Exercise

Life of the Ants Wiki | Exercise

Story

In an ant colony there are four different castes: workers, soldiers, drones, and there is one queen. The colony area is square (has a width), and the ants live and move within the borders of the colony.

Each ant changes position in every timestep, according to a caste-specific rule:

• the queen sits in the middle and does not move
• the workers normally make one step in one of the four directions, chosen randomly before each move
• the soldiers "patrol" close to their starting position; this means that in a 4-cycle they step one and turn to the left (towards North, East, South, and West, and then they start the cycle again)
• the drones always try to make one step towards the Queen. When they get next to the queen, they have a chance that she is in the mood of mating. In this happy case they say "HALLELUJAH", and stay there for 10 timesteps. After that they are kicked off to a random position at the edge of the colony. If the queen isn't in the mood, drones say ":(", and are kicked away instantly.

The queen’s mating mood is following this rule: after a successful mating she sets a countdown timer (starting from some time between 50 and 100 timesteps) to get in the mood again.

What are you going to learn?

• design an application using a class diagram
• think in OOP way
• do a little of algorithms

Tasks

1. Plan and draw the class diagram for this simulation on draw.io. Create and upload a plan. After finishing the implementation, update the plan to show the end result, and uplad it as well.

   • The class diagram plan is added with the first commit as diagram-plan.png to the repository, displaying all the classes and methods mentioned in the story
   • The final class diagram is uploaded as diagram-final.png. It must mirror the implemented simulation exactly.

2. A colony is created with a width value setting its range, a width by width square. A colony is created with a width value setting its range, a width by width square. A queen is created at construction time positioned at the center of the colony. Colony also has a generateAnts method with three integer arguments that set the number of drones, workers, and soldiers to be created, respectively. It also has an update method which invokes each ants' onUpdate method, and a display method which displays the colony "map" on the console.

   • Upon construction, the value of width is set, and a queen is created at the center
   • Method update that calls move on each ants
   • Method display prints all ants in the colony as a width by width map, placing the initials of the ants (Q, W, S, D) at their actual positions. If more then one ants share the same position, display the letter for one of them

3. Implement the main loop of the simulation: step forward one time unit and display the state of the colony every time when the Enter key is pressed. Hitting q and Enter exits the program.

   • The simulation creates a colony and populates it with all kinds of ants
   • The simulation updates once and displays the state of the colony after hitting Enter
   • The program stops one after hitting q and Enter

4. Implement the basic movement behavior of ants. Ensure that if the step would cause an ant to leave the range of the colony, it won't move.

   • Workers move one step into a random direction
   • Soldiers patrol by stepping one and turning to the left in every time step
   • Drones move one step closer to the queen. If they reach the queen's position, they get instantly kicked away to a random position, exactly width / 2 steps away
   • The queen does not move at all
   • Ants stay within the range of the colony

5. Implement the mating behavior of drones and the queen.

   • The queen's mating mood is set by a counter which is decremented by one in each step. If it reaches zero, the next drone encounter will end up in mating. This resets the counter to a random value between 50 and 100
   • The successful drone stays next to the queen for 10 steps after mating, before getting kicked away as usual

General requirements

None

Hints

• Keep in mind all 4 basic principles of OOP, and also clean code! The names should be meaningful and descriptive. When doing right, most methods in the code look like simple but readable English sentences.
• Lot of implementation details are not ant-specific but belong to general 2D geometry: meaning of coordinates, stepping into directions and changing the coordinates, turning to left or right. Try to abstract out and encapsulate these aspects to the to classes in the geometry subpackage, Position and Direction.
• Direction is an enumerated class with four instances (NORTH, EAST, SOUTH, and WEST). Enum classes can be extended with fields and methods as well. Use this feature to encapsulate everything that belongs to them!
• When displaying shapes on the console, a square looks like a 1:2 rectangle, following the shape of the character unit. You can hack the view (and strictly only the view!) by adding one space after each displayed character, effectively stretching the view horizontally by a factor of 2.

Background materials

• Java enums