org.apache.flink.streaming.examples.statemachine.dfa

Enum State

java.lang.Object

java.lang.Enum<State>

org.apache.flink.streaming.examples.statemachine.dfa.State

All Implemented Interfaces:

Serializable, Comparable<State>

public enum State
extends Enum<State>

The State captures the main functionality of the state machine. It represents a specific state in the state machine, and holds all transitions possible from a specific state.

The state transition diagram is as follows:

           +--[a]--> W --[b]--> Y --[e]---+
           |                    ^         |
   Initial-+                    |         |
           |                    |         +--> (Z)-----[g]---> Terminal
           +--[c]--> X --[b]----+         |
                     |                    |
                     +--------[d]---------+
 

Enum Constant Summary

Enum Constants

Enum Constant and Description
Initial The initial state from which all state sequences start.
InvalidTransition Special state returned by the State.transition(...) function when attempting an illegal state transition.
Terminal The terminal state in the state machine.
W State 'W'.
X State 'X'.
Y State 'Y'.
Z State 'Z'.

Method Summary

Modifier and Type	Method and Description
boolean	isTerminal() Checks if this state is a terminal state.
EventType	randomInvalidTransition(Random rnd) Returns an event type that, if applied as a transition on this state, will result in an illegal state transition.
EventTypeAndState	randomTransition(Random rnd) Picks a random transition, based on the probabilities of the outgoing transitions of this state.
State	transition(EventType evt) Gets the state after transitioning from this state based on the given event.
static State	valueOf(String name) Returns the enum constant of this type with the specified name.
static State[]	values() Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Detail

Terminal

public static final State Terminal

The terminal state in the state machine.

InvalidTransition

public static final State InvalidTransition

Special state returned by the State.transition(...) function when attempting an illegal state transition.

Z

public static final State Z

State 'Z'.

Y

public static final State Y

State 'Y'.

X

public static final State X

State 'X'.

W

public static final State W

State 'W'.

Initial

public static final State Initial

The initial state from which all state sequences start.

Method Detail

values

public static State[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (State c : State.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static State valueOf(String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

IllegalArgumentException - if this enum type has no constant with the specified name

NullPointerException - if the argument is null

isTerminal

public boolean isTerminal()

Checks if this state is a terminal state. A terminal state has no outgoing transitions.

transition

public State transition(EventType evt)

Gets the state after transitioning from this state based on the given event. If the transition is valid, this returns the new state, and if this transition is illegal, it returns [[InvalidTransition]].

Parameters:

evt - The event that defined the transition.

Returns:

The new state, or [[InvalidTransition]].

randomTransition

public EventTypeAndState randomTransition(Random rnd)

Picks a random transition, based on the probabilities of the outgoing transitions of this state.

Parameters:

rnd - The random number generator to use.

Returns:

A pair of (transition event , new state).

randomInvalidTransition

public EventType randomInvalidTransition(Random rnd)

Returns an event type that, if applied as a transition on this state, will result in an illegal state transition.

Parameters:

rnd - The random number generator to use.

Returns:

And event type for an illegal state transition.