Modification in TreeView App

I have a working code for a TreeView and I need a modification in the app. I want that if the item in the view is not expandable then when clicking on it starts a new activity. as shown in the attached screen. If Grandchild is clicked a new activity should open. If Child 1 ( which is non-expandable) is clicked a new activity should be opened and if Parent 3 ( which is non-expandable) is clicked a new activity should be opened. Code will be provided after the acceptance of the project. Happy Coding :)