Help Help with code ..

[Re1d]

Hello all,

 

I've been just trying to implement one very simple voice command  on the server pack . 

 

I get no errors during compilation , but when  i run gameserver i get that error at the end.

 

I tried to trace it down but i cant find it..

 

I went on to net.sf.l2j.gameserver.handler.UserCommandHandle and line 45 but it shows no error . 

 

any help would be greatly appreciated.

 

This is the error : 

 

Exception in thread "main" java.lang.ExceptionInInitializerError
        at net.sf.l2j.gameserver.handler.UserCommandHandler.getInstance(UserCommandHandler.java:45)
        at net.sf.l2j.gameserver.GameServer.<init>(GameServer.java:277)
        at net.sf.l2j.gameserver.GameServer.main(GameServer.java:383)
Caused by: java.lang.NullPointerException
        at net.sf.l2j.gameserver.handler.UserCommandHandler.registerUserCommandHandler(UserCommandHandler.java:70)
        at net.sf.l2j.gameserver.handler.UserCommandHandler.<init>(UserCommandHandler.java:51)
        at net.sf.l2j.gameserver.handler.UserCommandHandler$SingletonHolder.<clinit>(UserCommandHandler.java:97)
        ... 3 more

[Rootware]

Need share full code of voice's command handler and what L2J source name you are uses. We can't help you more than told you JVM console.

[SweeTs]

  On 4/12/2019 at 6:22 AM, Re1d said:

Caused by: java.lang.NullPointerException

Expand  

 

[`Sanctus]

https://stackoverflow.com/questions/218384/what-is-a-nullpointerexception-and-how-do-i-fix-it

[Tryskell]

UserCommandHandler.java line 70 ends with a NPE. If it's your new handler, verify if you initialized it correctly.

 

Short version : UserCommandHandler instance can't load properly, because an error (NPE) has been found on line 70 during the registration of an handler.

Edited April 14, 2019 by Tryskell

[Re1d]

thank you all for your answers . 

[murphybeck]

  On 4/12/2019 at 11:07 AM, SweeTs said:

 

Expand  

NullPointerExceptions are exceptions that occur when you try to use a reference that points to no location in memory (null) as though it were referencing an object. Calling a method on a null reference or trying to access a field of a null reference will trigger a NullPointerException. 

 

For example,

 

String s = null;
int len = s.length();  // NullPointerException because s is null

So you should check if the variable is null before calling any method on it, for example:

int len;
if (s == null) {
    len = 0;
}
else {
    len = s.length();  // safe, s is never null when you get here
}

 

How to avoid NullPointerExceptions?

 

• Use the final modifier to enforce good initialization.
• Avoid returning null in methods, for example returning empty collections when applicable.
• Use annotations @NotNull and @Nullable
• Fail fast and use asserts to avoid propagation of null objects through the whole application when they shouldn't be null.
• Use equals with a known object first: if("knownObject".equals(unknownObject)
• Prefer valueOf() over toString().
• Use null safe StringUtils methods StringUtils.isEmpty(null).