redp | A simple desktop cross-platform music player | Dektop Application library

The problem is that you are accessing the same value (this.state.changePlanet) 3 times and expecting a different result. I think you just need to make the method return a random planet like so:

According to the documentation for array_walk_recursive, "any key that holds an array will not be passed to the function".

Write a recursive function instead which adds the value to a subelement if it is an array. For example:

MPAndroidChart cannot shield you from the effects of not separating model and view layers and from issues with the managing the lifecycles of Fragments and Activities. Please note that "communicating" between Fragments (such as one Fragment manipulating the data of another) is not recommended by Google:

Two Fragments should never communicate directly

Although Entry may look like a member of the model layer, it is actually designed to be tightly coupled with PieChart which is part of the view layer. It definitely should not outlive the View with which it is associated and if you want to avoid errors such as the ArrayIndexOutOfBoundsException, the backing List lifecycle should coincide with that of the Fragment in which it is used. This does not mean that you can never add/remove from a List once this is part of a PieChart - MPAndroidChart will allow you to do this within the above constraints.

To fix the above error, I would suggest a different approach than sharing a static object which is almost never a good idea in Android. You could share, instead, a separate model layer which contains the data you will use to construct the List. When Fragment A updates the model, you can use an event to trigger rebuilding of the chart from the data inside Fragment B.

You have stated in the comments that you are using a ViewPager. The ViewPager uses fragmentTransaction.show() and .hide() and generally keeps the Fragments in a resumed state. Perhaps the easiest solution is to override onHiddenChanged as this is always called when the ViewPager switches to a new page. I think (not 100% sure) that you will also need a call in onActivityCreated(View v).

So, you would have something like this: