What is the ID of the back arrow drawable in the ActionBar?

问题

The following code causes a back arrow to appear in the ActionBar:

getSupportActionBar().setDisplayShowHomeEnabled(true);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);

I'm looking for the resource ID of the arrow drawable, i.e. android.R.drawable.xxx. The reason I need this ID is so that I can manually set an identical arrow (size & colour) elsewhere in my app.

I tried making my own drawable and using that but the size was different from the one in the ActionBar.

回答1:

If you have the support library in your project, you can make a back button in any place in your applicaction like this:

<ImageButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="?attr/homeAsUpIndicator"
        android:background="?attr/selectableItemBackgroundBorderless"/>

Specifically the resource for the back arrow is ?attr/homeAsUpIndicator.

回答2:

The id of the back button in Toolbar is

android.R.id.home

You can take action from onOptionsItemSelected Method on Activity.

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    if (item.getItemId() == android.R.id.home) {
        //Do your task here.
        return true;
    }
    return super.onOptionsItemSelected(item);
}

来源：https://stackoverflow.com/questions/44807847/what-is-the-id-of-the-back-arrow-drawable-in-the-actionbar