

assigns null to c since the JVM does not have any console registered to it.