Nullpointer exception when interact

Don't print to see if something is null, use debugging instead. Debugging provides a lot more information.

 

what a detailed and informative post. your explanation of debugging has made me question everything i thought i once knew.

printing an object to see if its null or if its objects are null (depending on how well implemented #toString is) is debugging.. and provides the most information you can get regarding an object being null? i dont know what you think debugging is but printing null is just fine if #toString is fully implemented. if not, you just print the objects subobjects as well

 

I assume he means the more advanced debugging that the development software is capable of. I've never tried that kind of debugging in Java, but when I debug stuff with Visual Studio I can add breakpoints and see the contents of all the variables in memory at a glance and get profiling information and all sorts of other goodies.

 

I would assume that he's referring to using an IDE debugger as well. Depending on the OP's IDE, the steps may be slightly different. However there are a couple pages on the wiki that explain how to do it in both Eclipse and IntelliJ.
https://www.spigotmc.org/wiki/eclipse-debug-your-plugin/
https://www.spigotmc.org/wiki/intellij-debug-your-plugin/

That said though, if they don't want to go through the steps to set it up (as it can be a bit of a hassle to set it up on a live server), or if they simply can't (such as if they don't have a server where they can manage the jar launch settings), then printing to the console would be a solid choice for debugging as an alternative.

 

I mean debugging at runtime, IE adding breakpoints. You can just add a breakpoint without needing to add one or more print statements and it will also tell you a lot more information other than what the variable's value is. It may seem complicated, but it really isn't; IntelliJ provides a pretty simple debugging solution built-in.

You can also perform "hotswaps" which is basically reloading the plugin/application at runtime without needing to issue any commands on the server, as long as no lines were added/removed.