Difference between getContext() and requireContext() when using fragments

Question

I've been having this doubt since a long time, when I'm working with android fragments and I need to instantiate a Context, or I need to pass a Context as argument for other function, I can choose to use between getContext() and requireContext() methods to achieve that, I normally prefer to use requireContext(), but just because the IDE(Android Studio) shows warnings sometimes when I use the getContext().But the result of using one or other method seems to be the same, no matter what I choose.

My question is, is there any difference between these two methods? If this is the case, which one is better, or which should I use in each case?

Solution 1

getContext() returns a nullable Context.

requireContext() returns a nonnull Context, or throws an exception when one isn't available.

If your code is in a lifecycle phase where you know your fragment is attached to a context, just use requireContext() to get a Context and also keep static analyzers happy about potential NPE issues.

If your code is outside of regular fragment lifecycle (say, an async callback), you might be better off using getContext(), checking its return value yourself and only proceeding using it if it was non-null.

Being explicit with nullability is even more important in Kotlin where it is built into the language's type system.

Solution 2

While Laalto's answer is correct, I'm adding the code to prove the difference between requireContext() and getContext.

In Fragment.java you should see the following code.

@NonNull
    public final Context requireContext() {
        Context context = getContext();
        if (context == null) {
            throw new IllegalStateException("Fragment " + this + " not attached to a context.");
        }
        return context;
    }

You can see that the requireContext() method throws an exception when the context is null.

@Nullable
    public Context getContext() {
        return mHost == null ? null : mHost.getContext();
    }

On the other hand, If you see the code for getContext(), there is a chance that you might get a null value when called.