javax.jdo.identity
Class SingleFieldIdentity

java.lang.Object
  extended by javax.jdo.identity.SingleFieldIdentity
All Implemented Interfaces:
java.io.Externalizable, java.io.Serializable, java.lang.Comparable
Direct Known Subclasses:
ByteIdentity, CharIdentity, IntIdentity, LongIdentity, ObjectIdentity, ShortIdentity, StringIdentity

public abstract class SingleFieldIdentity
extends java.lang.Object
implements java.io.Externalizable, java.lang.Comparable

This class is the abstract base class for all single field identity classes. A common case of application identity uses exactly one persistent field in the class to represent identity. In this case, the application can use a standard JDO class instead of creating a new user-defined class for the purpose.

Version:
2.0
See Also:
Serialized Form

Constructor Summary
SingleFieldIdentity()
          Constructor only for Externalizable.
 
Method Summary
 boolean equals(java.lang.Object obj)
          Check the class and class name and object type.
 java.lang.Object getKeyAsObject()
          Return the key as an Object.
 java.lang.Class getTargetClass()
          Return the target class.
 java.lang.String getTargetClassName()
          Return the target class name.
 int hashCode()
          Return the cached hash code.
 void readExternal(java.io.ObjectInput in)
          Read from the input stream.
 void writeExternal(java.io.ObjectOutput out)
          Write to the output stream.
 
Methods inherited from class java.lang.Object
getClass, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface java.lang.Comparable
compareTo
 

Constructor Detail

SingleFieldIdentity

public SingleFieldIdentity()
Constructor only for Externalizable.

Since:
2.0
Method Detail

getTargetClass

public java.lang.Class getTargetClass()
Return the target class.

Returns:
the target class.
Since:
2.0

getTargetClassName

public java.lang.String getTargetClassName()
Return the target class name.

Returns:
the target class name.
Since:
2.0

getKeyAsObject

public java.lang.Object getKeyAsObject()
Return the key as an Object. The method is synchronized to avoid race conditions in multi-threaded environments.

Returns:
the key as an Object.
Since:
2.0

equals

public boolean equals(java.lang.Object obj)
Check the class and class name and object type. If restored from serialization, class will be null so compare class name.

Overrides:
equals in class java.lang.Object
Parameters:
obj - the other object
Returns:
true if the class or class name is the same

hashCode

public int hashCode()
Return the cached hash code.

Overrides:
hashCode in class java.lang.Object
Returns:
the cached hash code.

writeExternal

public void writeExternal(java.io.ObjectOutput out)
                   throws java.io.IOException
Write to the output stream.

Specified by:
writeExternal in interface java.io.Externalizable
Parameters:
out - the stream
Throws:
java.io.IOException

readExternal

public void readExternal(java.io.ObjectInput in)
                  throws java.io.IOException,
                         java.lang.ClassNotFoundException
Read from the input stream. Creates a new instance with the target class name set

Specified by:
readExternal in interface java.io.Externalizable
Throws:
java.io.IOException
java.lang.ClassNotFoundException