Package org.optaplanner.core.api.solver

Interface Solver<Solution_>

Type Parameters:

Solution_ - the solution type, the class with the PlanningSolution annotation

All Known Implementing Classes:

AbstractSolver, DefaultSolver, PartitionSolver

public interface Solver<Solution_>

A Solver solves a planning problem and returns the best solution found. It's recommended to create a new Solver instance for each dataset.

To create a Solver, use SolverFactory.buildSolver(). To solve a planning problem, call solve(Object). To solve a planning problem without blocking the current thread, use SolverManager instead.

These methods are not thread-safe and should be called from the same thread, except for the methods that are explicitly marked as thread-safe. Note that despite that solve(Solution_) is not thread-safe for clients of this class, that method is free to do multithreading inside itself.

Method Summary

Modifier and Type	Method	Description
void	addEventListener(SolverEventListener<Solution_> eventListener)
void	addProblemChange(ProblemChange<Solution_> problemChange)	Schedules a ProblemChange to be processed.
void	addProblemChanges(List<ProblemChange<Solution_>> problemChangeList)	Schedules multiple ProblemChanges to be processed.
boolean	addProblemFactChange(ProblemFactChange<Solution_> problemFactChange)	Deprecated, for removal: This API element is subject to removal in a future version. Prefer addProblemChange(ProblemChange).
boolean	addProblemFactChanges(List<ProblemFactChange<Solution_>> problemFactChangeList)	Deprecated, for removal: This API element is subject to removal in a future version. Prefer addProblemChanges(List).
boolean	isEveryProblemChangeProcessed()	Checks if all scheduled ProblemChanges have been processed.
boolean	isEveryProblemFactChangeProcessed()	Deprecated, for removal: This API element is subject to removal in a future version. Prefer isEveryProblemChangeProcessed().
boolean	isSolving()	This method is thread-safe.
boolean	isTerminateEarly()	This method is thread-safe.
void	removeEventListener(SolverEventListener<Solution_> eventListener)
Solution_	solve(Solution_ problem)	Solves the planning problem and returns the best solution encountered (which might or might not be optimal, feasible or even initialized).
boolean	terminateEarly()	Notifies the solver that it should stop at its earliest convenience.

Method Details

solve

Solution_ solve(Solution_ problem)

Solves the planning problem and returns the best solution encountered (which might or might not be optimal, feasible or even initialized).

It can take seconds, minutes, even hours or days before this method returns, depending on the termination configuration. To terminate a Solver early, call terminateEarly().

Parameters:

problem - never null, a PlanningSolution, usually its planning variables are uninitialized

Returns:

never null, but it can return the original, uninitialized PlanningSolution with a null Score.

See Also:

• terminateEarly()

terminateEarly

boolean terminateEarly()

Notifies the solver that it should stop at its earliest convenience. This method returns immediately, but it takes an undetermined time for the solve(Solution_) to actually return.

If the solver is running in daemon mode, this is the only way to terminate it normally.

This method is thread-safe. It can only be called from a different thread because the original thread is still calling solve(Object).

Returns:

true if successful, false if was already terminating or terminated

See Also:

• isTerminateEarly()
• Future.cancel(boolean)

isSolving

boolean isSolving()

This method is thread-safe.

Returns:

true if the solve(Solution_) method is still running.

isTerminateEarly

boolean isTerminateEarly()

This method is thread-safe.

Returns:

true if terminateEarly has been called since the Solver started.

See Also:

• Future.isCancelled()

addProblemChange

void addProblemChange(ProblemChange<Solution_> problemChange)

Schedules a ProblemChange to be processed.

As a side effect, this restarts the Solver, effectively resetting all Terminations, but not terminateEarly().

This method is thread-safe. Follows specifications of BlockingQueue.add(Object) with by default a capacity of Integer.MAX_VALUE.

To learn more about problem change semantics, please refer to the ProblemChange Javadoc.

Parameters:

problemChange - never null

See Also:

• addProblemChanges(List)

addProblemChanges

void addProblemChanges(List<ProblemChange<Solution_>> problemChangeList)

Schedules multiple ProblemChanges to be processed.

As a side effect, this restarts the Solver, effectively resetting all Terminations, but not terminateEarly().

This method is thread-safe. Follows specifications of BlockingQueue.add(Object) with by default a capacity of Integer.MAX_VALUE.

To learn more about problem change semantics, please refer to the ProblemChange Javadoc.

Parameters:

problemChangeList - never null

See Also:

• addProblemChange(ProblemChange)

isEveryProblemChangeProcessed

boolean isEveryProblemChangeProcessed()

Checks if all scheduled ProblemChanges have been processed.

This method is thread-safe.

Returns:

true if there are no ProblemChanges left to do

addProblemFactChange

@Deprecated(forRemoval=true)
boolean addProblemFactChange(ProblemFactChange<Solution_> problemFactChange)

Deprecated, for removal: This API element is subject to removal in a future version.

Prefer addProblemChange(ProblemChange).

This method is deprecated. Schedules a ProblemFactChange to be processed.

As a side-effect, this restarts the Solver, effectively resetting all terminations, but not terminateEarly().

This method is thread-safe. Follows specifications of BlockingQueue.add(Object) with by default a capacity of Integer.MAX_VALUE.

Parameters:

problemFactChange - never null

Returns:

true (as specified by Collection.add(E))

See Also:

• addProblemFactChanges(List)

addProblemFactChanges

@Deprecated(forRemoval=true)
boolean addProblemFactChanges(List<ProblemFactChange<Solution_>> problemFactChangeList)

Deprecated, for removal: This API element is subject to removal in a future version.

Prefer addProblemChanges(List).

This method is deprecated. Schedules multiple ProblemFactChanges to be processed.

As a side-effect, this restarts the Solver, effectively resetting all terminations, but not terminateEarly().

This method is thread-safe. Follows specifications of Collection.addAll(Collection) with by default a capacity of Integer.MAX_VALUE.

Parameters:

problemFactChangeList - never null

Returns:

true (as specified by Collection.add(E))

See Also:

• addProblemFactChange(ProblemFactChange)

isEveryProblemFactChangeProcessed

@Deprecated(forRemoval=true)
boolean isEveryProblemFactChangeProcessed()

Deprecated, for removal: This API element is subject to removal in a future version.

Prefer isEveryProblemChangeProcessed().

This method is deprecated. Checks if all scheduled ProblemFactChanges have been processed.

This method is thread-safe.

Returns:

true if there are no ProblemFactChanges left to do

addEventListener

void addEventListener(SolverEventListener<Solution_> eventListener)

Parameters:

eventListener - never null

removeEventListener

void removeEventListener(SolverEventListener<Solution_> eventListener)

Parameters:

eventListener - never null