Ethan Allen Ethan Allen - 1 year ago 119
Java Question

How do I tell if Intent extras exist in Android?

I have this code that checks for a value of an extra in an Intent on an Activity that is called from many places in my app:


If isNewItem isn't set, will my code crash? Is there any way to tell if it's been set or not before I call it?

What is the proper way to handle this?

Answer Source

As others have said, both getIntent() and getExtras() may return null. Because of this, you don't want to chain the calls together, otherwise you might end up calling null.getBoolean("isNewItem"); which will throw a NullPointerException and cause your application to crash.

Here's how I would accomplish this. I think it's formatted in the nicest way and is very easily understood by someone else who might be reading your code.

// You can be pretty confident that the intent will not be null here.
Intent intent = getIntent();

// Get the extras (if there are any)
Bundle extras = intent.getExtras();
if (extras != null) {
    if (extras.containsKey("isNewItem")) {
        boolean isNew = extras.getBoolean("isNewItem", false);

        // TODO: Do something with the value of isNew.

You don't actually need the call to hasExtra("isNewItem") as getBoolean("isNewItem", false) will return false if the extra does not exist. You could condense the above to something like this:

Bundle extras = getIntent().getExtras();
if (extras != null) {
    boolean isNew = extras.getBoolean("isNewItem", false);
    if (isNew) {
        // Do something
    } else {
        // Do something else

You can also use the Intent methods to access your extras directly. This is probably the cleanest way to do so:

boolean isNew = getIntent().getBooleanExtra("isNewItem", false);

Really any of the methods here are acceptable. Pick one that makes sense to you and do it that way.

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