Prisoner's Dilemma

Prisoner's dilemma game, to practice with Java and Scala. The purpose of the game is to be in jail as few as possible, depending on your answer to the Police and the other prisoner answer. More information about the prisoner's dilemma itself can be found in wikipedia.

Implementing a Prisoner

The user must only implement one class, that subclasses Prisoner, and implements their abstract methods giveAnswer and notifyPoliceResponse. Java or Scala can be used.

The giveAnswer method will tell the Police the answer of the prisoner in every iteration (could and should be different during the game).

When the Police have the answers from both prisoners, they will inform the sentence to each one. These sentences could be:

• FREE. This prisioner talked, but the other didn't. He goes free.
• MINOR. Both didn't talk, so both have minor sentence (1 year in jail).
• MEDIUM. Both talked, so the sentence is medium for both (5 years).
• MAJOR. This prisoner didn't talk, but the other betrayed him. Maximum sentence of 10 years.

Examples

There are two sample implemented prisoners, GentlePrisoner (that will never talk), and EvilPrisoner (that will always try to betray the other). Both samples will always give the same response, as can be seen in giveAnswer overriden method.

Execution and results

First both prisoners must be run (if they are in the same machine, they should use different ports). Both will show:

Waiting for Police...

When the Police is run, the contest will start, and at the end, some statistics will be shown. To override default values (localhost prisoners on ports 5000 and 5001, and 50 rounds), the arguments can be passed to Police process:

java es.greuze.sandbox.prisoners.Police localhost 5000 localhost 5001 10

This is an example results with 10 rounds within GentlePrisoner and EvilPrisoner:

From a total of 10 round:

Prisoner 1 results:
0 times free (0.0%)
0 times minor (0.0%)
0 times medium (0.0%)
10 times major (100.0%)
With an average of 10.0 years of jail

Prisoner 2 results:
10 times free (100%)
0 times minor (0%)
0 times medium (0%)
0 times major (0%)
With an average of 0.0 years of jail