Simple Expand / Collapse RecyclerView Item

expand-collapse.java

public static class ExampleViewHolder extends RecyclerView.ViewHolder 
    implements View.OnClickListener {

    private int originalHeight = 0;
    private boolean isViewExpanded = false;
    private YourCustomView yourCustomView
    
    public ExampleViewHolder(View v) {
     super(v);
     v.setOnClickListener(this);

     // Initialize other views, like TextView, ImageView, etc. here

     // If isViewExpanded == false then set the visibility 
     // of whatever will be in the expanded to GONE

     if (isViewExpanded == false) {
         // Set Views to View.GONE and .setEnabled(false)
         yourCustomView.setVisibility(View.GONE);
         yourCustomView.setEnabled(false);
     }
     
    }

    @Override
    public void onClick(final View view) {
        // If the originalHeight is 0 then find the height of the View being used 
        // This would be the height of the cardview
        if (originalHeight == 0) {
                originalHeight = view.getHeight();
            }
    
        // Declare a ValueAnimator object
        ValueAnimator valueAnimator;
            if (!mIsViewExpanded) {
                yourCustomView.setVisibility(View.VISIBLE);
                yourCustomView.setEnabled(true);
                mIsViewExpanded = true;
                valueAnimator = ValueAnimator.ofInt(originalHeight, originalHeight + (int) (originalHeight * 2.0)); // These values in this method can be changed to expand however much you like
            } else {
                mIsViewExpanded = false;
                valueAnimator = ValueAnimator.ofInt(originalHeight + (int) (originalHeight * 2.0), originalHeight);
    
                Animation a = new AlphaAnimation(1.00f, 0.00f); // Fade out
    
                a.setDuration(200);
                // Set a listener to the animation and configure onAnimationEnd
                a.setAnimationListener(new Animation.AnimationListener() {
                    @Override
                    public void onAnimationStart(Animation animation) {
    
                    }
    
                    @Override
                    public void onAnimationEnd(Animation animation) {
                        yourCustomView.setVisibility(View.INVISIBLE);
                        yourCustomView.setEnabled(false);
                    }
    
                    @Override
                    public void onAnimationRepeat(Animation animation) {
    
                    }
                });
    
                // Set the animation on the custom view
                yourCustomView.startAnimation(a);
            }
            valueAnimator.setDuration(200);
            valueAnimator.setInterpolator(new AccelerateDecelerateInterpolator());
            valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
                public void onAnimationUpdate(ValueAnimator animation) {
                    Integer value = (Integer) animation.getAnimatedValue();
                    view.getLayoutParams().height = value.intValue();
                    view.requestLayout();
                }
            });
            valueAnimator.start();
    }
    
}

This code works perfectly, could you please add some more comments explaining why and how it works?