{"id":7915,"date":"2024-11-14T16:00:31","date_gmt":"2024-11-14T16:00:31","guid":{"rendered":"https:\/\/msgprogramator.sk\/?p=7915"},"modified":"2026-04-01T11:58:09","modified_gmt":"2026-04-01T11:58:09","slug":"rock-paper-scissors","status":"publish","type":"post","link":"https:\/\/msgprogramator.sk\/en\/rock-paper-scissors\/","title":{"rendered":"How to program an artificial intelligence (AI) game in Java – rock, paper, scissors"},"content":{"rendered":"

Who doesn\u2019t know the popular game Rock, Paper, Scissors we used to play as kids? But who would have thought back then that one day they would be able to program it in their favourite programming language, for example Java<\/a>.<\/p>\n

Few people know that Rock, Paper, Scissors<\/a> is a hand game that is said to have originated in China, from where it spread to Japan. There it originated in its modern form as we know it, and in the early 20th century it spread very quickly around the world.<\/p>\n

Rock, paper, scissors rules<\/h2>\n

We certainly don’t need to imagine the rules of the game. But if there is anyone who doesn’t know it yet, we will briefly mention them.<\/p>\n

It is most often played by two players (or more), each of whom subconsciously chooses either a rock, paper or scissors. On the count of one, two, three, both players simultaneously show what they have chosen – rock (closed fist), or scissors (using index and middle fingers), or paper (open hand). The result of the game, which is of course played over multiple rounds, is a draw, a win, or a loss.<\/p>\n

The player who plays the stone beats the other player who chooses the scissors (the stone dulls the scissors), but loses to the player who played the paper (the paper covers the rock). The player with paper loses to the player who chose scissors (scissors cut the paper). If both players choose the same shape, the game is a tie and is usually repeated to break the tie.<\/p>\n

Rock, paper, scissors is often used as a method of fair selection among children when it comes to which child will start something first.<\/p>\n

Did you know that?
\nVarious competitive tournaments were also organized for Stone, Paper, Scissors. For example, the winners of the tournaments took home between $5,000 and $20,000.<\/p>\n

Rock, paper, scissors in Java<\/h2>\n

Today we will program this game together in Java. To make this game more interesting for players to play, we will also program an artificial intelligence (AI)<\/strong> that will not randomly decide whether to use a rock, paper, or scissors in each round, but will choose one of the default strategies in each round. Of course the player will have no idea what gesture the computer AI has just chosen.<\/p>\n

Interesting fact<\/h3>\n

You definitely don’t want to play Rock, Paper, Scissors with a robot. In 2012, researchers at the Ishikawa Watanabe Laboratory at the University of Tokyo created a robotic arm that can win any game against a human opponent. Using a high-speed camera, the robot recognizes within one millisecond what shape the human hand is making and then creates the corresponding winning shape.<\/p>\n

Game concept with AI<\/h2>\n

The game will be played for a predefined number of rounds, which will be specified when the game instance is created. Since the game rounds are very fast and we want to test the behavior of the AI, we set the default value for the number of rounds to 20.<\/p>\n

At the start of each round we will need to record the player’s selection, select the AI strategy for that round and use that to determine the AI computer’s selection. The AI will choose randomly from the default strategies, making it difficult for the player to determine what gesture the computer will play.<\/p>\n

We then check who picked what and allocate points accordingly, +1 for a win, 0 for a draw or a loss. The first one to reach 20 points wins the game.<\/p>\n

Game strategies for AI<\/h2>\n

The game’s artificial intelligence will record the player’s winning gestures and decide which gesture to play based on the history. Basic strategies will include:<\/p>\n