org.moeaframework.algorithm
Class AbstractAlgorithm

java.lang.Object
  org.moeaframework.algorithm.AbstractAlgorithm

All Implemented Interfaces:

Algorithm

Direct Known Subclasses:

AbstractEvolutionaryAlgorithm, AbstractPSOAlgorithm, CMAES, MOEAD, PISAAlgorithm, RandomSearch

public abstract class AbstractAlgorithm
extends Object
implements Algorithm

Abstract class providing default implementations for several Algorithm methods. All method extending this class must use the evaluate(org.moeaframework.core.Solution) method to evaluate a solution. This is mandatory to ensure the getNumberOfEvaluations() method returns the correct result.

Subclasses should avoid overriding the step() method and instead override the initialize() and iterate() methods individually.

Field Summary

protected boolean	initialized true if the initialize() method has been invoked; false otherwise.
protected int	numberOfEvaluations The number of times the evaluate(org.moeaframework.core.Solution) method was invoked.
protected Problem	problem The problem being solved.
protected boolean	terminated true if the terminate() method has been invoked; false otherwise.

Constructor Summary

AbstractAlgorithm(Problem problem)
Constructs an abstract algorithm for solving the specified problem.

Method Summary

void	evaluate(Solution solution) Evaluates the specified solution for the problem being solved by this algorithm.
void	evaluateAll(Iterable<Solution> solutions) Evaluates the specified solutions.
void	evaluateAll(Solution[] solutions) Evaluates the specified solutions.
protected void	finalize() Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
int	getNumberOfEvaluations() Returns the number of times the evaluate method was invoked.
Problem	getProblem() Returns the problem being solved by this algorithm.
Serializable	getState() Returns a Serializable object representing the internal state of this algorithm.
protected void	initialize() Performs any initialization that is required by this algorithm.
boolean	isInitialized() Returns true if the initialize() method has been invoked; false otherwise.
boolean	isTerminated() Returns true if this algorithm is terminated; false otherwise.
protected abstract void	iterate() Performs one iteration of the algorithm.
void	setState(Object state) Sets the internal state of of this algorithm.
void	step() This method first checks if the algorithm is initialized.
void	terminate() Implementations should always invoke super.terminate() to ensure the hierarchy is terminated correctly.

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.moeaframework.core.Algorithm

getResult

Field Detail

problem

protected final Problem problem

The problem being solved.

numberOfEvaluations

protected int numberOfEvaluations

The number of times the evaluate(org.moeaframework.core.Solution) method was invoked.

initialized

protected boolean initialized

true if the initialize() method has been invoked; false otherwise.

terminated

protected boolean terminated

true if the terminate() method has been invoked; false otherwise.

Constructor Detail

AbstractAlgorithm

public AbstractAlgorithm(Problem problem)

Constructs an abstract algorithm for solving the specified problem.

Parameters:

problem - the problem being solved

Method Detail

evaluateAll

public void evaluateAll(Iterable<Solution> solutions)

Evaluates the specified solutions. This method calls evaluate(Solution) on each of the solutions. Subclasses should prefer calling this method over evaluate whenever possible, as this ensures the solutions can be evaluated in parallel.

Parameters:

solutions - the solutions to evaluate

evaluateAll

public void evaluateAll(Solution[] solutions)

Evaluates the specified solutions. This method is equivalent to evaluateAll(Arrays.asList(solutions)).

Parameters:

solutions - the solutions to evaluate

evaluate

public void evaluate(Solution solution)

Description copied from interface: Algorithm

Evaluates the specified solution for the problem being solved by this algorithm.

Specified by:

evaluate in interface Algorithm

Parameters:

solution - the solution to be evaluated

See Also:

Problem.evaluate(Solution)

getNumberOfEvaluations

public int getNumberOfEvaluations()

Description copied from interface: Algorithm

Returns the number of times the evaluate method was invoked. This is the primary measure of runtime for optimization algorithms.

