Pebble-Game

Multithreaded game & test suite, created using Java and JUnit 4 in 2019.

Requirements

In this assignment you are to model a game involving multiple competing players, in a thread-safe fashion. The game being modelled has a strictly positive number of players. There are six bags of pebbles in the game, three white bags (A, B and C) and three black bags (X, Y and Z). At the start of the game the white bags are empty and the black bags are full. Each player takes 10 pebbles from a black bag (the black bag each player selects is chosen at random). Each pebble has an integer weight value.

If the weight of pebbles held by a player is 100, then they have won. They should immediately announce this fact to other players, and all other simulated players should stop playing (once they have ensured they only have 10 pebbles in their possession). If a player does not hold a winning hand they should discard a pebble to a white bag. They should then select one of the three black bags at random and draw a new pebble from this bag. This process should continue until either the player has won (has 10 pebbles with a total combined weight of 100), or until another player has won and the game has ended.

On starting, the command-line program should request the number of players, and after this has been entered it should then request the location of three files in turn containing the weight of each of the pebbles used in the black bags at the start of the game. An example of this is

The legal format of these files is as a comma-separated list of integers.

The program should perform exception-handling to cope with illegal player number entry and illegal file formatting/values and request the user to provide legal values until both inputs are legal, or until the user enters ‘E’ (in this case the program should exit).

The simulated game should have the following properties:

• Once a black bag is empty, all the pebbles from a white bag should be emptied into it. Bag X should be filled by bag A, bag Y filled by bag B, and bag Z filled by bag C.
• The process of drawing pebbles from a black bag should be uniformly at random – that is it should be equally probable to draw any of the pebbles in the bag.
• The players should act as concurrent threads, with the threading commencing before drawing their initial pebbles.
• Players should be implemented as nested classes within a PebbleGame application.
• Drawing and discarding should be an atomic action – additionally, the bag a pebble is discarded to, must be the paired white bag of the black bag that the last pebble draw was from. Specifically, if the last pebble was drawn from X, the next discard should be to A, if the last pebble drawn was from Y, the next discard should be to B, and if the last pebble drawn was from Z, the next discard should be to C.
• On loading the bag files, the program should ensure that each black bag contains at least 11 times as many pebbles as players. For example, if there are three players then there must be at least 33 pebbles.
• If a player attempts to draw from an empty black bag, the player should attempt to select another bag until they select a bag with pebbles.
• A player should never find an empty black bag if its paired white bag has pebbles within it.
• Pebbles must have a strictly positive weight – therefore the program should detect and warn the user if they are trying to use files where this is not the case.

After each draw and discard a player should write to a file the drawn/discarded value and the associated bag, and then the current values of the pebbles the player holds. I.e., if player 1 draws a pebble of weight 17 the following two lines should be written to

player1_output.txt: 
  player1 has drawn a 17 from bag Y 
  player1 hand is 1, 2, 45, 6, 7, 8, 56, 23, 12, 17

and if subsequently player 1 discards a pebble of weight 45 the following two lines should be written to

player1_output.txt:
  player1 has discarded a 45 to bag B
  player1 hand is 1, 2, 6, 7, 8, 56, 23, 12, 17

There are no restrictions on the standard Java libraries that you may use.

Simplified Requirements

Multiple players (multiple class?) (+ no. of players)

6 bags (ABC white; XYZ black)

t=0:

white bags empty; black bags full

Each player, select random black bag, 10 pebbles (integer weight, +)

t=terminate

Player’s pebbles’ weight = 100. -> announcement

Once player ensure hv 10 pebbles, stop.

Each player without weight 100, put 1 pebble into white.

Select black randomly, draw 1.

Repeat, til another player win.

t=0:

Command request no. of players

request locations of three files (weight of black pebbles)

Exception to handle illegal no. of players, file format & values: Ask till valid/ E.

If black bag == empty -> pebbles from white put there: X<-A; Y<-B; Z<-C

Prob. drawing a pebble, shared evenly

Player: concurrent thread: threading commencing before initial draw

Player, a nested class, within PebbleGame

Drawing & discarding atomic action. Discard pebble to white, by pairs above

In loading, ensure each black hv >= 11 x no. of players

If player draws from empty black, select another bag bag till that hv pebbles

Player cannot select an empty black if its pair white has pebbles

Draw & discard value & bag, into a file file for each player

player1_output.txt:						
     player1 has drawn a 17 from bag Y			
     player1 hand is 1, 2, 45, 6, 7, 8, 56, 23, 12, 17

player1_output.txt:
     player1 has discarded a 45 to bag B
     player1 hand is 1, 2, 6, 7, 8, 56, 23, 12, 17

No restrictions on standard Java lib.

Run

Make sure that the current directory is the pebblesTest directory. In order to run the testsuite,

• if on a Mac run the command: java -cp junit-4.12.jar:. TestRunner
• if on Windows run the command: java -cp junit-4.12.jar;. TestRunner

The expected output of the test is that all the tests will be passed