Right way to use the @NonNull annotation in Android Studio

Question

I\'d like to use the @NonNull annotation in Android, but I can\'t figure out just the right way to do it. I propose you this example:

public voi         


        

Answer 1

Google examples do it as follows

import static com.google.common.base.Preconditions.checkNotNull;

...

public void doStuff(@NonNull String sParm){
     this.sParm= checkNotNull(s, "sParm cannot be null!");
}

Answer 2

You can use the comment-style suppression to disable that specific null check warning, e.g.:

    public MyMethod(@NonNull Context pContext) {
        //noinspection ConstantConditions
        if (pContext == null) {
            throw new IllegalArgumentException();
        }
        ...
    }

You'll need that //noinspection ConstantConditions every time you do it.

Answer 3

You can use Objects.requireNonNull for that. It will do the check internally (so the IDE will not show a warning on your function) and raise a NullPointerException when the parameter is null:

public MyMethod(@NonNull Context pContext) {
    Objects.requireNonNull(pContext);
    ...
}

If you want to throw another exception or use API level < 19, then you can just make your own helper-class to implement the same check. e.g.

public class Check {
    public static <T> T requireNonNull(T obj) {
        if (obj == null)
            throw new IllegalArgumentException();
        return obj;
    }
}

and use it like so:

public MyMethod(@NonNull Context pContext) {
    Check.requireNonNull(pContext);
    ...
}