Specified by:

getNumberOfEvaluations in interface Algorithm

Returns:

the number of times the evaluate method was invoked

getProblem

public Problem getProblem()

Description copied from interface: Algorithm

Returns the problem being solved by this algorithm.

Specified by:

getProblem in interface Algorithm

Returns:

the problem being solved by this algorithm

initialize

protected void initialize()

Performs any initialization that is required by this algorithm. This method is called automatically by the first invocation of step(), but may also be called manually prior to any invocations of step. Implementations should always invoke super.initialize() to ensure the hierarchy is initialized correctly.

Throws:

AlgorithmInitializationException - if the algorithm has already been initialized

isInitialized

public boolean isInitialized()

Returns true if the initialize() method has been invoked; false otherwise.

Returns:

true if the initialize() method has been invoked; false otherwise

step

public void step()

This method first checks if the algorithm is initialized. If not, the initialize() method is invoked. If initialized, all calls to step invoke iterate(). Implementations should override the initialize and iterate methods in preference to modifying this method.

Specified by:

step in interface Algorithm

Throws:

AlgorithmTerminationException - if the algorithm has already terminated

iterate

protected abstract void iterate()

Performs one iteration of the algorithm. This method should be overridden by implementations to perform each logical iteration of the algorithm.

isTerminated

public boolean isTerminated()

Description copied from interface: Algorithm

Returns true if this algorithm is terminated; false otherwise.

Specified by:

isTerminated in interface Algorithm

Returns:

true if this algorithm is terminated; false otherwise

See Also:

Algorithm.terminate()

terminate

public void terminate()

Implementations should always invoke super.terminate() to ensure the hierarchy is terminated correctly. This method is automatically invoked during finalization, and need only be called directly if non-Java resources are in use.

Specified by:

terminate in interface Algorithm

Throws:

AlgorithmTerminationException - if the algorithm has already terminated

finalize

protected void finalize()
                 throws Throwable

Description copied from class: java.lang.Object

Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. A subclass overrides the finalize method to dispose of system resources or to perform other cleanup.

The general contract of finalize is that it is invoked if and when the Java^TM virtual machine has determined that there is no longer any means by which this object can be accessed by any thread that has not yet died, except as a result of an action taken by the finalization of some other object or class which is ready to be finalized. The finalize method may take any action, including making this object available again to other threads; the usual purpose of finalize, however, is to perform cleanup actions before the object is irrevocably discarded. For example, the finalize method for an object that represents an input/output connection might perform explicit I/O transactions to break the connection before the object is permanently discarded.

The finalize method of class Object performs no special action; it simply returns normally. Subclasses of Object may override this definition.

The Java programming language does not guarantee which thread will invoke the finalize method for any given object. It is guaranteed, however, that the thread that invokes finalize will not be holding any user-visible synchronization locks when finalize is invoked. If an uncaught exception is thrown by the finalize method, the exception is ignored and finalization of that object terminates.

After the finalize method has been invoked for an object, no further action is taken until the Java virtual machine has again determined that there is no longer any means by which this object can be accessed by any thread that has not yet died, including possible actions by other objects or classes which are ready to be finalized, at which point the object may be discarded.

The finalize method is never invoked more than once by a Java virtual machine for any given object.

Any exception thrown by the finalize method causes the finalization of this object to be halted, but is otherwise ignored.

Overrides:

finalize in class Object

Throws:

Throwable - the Exception raised by this method

getState

public Serializable getState()
                      throws NotSerializableException

Description copied from interface: Algorithm

Returns a Serializable object representing the internal state of this algorithm.

Specified by:

getState in interface Algorithm

Returns:

a Serializable object representing the internal state of this algorithm

Throws:

NotSerializableException - if this algorithm does not support serialization

setState

public void setState(Object state)
              throws NotSerializableException

Description copied from interface: Algorithm

Sets the internal state of of this algorithm.

Specified by:

setState in interface Algorithm

Parameters:

state - the internal state of this algorithm

Throws:

NotSerializableException - if this algorithm does not support serialization