How can I know if I need to call setLayoutParams or just change the values of existing LayoutParams?

Question

How can I know if getLayotParams() return a reference to the effective params or it's just a deep copy of the params?

say:

MarginLayoutParams layoutParams = (MarginLayoutParams) getView().getLayoutParams();

layoutParams.leftMargin = horizontalMargin;
layoutParams.rightMargin = horizontalMargin;

is enough, or this line is needed as well?

parent.setLayoutParams(layoutParams);

score 0 · Accepted Answer · answered May 16 '20 at 20:45

0

getLayoutParams returns the actual LayoutParams, not a deep copy. However, updating the parameters won't trigger a layout, you would have to call requestLayout, which is automatically called when you use setLayoutParams.

So if you want to modify the values and have them applied, you need to either call setLayoutParams or trigger a layout with requestLayout.

If you use Kotlin, you can use the updateLayoutParams extension function as well.

answered May 16 '20 at 20:45

Francesc

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Thanks, how can I see that if you hadn't told me? – Elad Benda May 16 '20 at 20:50
You can check the source code for the View class and check the `getLayoutParams` method. – Francesc May 16 '20 at 20:55

How can I know if I need to call setLayoutParams or just change the values of existing LayoutParams?

1 Answers1