if the header like this android:layout_height="wrap_content"

[noties]

if the header like this android:layout_height="wrap_content"

[noties]

@gushoubang Well, try wrapping TextView in a ViewGroup with fixed height or set TextView's height to some dimen. gravity="center" will center text inside TextView.

[xiaogu-space]

Well，I want to use ImageView instead of Textview，but the picture come from the net,I do not know the height.

[noties]

I guess, that simplest solution would be setting fixed height for your ImageView & setting scaleType="centerCrop". That way image would stretch to ImageView's bounds.
But if there is a need for pixel-perfect image displaying I would recommend obtaining a Bitmap & updating ImageView's layoutParams.height & ScrollableLayout.setMaxScrollDistance()