io.github.lukehutch.fastclasspathscanner.utils

Class SingletonMap<K,V>

java.lang.Object

io.github.lukehutch.fastclasspathscanner.utils.SingletonMap<K,V>

public abstract class SingletonMap<K,V>
extends Object

A map from keys to singleton instances.

Constructor Summary

Constructors

Constructor and Description
SingletonMap()

Method Summary

Modifier and Type	Method and Description
void	clear() Clear the map.
boolean	createSingleton(K key) Initialize a value object for this key and return true, if this is the first time this key has been seen, otherwise return false.
V	get(K key) Get the singleton for a given key.
V	getOrCreateSingleton(K key) Check if the given key is in the map, and if so, return it.
abstract V	newInstance(K key) Construct a new singleton instance.
List<V>	values() Get all singletons in the map.

Methods inherited from class java.lang.Object

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

Constructor Detail

SingletonMap

public SingletonMap()

Method Detail

createSingleton

public boolean createSingleton(K key)
                        throws Exception

Initialize a value object for this key and return true, if this is the first time this key has been seen, otherwise return false.

Throws:

Exception - if newInstance(key) throws an exception.

IllegalArgumentException - if newInstance(key) returns null.

getOrCreateSingleton

public V getOrCreateSingleton(K key)
                       throws Exception

Check if the given key is in the map, and if so, return it. If not, create a singleton value for that key, and return the created value.

Throws:

Exception - if newInstance(key) throws an exception.

IllegalArgumentException - if newInstance(key) returns null.

newInstance

public abstract V newInstance(K key)
                       throws Exception

Construct a new singleton instance.

Throws:

Exception

get

public V get(K key)
      throws InterruptedException

Get the singleton for a given key.

Returns:

the new singleton instance, initialized by calling newInstance, or null if createSingleton() or getOrCreateSingleton() has not yet been called. Also returns null if newInstance() threw an exception or returned null while calling either of these methods.

Throws:

InterruptedException

values

public List<V> values()
               throws InterruptedException

Get all singletons in the map.

Throws:

InterruptedException

clear

public void clear()

Clear the map.