com.googlecode.objectify

Class Key<T>

java.lang.Object

com.googlecode.objectify.Key<T>

All Implemented Interfaces:

Serializable, Comparable<Key<?>>

public class Key<T>
extends Object
implements Serializable, Comparable<Key<?>>

A typesafe wrapper for the datastore Key object.

Author:

Jeff Schnitzer , Scott Hernandez

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected Key<?>	parent Cache the instance of the parent wrapper to avoid unnecessary garbage
protected com.google.appengine.api.datastore.Key	raw

Method Summary

Methods

Modifier and Type	Method and Description
int	compareTo(Key<?> other) Compares based on comparison of the raw key
static <T> Key<T>	create(Class<? extends T> kindClass, long id) Key.create(Blah.class, id) is easier to type than new Key(Blah.class, id)
static <T> Key<T>	create(Class<? extends T> kindClass, String name) Key.create(Blah.class, name) is easier to type than new Key(Blah.class, name)
static <T> Key<T>	create(com.google.appengine.api.datastore.Key raw) Key.create(key) is easier to type than new Key(key)
static <T> Key<T>	create(Key<?> parent, Class<? extends T> kindClass, long id) Key.create(parent, Blah.class, id) is easier to type than new Key(parent, Blah.class, id)
static <T> Key<T>	create(Key<?> parent, Class<? extends T> kindClass, String name) Key.create(parent, Blah.class, name) is easier to type than new Key(parent, Blah.class, name)
static <T> Key<T>	create(String webSafeString) Key.create(webSafeString) is easier to type than new Key(webSafeString)
static <T> Key<T>	create(T pojo) Create a key from a registered POJO entity.
boolean	equals(Object obj)
boolean	equivalent(Key<T> other) A type-safe equivalence comparison
boolean	equivalent(Ref<T> other) A type-safe equivalence comparison
long	getId()
String	getKind()
static String	getKind(Class<?> clazz) Determines the kind for a Class, as understood by the datastore.
String	getName()
<V> Key<V>	getParent()
com.google.appengine.api.datastore.Key	getRaw()
<V> Key<V>	getRoot() Gets the root of a parent graph of keys.
String	getString() Call KeyFactory.keyToString() on the underlying Key.
int	hashCode()
static <V> Key<V>	key(com.google.appengine.api.datastore.Key raw) Easy null-safe conversion of the raw key.
static com.google.appengine.api.datastore.Key	key(Key<?> typed) Easy null-safe conversion of the typed key.
String	toString() Creates a human-readable version of this key
static <T> Key<T>	valueOf(String webSafeString) This is an alias for Key.create(String) which exists for JAX-RS compliance.

Methods inherited from class java.lang.Object

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

Field Detail

raw

protected com.google.appengine.api.datastore.Key raw

parent

protected transient Key<?> parent

Cache the instance of the parent wrapper to avoid unnecessary garbage

Method Detail

create

public static <T> Key<T> create(com.google.appengine.api.datastore.Key raw)

Key.create(key) is easier to type than new Key(key)

create

public static <T> Key<T> create(Class<? extends T> kindClass,
                long id)

Key.create(Blah.class, id) is easier to type than new Key(Blah.class, id)

create

public static <T> Key<T> create(Class<? extends T> kindClass,
                String name)

Key.create(Blah.class, name) is easier to type than new Key(Blah.class, name)

create

public static <T> Key<T> create(Key<?> parent,
                Class<? extends T> kindClass,
                long id)

Key.create(parent, Blah.class, id) is easier to type than new Key(parent, Blah.class, id)

create

public static <T> Key<T> create(Key<?> parent,
                Class<? extends T> kindClass,
                String name)

Key.create(parent, Blah.class, name) is easier to type than new Key(parent, Blah.class, name)

create

public static <T> Key<T> create(String webSafeString)

Key.create(webSafeString) is easier to type than new Key(webSafeString)

valueOf

public static <T> Key<T> valueOf(String webSafeString)

This is an alias for Key.create(String) which exists for JAX-RS compliance.

create

public static <T> Key<T> create(T pojo)

Create a key from a registered POJO entity.

getRaw

public com.google.appengine.api.datastore.Key getRaw()

Returns:

the raw datastore version of this key

getId

public long getId()

Returns:

the id associated with this key, or 0 if this key has a name.

getName

public String getName()

Returns:

the name associated with this key, or null if this key has an id

getKind

public String getKind()

Returns:

the low-level datastore kind associated with this Key

getParent

public <V> Key<V> getParent()

Returns:

the parent key, or null if there is no parent. Note that the parent could potentially have any type.

getRoot

public <V> Key<V> getRoot()

Gets the root of a parent graph of keys. If a Key has no parent, it is the root.

Returns:

the topmost parent key, or this object itself if it is the root. Note that the root key could potentially have any type.

compareTo

public int compareTo(Key<?> other)

Compares based on comparison of the raw key

Specified by:

compareTo in interface Comparable<Key<?>>

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

equivalent

public boolean equivalent(Key<T> other)

A type-safe equivalence comparison

equivalent

public boolean equivalent(Ref<T> other)

A type-safe equivalence comparison

hashCode

public int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Creates a human-readable version of this key

Overrides:

toString in class Object

getString

public String getString()

Call KeyFactory.keyToString() on the underlying Key. You can reconstitute a Key using the constructor that takes a websafe string.

key

public static <V> Key<V> key(com.google.appengine.api.datastore.Key raw)

Easy null-safe conversion of the raw key.

key

public static com.google.appengine.api.datastore.Key key(Key<?> typed)

Easy null-safe conversion of the typed key.

getKind

public static String getKind(Class<?> clazz)

Determines the kind for a Class, as understood by the datastore. The first class in a hierarchy that has @Entity defines the kind (either explicitly or as that class' simplename).

Throws:

IllegalArgumentException - if a kind cannot be determined (ie no @Entity in hierarchy).