setLayoutParams on ConstraintLayout does not change size

Question

Story

I have 2 textviews, one on top of another:

XXXXXXXXXXXX[TextView1]
XXXXXXXXXXXX[TextView2]

• Both TextViews aligns to the right. (Hence the XXX above)
• TextView1 has a background color.
• TextView2 is always longer than TextView1
• TextView1's left must be aligned with TextView2

I have the above 4 requirements. Now everything works well by using ConstraintLayout, where TextView1's left is constrained to TextView2's left, and TextView2's width is wrap_content.

But now it comes the 5th requirement:

• TextView2 can disappear, leaving TextView1 behind.

setVisibility(GONE) does not work, because TextView2 must be wrap_content. it will become 0 in width and therefore TextView1 as well (since its left is constrained to TextView2's left)

Then I tried to set TextView2's height to be 0, using the below code:

    ConstraintLayout.LayoutParams lp = (ConstraintLayout.LayoutParams)textView2.getLayoutParams();
    lp.width = widthInPixelOrConstant;
    textView2.setLayoutParams(lp);

Oops, nothing happens. TextView2 remains there, as if nothing happened. I Googled for half an hour, and finally decided to wrap TextView2 in a LinearLayout.

And then using the below code to set height of TextView2 to be 0:

    LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams )view.getLayoutParams();
    lp.width = widthInPixelOrConstant;
    view.setLayoutParams(lp);

......It works!!!

The Question

So, apparently, we cannot use what we used before - setLayoutParams to try to alter the height or width of a ConstraintLayout's child at runtime.
But then, wrapping that TextView2 in a LinearLayout is really stupid.
Does anyone knows how to change a ConstraintLayout's child width or height at runtime?

Answer 1

Try add constraints at runtime, like this:

//Define some variables
TextView textView1;
TextView textView2;
ConstraintLayout constraintLayout;

//Initialize them, and so some stuff
textView1 = (TextView) findViewById(R.id.text1);
textView2 = (TextView) findViewById(R.id.text2);
constraintLayout = (ConstraintLayout) findViewById(R.id.constraintLayout);

int x = 200; //set some width
int y = 200; //Set some height        

ConstraintLayout.LayoutParams lp = new ConstraintLayout.LayoutParams(
            ConstraintLayout.LayoutParams.WRAP_CONTENT,
            ConstraintLayout.LayoutParams.WRAP_CONTENT);

lp.width = x;
lp.height = y;

//moves TextView1's left to align with TextView2's left
lp.editorAbsoluteX = ((int) textView2.getX());     

textView1.setLayoutParams(lp);

ConstraintSet constraintSet = new ConstraintSet();
constraintSet.clone(constraintLayout);        

constraintSet.connect(R.id.text1,ConstraintSet.LEFT,R.id.text2,ConstraintSet.LEFT,0);
constraintSet.connect(R.id.text2,ConstraintSet.TOP,R.id.text1,ConstraintSet.BOTTOM,0);

constraintSet.applyTo(constraintLayout);

I hope that helps!