25.5. Sudoku Example: Classes and Objects

An object belonging to the Setting class is used for triggering the operations that accompany the allocation of a value. The presence of a Setting fact is used in all rules that should detect changes in the process. This is to avoid reactions to inconsistent intermediary states.

An object of class Stepping is used in a low priority rule to execute an emergency halt when a "Step" ends unexpectedly. This indicates that the puzzle cannot be solved by the program.

The class org.drools.examples.sudoku.SudokuExample implements a Java application combining the above components.