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    CIS 120 Game Project README
    PennKey: zhangall
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    ===================
    =: Core Concepts :=
    ===================
    
    - List the four core concepts, the features they implement, and why each feature
      is an appropriate use of the concept. Incorporate the feedback you got after
      submitting your proposal.
    
      1. 2D Array: I am using a 2D array to represent the game state of the board. This makes
      sense because Connect 4 is played on a vertical board that looks like a grid.
    
      2. Modeling state using a collection: I am using a LinkedList to model the state of the
      move history. This linked list tracks the player and the coordinates of their move in a String.
      This makes sense because order matters, and a LinkedList works by appending something to the
      end of it. Also, none of the entries can be identical because two pieces can never be in the 
      same place.
    
      3. JUnit testable: I am using this to test my Connect 4 game separately from the GUI and the 
      actual game file. This is useful in my case because Connect 4 does not need a GUI to run, and 
      can be played by hard coding it. I can use this aspect of the game to test for wins and other
      things that may happen in the game.
    
      4. File I/O: I am using this to create a leader board of winners and fewest total moves. I
      can read from a file the previous game's leader board, insert the most recent game into the 
      leader board, display it on the game, and overwrite it back into the file.
    
    =========================
    =: Your Implementation :=
    =========================
    
    - Provide an overview of each of the classes in your code, and what their
      function is in the overall game.
    
    Board.java is the JPanel that has the board and is what the user will interact with. It also creates
    an instance of LeaderBoard.java and runs it, because Board.java is the only class that has access to
    the method that checks if the game is over and implements end-of-game functionalities.
    
    Connect4.java sets up the state for the board and move history, and has all the methods for playing a turn, 
    checking for wins, and undoing moves. This is the class that I test in GameTest.java.
    
    Game.java has the runnable method and paints the rest of the GUI, aside from the board itself. 
    
    LeaderBoard.java is like Board.java except it is working on creating the leader board. It has the reader
    and writer. It reads in from the file leaderBoard.txt and moves that information into a TreeMap. This map
    stores the names and # of moves their game had. The TreeMap is able to sort the information. The writer 
    adds a new entry into the TreeMap, removes pairings from the TreeMap in order, and overwrites them into 
    the original .txt file. It also stores the new top 3 into a String array, however I couldn't get this part
    to work. 
    
    - Were there any significant stumbling blocks while you were implementing your
      game (related to your design, or otherwise)?
      
    I couldn't find a way to address when the column gets full. Due to the way I was checking for the row
    to place the piece, I couldn't handle negative row indices effectively. If I had made the play turn 
    method return a boolean, I could've better handled illegal moves.
    
    I also struggled with displaying the leader board. While I could see in my leaderBoard.txt file that 
    my reader and writer were accurately storing and sorting high scores, I couldn't get the values to display
    on my actual game. Thus, when you click on the leader board button after a game, it'll just have null entries.
    I hoped to show my reader and writer worked through tests, but I couldn't think of a good way to do so.
    
    - Evaluate your design. Is there a good separation of functionality? How well is
      private state encapsulated? What would you refactor, if given the chance?
      
      I think I did a good job separating the game itself from the display, however I wish I had better 
      separated the leader board functionalities from the game board. If I could find a way to alert my 
      leader board code that the game was over, instead of relying on Board.java's check win, I could extract my
      leader board code/GUI into a separate file and handle reading, writing, and paining the GUI there. 
      
      I think I did a good job of encapsulating private state, I made sure to use lots of getter functions
      to retrieve data between classes.
    
    
    
    ========================
    =: External Resources :=
    ========================
    
    - Cite any external resources (libraries, images, tutorials, etc.) that you may
      have used while implementing your game.
      1. https://docs.oracle.com/javase/tutorial/uiswing/components/panel.html and the other tutorials linked
      on this page to figure out the basics of swing.
      
      2.https://web.mit.edu/6.005/www/sp14/psets/ps4/java-6-tutorial/components.html to visually identify what
      I wanted.