android - Why does setting imeActionId with a predefined ID resource create an error?

Question

Cyril Mottier has a great post on customizing the send/done/return key on the Android soft keyboard. When trying out the code, I (and several others in the comments) noticed that setting the imeActionId with a new ID in XML (e.g. @+id/...) returns a 0 to the OnEditorActionListener, when the key is hit by the user, not the unique ID. However, if you set an ID in ids.xml and set imeActionId to that (e.g. w/ @id/...) it causes a layout inflation error.

The only way I could successfully get the imeActionId to be set to a unique ID was to set it programmatically in Java. So what is the correct usage of the XML attribute imeActionId?

Here is a Gist with all of my code: https://gist.github.com/gsysko/d46adbe27d409bde0299

Thanks for considering this question.

Answer 1

The reason is that imeActionId is a slight misnomer in this case. The Javadoc for imeActionId says:

Supply a value for EditorInfo.actionId used when an input method is connected to the text view.

It is looking for you to assign a value. A resource ID is for identifying resources in your app and does not have a guaranteed value. In some cases you can make comparisons based on resource ID's, such as View.getId(), but it is not good to mix resource ID's in with constant values that EditorInfo uses. Android may try to prevent you from doing this when it parses in your XML files by throwing exceptions like you saw, but there's not many checks it can do at runtime if you set it programmatically.

Instead, you can define an integer value in your resources like so:

<!--res/values/integers.xml-->
<resources>
<item type="integer" name="customImeActionId" format="integer">100</item>
</resources>

and use it like

android:imeActionId="@integer/customImeActionId"

In your code you can then retrieve it

int imeActionId = getResources().getInteger(R.integer.customImeActionId);

edit: OK, this has piqued my interest so looking further in the Android source code, TextView parses the attribute like:

mEditor.mInputContentType.imeActionId = a.getInt(attr, mEditor.mInputContentType.imeActionId);

It will use mEditor.mInputContentType.imeActionId as the default value -- which is 0 in this case -- if it can't find the int value of attr, which explains why it returns 0 if you use a newly created ID. I haven't found the cause of the inflation error.