when I copy code from this tutorial , everythink works correctly. But when I change the model from example to my, which I made in Blender, it writes error java.lang.NullPointerException. It is because of:  control.addListener(this);   And it is because "control" is null. And it is because previous instruction:   control = player.getControl(AnimControl.class);    gives null to variable "control".  So what is the solution? When I try example code from tutorial, it works correctly, but when I replace the model name(path), it doesn't works. (Path of model is correct, because when I only display my model, it load the model correctly).
What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?
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