com.cedarsoft.lookup

Class LazyLookup<T>

java.lang.Object

com.cedarsoft.lookup.AbstractLookup

com.cedarsoft.lookup.LazyLookup<T>

All Implemented Interfaces:

Lookup

Direct Known Subclasses:

InstantiatorLookup

public abstract class LazyLookup<T>
extends AbstractLookup

Lazy implementation of lookup. This class will call getValue() as late as possible and cache the results.

Author:

Johannes Schneider (js@cedarsoft.com)

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	LazyLookup() Constructor for LazyLookup.

Method Summary

Modifier and Type	Method and Description
<T> void	addChangeListener(Class<T> type, LookupChangeListener<? super T> lookupChangeListener) Add a lookup change listener for a given type
void	addChangeListener(LookupChangeListener<?> lookupChangeListener) Adds a lookup change listener
<T> void	addChangeListenerWeak(Class<T> type, LookupChangeListener<? super T> lookupChangeListener) Add a lookup change listener that is wrapped within a WeakLookupChangeListener for a given type
void	addChangeListenerWeak(LookupChangeListener<?> lookupChangeListener) Adds a lookup change listener that is wrapped within a WeakLookupChangeListener
<T> void	bind(Class<T> type, LookupChangeListener<? super T> lookupChangeListener) Binds the given lookup change listener.
<T> void	bind(TypedLookupChangeListener<T> lookupChangeListener) Binds the given lookup change listener with the key retrieved from TypedLookupChangeListener#getType().
<T> void	bindWeak(Class<T> type, LookupChangeListener<? super T> lookupChangeListener) Binds the given lookup change listener that is wrapped within a WeakLookupChangeListener.
<T> void	bindWeak(TypedLookupChangeListener<T> lookupChangeListener) Binds the given lookup change listener (that is wrapped within a WeakLookupChangeListener) with the key retrieved from TypedLookupChangeListener#getType().
protected abstract T	createInstance() This method is only called once as soon as the first lookup request is made.
abstract Class<? extends T>	getType() The type the instance.
protected T	getValue() This method calls createInstance() and caches the value.
<T> T	lookup(Class<T> type) Lookup a given object
Map<Class<?>,Object>	lookups() Returns a map containing the available lookup objects.
<T> void	removeChangeListener(Class<T> type, LookupChangeListener<? super T> lookupChangeListener) Remove a lookup change listener from the given type
void	removeChangeListener(LookupChangeListener<?> lookupChangeListener) Remove a lookup change listener

Methods inherited from class com.cedarsoft.lookup.AbstractLookup

lookupNonNull

Methods inherited from class java.lang.Object

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

Constructor Detail

LazyLookup

protected LazyLookup()

Constructor for LazyLookup.

Method Detail

lookups

@Nonnull
public Map<Class<?>,Object> lookups()

Returns a map containing the available lookup objects. This method can throw an UnsupportedOperationException if the map is not available. If no exception is thrown the map must contain every possible lookup object.

Returns:

a map containing the available lookup objects.

createInstance

@Nonnull
protected abstract T createInstance()

This method is only called once as soon as the first lookup request is made.

Returns:

an instance of getType()

getType

public abstract Class<? extends T> getType()

The type the instance.

Returns:

a Class object.

lookup

@Nullable
public <T> T lookup(@Nonnull
                              Class<T> type)

Lookup a given object

This lookup calls getValue() when the parameter fits the type (getType()).

Type Parameters:

T - a T object.

Parameters:

type - the type

Returns:

the lookup object or null if nothing has been found

getValue

@Nullable
protected T getValue()

This method calls createInstance() and caches the value. Subclasses should not override this method but createInstance() instead.

Returns:

the value for the instance

bind

public <T> void bind(@Nonnull
                     Class<T> type,
                     @Nonnull
                     LookupChangeListener<? super T> lookupChangeListener)

Binds the given lookup change listener. Adds the given listener and calls LookupChangeListener#lookupChanged(LookupChangeEvent) for the first time.

Type Parameters:

T - a T object.

Parameters:

type - a Class object.

lookupChangeListener - the listener that is added

bind

public <T> void bind(@Nonnull
                     TypedLookupChangeListener<T> lookupChangeListener)

Binds the given lookup change listener with the key retrieved from TypedLookupChangeListener#getType(). Adds the given listener and calls LookupChangeListener#lookupChanged(LookupChangeEvent) for the first time.

Type Parameters:

T - a T object.

Parameters:

lookupChangeListener - the listener that is added

bindWeak

public <T> void bindWeak(@Nonnull
                         Class<T> type,
                         @Nonnull
                         LookupChangeListener<? super T> lookupChangeListener)

Binds the given lookup change listener that is wrapped within a WeakLookupChangeListener. Adds the given listener and calls LookupChangeListener#lookupChanged(LookupChangeEvent) for the first time.

Type Parameters:

T - a T object.

Parameters:

type - a Class object.

lookupChangeListener - the listener that is added

bindWeak

public <T> void bindWeak(@Nonnull
                         TypedLookupChangeListener<T> lookupChangeListener)

Binds the given lookup change listener (that is wrapped within a WeakLookupChangeListener) with the key retrieved from TypedLookupChangeListener#getType(). Adds the given listener and calls LookupChangeListener#lookupChanged(LookupChangeEvent) for the first time.

Type Parameters:

T - a T object.

Parameters:

lookupChangeListener - the listener that is added

addChangeListenerWeak

public void addChangeListenerWeak(@Nonnull
                                  LookupChangeListener<?> lookupChangeListener)

Adds a lookup change listener that is wrapped within a WeakLookupChangeListener

Parameters:

lookupChangeListener - the lookup change listener

addChangeListenerWeak

public <T> void addChangeListenerWeak(@Nonnull
                                      Class<T> type,
                                      @Nonnull
                                      LookupChangeListener<? super T> lookupChangeListener)

Add a lookup change listener that is wrapped within a WeakLookupChangeListener for a given type

Type Parameters:

T - a T object.

Parameters:

type - the type

lookupChangeListener - the listener

addChangeListener

public <T> void addChangeListener(@Nonnull
                                  Class<T> type,
                                  @Nonnull
                                  LookupChangeListener<? super T> lookupChangeListener)

Add a lookup change listener for a given type

Type Parameters:

T - a T object.

Parameters:

type - the type

lookupChangeListener - the listener

removeChangeListener

public <T> void removeChangeListener(@Nonnull
                                     Class<T> type,
                                     @Nonnull
                                     LookupChangeListener<? super T> lookupChangeListener)

Remove a lookup change listener from the given type

Type Parameters:

T - a T object.

Parameters:

type - the type of the listener

lookupChangeListener - the listener

removeChangeListener

public void removeChangeListener(@Nonnull
                                 LookupChangeListener<?> lookupChangeListener)

Remove a lookup change listener

Parameters:

lookupChangeListener - the listener that is removed from *all* types

addChangeListener

public void addChangeListener(@Nonnull
                              LookupChangeListener<?> lookupChangeListener)

Adds a lookup change listener

Parameters:

lookupChangeListener - the lookup change listener