android-获取以编程方式创建的视图的估计高度

Question

How to get programmatically created RelativeLayout's height after adding all the views in it (ie, when it really can be measured)? I programmatically created Buttons that should be children for that RL, set their margins and alignment, added them to the RL, so RL's height can be measured. Ordinary rl.getHeight() returns 0. I used this code:

rl.measure(View.MeasureSpec.UNSPECIFIED, View.MeasureSpec.UNSPECIFIED); 
int rlHeight=rl.getMeasuredHeight();

And on Nexus 5 (API 23) everything's ok, but on the other device with API 17 (as I remember, 4.2 or something) it throws NPE. What to do?

PS OnGlobalLayoutListener and OnPreDrawListener are not ok, because I need the height to be measured before calling setParams(...) and adding the RL to outer layout.

Answer 1

You can use a GlobalLayoutListener or an OnPreDrawListener to programmatically find a views height at runtime. Refer to this answer for an example: https://stackoverflow.com/a/6569243/4898635

Make sure to remove the listener after you have your height however, otherwise it will continuously be called.