1. How to run the program?
- The program contains multiple .java files, so you'll need to compile all of them first.
- After that, you'll run the TabbedPaneGUI.java. It's a Java application and it will show a GUI for you to play with!

2. How to use the program?
- On the GUI, there will be several tabs at the top, each tab representing a data structure. 
By clicking each tab, you'll switch to a different data structure. 
- On each tab, there will be some buttons on the right, 
and you can click them and follow whatever instructions you are given on the top of the tab,
in order to manipulate the data structure with its given methods. 

3. Some known logical errors?
- Right now, the program works, but the three data structures already implemented do not look very in sync with each other in style.
- In the Graph data structure, the nodes are hard to click sometimes (they don't receive the clicks),
because the way I identify whether a click is in the node is a bit not accurate mathematically. 
Hence, I'll need to improve this. 
- If you click ArrayList before Graph and Array tabs, it shows nothing.
However, if you click Graph, Array, and then ArrayList tabs, everything is fine.
This is a bug that I haven't been able to solve yet.