Android: Expand/collapse animation

Question

Let\'s say I have a vertical linearLayout with :

[v1]
[v2]

By default v1 has visibily = GONE. I would like to show v1 with an expand animat

Answer 1

Best solution for expand/collapse view's:

    @Override
    public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
        View view = buttonView.getId() == R.id.tb_search ? fSearch : layoutSettings;
        transform(view, 200, isChecked
            ? ViewGroup.LayoutParams.WRAP_CONTENT
            : 0);
    }

    public static void transform(final View v, int duration, int targetHeight) {
        int prevHeight  = v.getHeight();
        v.setVisibility(View.VISIBLE);
        ValueAnimator animator;
        if (targetHeight == ViewGroup.LayoutParams.WRAP_CONTENT) {
            v.measure(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
            animator = ValueAnimator.ofInt(prevHeight, v.getMeasuredHeight());
        } else {
            animator = ValueAnimator.ofInt(prevHeight, targetHeight);
        }
        animator.addUpdateListener(animation -> {
            v.getLayoutParams().height = (animation.getAnimatedFraction() == 1.0f)
                    ? targetHeight
                    : (int) animation.getAnimatedValue();
            v.requestLayout();
        });
        animator.setInterpolator(new LinearInterpolator());
        animator.setDuration(duration);
        animator.start();
    }