Button to update layout_weight doesn't take effect

Question

I am using this code in kotlin to update the layout_weight of a linear_layout as an indication. When the button is pressed though, the layout weight doesn't change.

This will eventually be a fun app using random updates but for now I want to make sure that the code works. predWt is the button id physWt is the linearlayout id (currently set with weight 0.3)

        predWt.setOnClickListener {
        physWt.layoutParams.apply {
            (this as LinearLayout.LayoutParams).weight = 0.85f }
        }

The app launches OK and when the button is pressed the layout_weight of the linearlayout should update to 0.85f from 0.3 but does not. There are no error messages generated.

score 0 · Answer 1 · answered Jul 25 '19 at 15:35

0

You need to call setLayoutParams to let the change take effect:

    predWt.setOnClickListener {
    physWt.layoutParams.apply {
        (this as LinearLayout.LayoutParams).weight = 0.85f }
        physWt.setLayoutParams(this)
    }

The reason for this is that the view and its parent view does not know you modified the layout params, by setting it again, View.requestLayout() is called for you

answered Jul 25 '19 at 15:35

ssynhtn

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Using the physWt.setLayoutParams(this) as suggested produced an error of wrong inferred type but using physWt.requestLayout() worked. I only mention this for anyone with a similar problem. If I misunderstood your answer, my apologies. – edwind Jul 26 '19 at 09:39
Any improvements would be gratefully received. I am new to coding and appreciate all help. Thank you for your advice. – edwind Jul 29 '19 at 08:33

Button to update layout_weight doesn't take effect

1 Answers1