org.gcube.common.core.utils.handlers.lifetime
Class State

java.lang.Object
  org.gcube.common.core.utils.handlers.lifetime.State

Direct Known Subclasses:

State.Created, State.Done, State.Failed, State.Running, State.Suspended

public abstract class State
extends Object

Partial implementation for models of distinguished states in the lifetime of a GCUBEIHandler.

A subclass that models a given state:

• must define a constructor that delegates to the constructor of State with a list of other states from which a handler may transition to the state;
• must implement toString() to facilitate the management of the state;
• must implement getLifetimeEvent() to produce a Event.LifetimeEvent associated with a handler's transition to the state.
  States that are meant to be private can simply return null.
• may override onEnter() and onExit() to specify behaviour to be executed immediately after a handler moves into the state and immediately before a handler leaves the state;

Author:

Fabio Simeoni (University of Strathclyde)

Nested Class Summary

static class	State.Created Specialises State for the (private) start state of a handler.
static class	State.Done Specialises State for the state of a handler that has completed execution.
static class	State.Failed Specialises State for the state of a handler that has failed prior or during its execution.
static class	State.Running Specialises State for the state of a handler that is executing.
static class	State.Suspended Specialises State for the state of a handler that has suspended its execution.

Constructor Summary

protected

State() Creates a new instance.

Method Summary

protected abstract void	addPrevious(List<State> previous) Adds the states from which a handler may transition to this state.
boolean	equals(Object o)
Event.LifetimeEvent	getLifetimeEvent() Returns a Event.LifetimeEvent for the transition to this state.
List<State>	getPrevious() Returns the states from which a handler may transition to this state.
int	hashCode()
void	onEnter() Invoked by upon transitioning to this state.
void	onExit() Invoked upon transitioning from this state.
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

State

protected State()

Creates a new instance.

Method Detail

addPrevious

protected abstract void addPrevious(List<State> previous)

Adds the states from which a handler may transition to this state.

Parameters:

previous - the previous states.

getPrevious

public final List<State> getPrevious()

Returns the states from which a handler may transition to this state.

Returns:

the states.

toString

public String toString()

Overrides:

toString in class Object

onEnter

public void onEnter()
             throws Exception

Invoked by upon transitioning to this state.

Throws:

Exception - if the transition could not occur.

onExit

public void onExit()
            throws Exception

Invoked upon transitioning from this state.

Throws:

Exception - if the transition could not occur.

getLifetimeEvent

public Event.LifetimeEvent getLifetimeEvent()

Returns a Event.LifetimeEvent for the transition to this state.

Return null if the transition should not be notified.

Returns:

the event.

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object