[java] Android adding simple animations while setvisibility(view.Gone)

Based on the answer of @Xaver Kapeller I figured out a way to create scroll animation when new views appear on the screen (and also animation to hide them).

It goes from this state:

• Button
• Last Button

to

• Button
• Button 1
• Button 2
• Button 3
• Button 4
• Last Button

and viceversa.

So, when the user clicks on the first button, the elements "Button 1", "Button 2", "Button 3" and "Button 4" will appear using fade animation and the element "Last Button" will move down till end. The height of the layout will change as well, allowing using scroll view properly.

This is the code to show elements with animation:

private void showElements() {
    // Precondition
    if (areElementsVisible()) {
        Log.w(TAG, "The view is already visible. Nothing to do here");
        return;
    }

    // Animate the hidden linear layout as visible and set
    // the alpha as 0.0. Otherwise the animation won't be shown
    mHiddenLinearLayout.setVisibility(View.VISIBLE);
    mHiddenLinearLayout.setAlpha(0.0f);
    mHiddenLinearLayout
            .animate()
            .setDuration(ANIMATION_TRANSITION_TIME)
            .alpha(1.0f)
            .setListener(new AnimatorListenerAdapter() {
                @Override
                public void onAnimationEnd(Animator animation) {
                    super.onAnimationEnd(animation);
                    updateShowElementsButton();
                    mHiddenLinearLayout.animate().setListener(null);
                }
            })
    ;

    mLastButton
            .animate()
            .setDuration(ANIMATION_TRANSITION_TIME)
            .translationY(mHiddenLinearLayoutHeight);

    // Update the high of all the elements relativeLayout
    LayoutParams layoutParams = mAllElementsRelativeLayout.getLayoutParams();

    // TODO: Add vertical margins
    layoutParams.height = mLastButton.getHeight() + mHiddenLinearLayoutHeight;
}

and this is the code to hide elements of the animation:

private void hideElements() {
    // Precondition
    if (!areElementsVisible()) {
        Log.w(TAG, "The view is already non-visible. Nothing to do here");
        return;
    }

    // Animate the hidden linear layout as visible and set
    mHiddenLinearLayout
            .animate()
            .setDuration(ANIMATION_TRANSITION_TIME)
            .alpha(0.0f)
            .setListener(new AnimatorListenerAdapter() {
                @Override
                public void onAnimationEnd(Animator animation) {
                    Log.v(TAG, "Animation ended. Set the view as gone");
                    super.onAnimationEnd(animation);
                    mHiddenLinearLayout.setVisibility(View.GONE);
                    // Hack: Remove the listener. So it won't be executed when
                    // any other animation on this view is executed
                    mHiddenLinearLayout.animate().setListener(null);
                    updateShowElementsButton();
                }
            })
    ;

    mLastButton
            .animate()
            .setDuration(ANIMATION_TRANSITION_TIME)
            .translationY(0);

    // Update the high of all the elements relativeLayout
    LayoutParams layoutParams = mAllElementsRelativeLayout.getLayoutParams();

    // TODO: Add vertical margins
    layoutParams.height = mLastButton.getHeight();
}

Note there is a simple hack on the method to hide the animation. On the animation listener mHiddenLinearLayout, I had to remove the listener itself by using:

mHiddenLinearLayout.animate().setListener(null);

This is because once an animation listener is attached to an view, the next time when any animation is executed in this view, the listener will be executed as well. This might be a bug in the animation listener.

The source code of the project is on GitHub: https://github.com/jiahaoliuliu/ViewsAnimated

Happy coding!

Update: For any listener attached to the views, it should be removed after the animation ends. This is done by using

view.animate().setListener(null);