EDIT: This solution is no longer needed. bug fixed in v22.2.1
I didnt want to just leave links so here is the full solution.
The bug occurs because the code to handle the collapsable title only updates the actual title if the current title is null or the text size has changed. The workaround is to change the title text size and then change it back. I used 0.5 sp so there was not too much of a jump. Changing the text size forces the text to be updated and there is no flicker. just a slight text size change.
This is what I have
private void setCollapsingToolbarLayoutTitle(String title) {
mCollapsingToolbarLayout.setTitle(title);
mCollapsingToolbarLayout.setExpandedTitleTextAppearance(R.style.ExpandedAppBar);
mCollapsingToolbarLayout.setCollapsedTitleTextAppearance(R.style.CollapsedAppBar);
mCollapsingToolbarLayout.setExpandedTitleTextAppearance(R.style.ExpandedAppBarPlus1);
mCollapsingToolbarLayout.setCollapsedTitleTextAppearance(R.style.CollapsedAppBarPlus1);
}
in styles.xml I have
<style name="ExpandedAppBar" parent="@android:style/TextAppearance.Medium">
<item name="android:textSize">28sp</item>
<item name="android:textColor">#000</item>
<item name="android:textStyle">bold</item>
</style>
<style name="CollapsedAppBar" parent="@android:style/TextAppearance.Medium">
<item name="android:textSize">24sp</item>
<item name="android:textColor">@color/white</item>
<item name="android:textStyle">normal</item>
</style>
<style name="ExpandedAppBarPlus1" parent="@android:style/TextAppearance.Medium">
<item name="android:textSize">28.5sp</item>
<item name="android:textColor">#000</item>
<item name="android:textStyle">bold</item>
</style>
<style name="CollapsedAppBarPlus1" parent="@android:style/TextAppearance.Medium">
<item name="android:textSize">24.5sp</item>
<item name="android:textColor">@color/white</item>
<item name="android:textStyle">normal</item>
</style>