I get this warning in a layout
where I load a RecyclerView
inside the onCreate
on this line specifically in setLayoutManager
recyclerView.setLayoutManager(layoutManager);
generates the following:
Method invocation 'setLayoutManager' may produce 'java.lang.NullPointerException
And to solve this it offers me
assert recyclerView != null;
First of all, I would like to know the reason for the warning and if the solution is effective. I look forward to his ideas. Thanks.
The error tells you that this method can throw the exception
java.lang.NullPointerException
.This exception, as the documentation indicates, occurs because of the following:
Additionally, applications should throw instances of this class to indicate other illegal uses of the null object.
So what it's telling you is that an exception may be thrown in your code in which you try to perform some of the above actions on a null object which could kill your program.
To keep your back and that this does not happen, it offers you a solution. This is for you to protect your code from throwing exceptions that can kill your program. What that code actually means is that you apply the following:
In this way, if the
recyclerView
is null, it will not execute the methodsetLayoutManager
and therefore the exceptionjava.lang.NullPointerException
for this particular case will not be thrown.