26.8. Number Guess Example: Console Output

You have 5 out of 5 guesses left.
Please enter your guess from 0 to 100
50
Your guess was too high
You have 4 out of 5 guesses left.
Please enter your guess from 0 to 100
25
Your guess was too low
You have 3 out of 5 guesses left.
Please enter your guess from 0 to 100
37
Your guess was too low
You have 2 out of 5 guesses left.
Please enter your guess from 0 to 100
44
Your guess was too low
You have 1 out of 5 guesses left.
Please enter your guess from 0 to 100
47
Your guess was too low
You have no more guesses
The correct guess was 48
  • Since the file NumberGuess.java contains a main() method, it can be run as a standard Java application, either from the command line or via the IDE. A typical game might result in the interaction above. The numbers in bold were typed in by the user.
  • The main() method of NumberGuessExample.java loads a Rule Base, creates a Stateful Session and inserts Game, GameRules and RandomNumber (containing the target number) objects into it. The method also sets the process flow to be used and fires all rules. Control passes to the RuleFlow.
  • The RuleFlow file NumberGuess.rf begins at the "Start" node.
  • At the Guess node, the appropriate Rule Flow Group ("Get user Guess") is enabled. In this case the Rule "Guess" (in the NumberGuess.drl file) is triggered. This rule displays a message to the user, takes the response, and puts it into Working Memory. Flow passes to the next Rule Flow Node.
  • At the next node, "Guess Correct", constraints inspect the current session and decide which path to take.
    If the guess in step 4 was too high or too low, flow proceeds along a path which has an action node with normal Java code printing a suitable message and a Rule Flow Group causing a highest guess or lowest guess rule to be triggered. Flow passes from these nodes to step 6.
    If the guess in step 4 was right, we proceed along the path towards the end of the RuleFlow. Before this, an action node with normal Java code prints a statement "you guessed correctly". There is a join node here (just before the Rule Flow end) so the no-more-guesses path (step 7) can also terminate the RuleFlow.
  • Control passes as per the RuleFlow via a join node to a "guess incorrect" RuleFlow Group (triggering a rule to retract a guess from Working Memory) and onto the "More guesses" decision node.
  • The "More guesses" decision node (on the right hand side of the rule flow) uses constraints, again looking at values that the rules have put into the working memory, to decide if the user has more guesses and. If so, it moves to step 3. If not, the user proceeds to the end of the RuleFlow via a RuleFlow Group that triggers a rule stating "you have no more guesses".
  • The loop over steps 3 to 7 continues until the number is guessed correctly or the user runs out of guesses.
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