Oracle® Coherence Java API Reference
v3.5

E14977-01

com.tangosol.util
Class NullImplementation.NullValueExtractor

java.lang.Object
  extended by com.tangosol.util.NullImplementation.NullValueExtractor
All Implemented Interfaces:
ExternalizableLite, PortableObject, ValueExtractor, java.io.Serializable
Enclosing class:
NullImplementation

public static class NullImplementation.NullValueExtractor
extends java.lang.Object
implements ValueExtractor, java.io.Serializable, ExternalizableLite, PortableObject

A ValueExtractor that always results in the passed-in value.


Field Summary
static NullImplementation.NullValueExtractor INSTANCE
          Since the ValueExtractor contains no information, only one ever has to exist.
 
Constructor Summary
NullImplementation.NullValueExtractor()
          Default constructor (for ExternalizableLite and PortableObject).
 
Method Summary
 boolean equals(java.lang.Object o)
          Compare the ValueExtractor with another object to determine equality.
 java.lang.Object extract(java.lang.Object o)
          Extract the value from the passed object.
 int hashCode()
          Determine a hash value for the ValueExtractor object according to the general Object.hashCode() contract.
 void readExternal(java.io.DataInput in)
          Restore the contents of this object by loading the object's state from the passed DataInput object.
 void readExternal(PofReader in)
          Restore the contents of a user type instance by reading its state using the specified PofReader object.
 java.lang.String toString()
          Provide a human-readable description of this ValueExtractor object.
 void writeExternal(java.io.DataOutput out)
          Save the contents of this object by storing the object's state into the passed DataOutput object.
 void writeExternal(PofWriter out)
          Save the contents of a POF user type instance by writing its state using the specified PofWriter object.
 

Field Detail

INSTANCE

public static final NullImplementation.NullValueExtractor INSTANCE
Since the ValueExtractor contains no information, only one ever has to exist.

Constructor Detail

NullImplementation.NullValueExtractor

public NullImplementation.NullValueExtractor()
Default constructor (for ExternalizableLite and PortableObject).

Method Detail

extract

public java.lang.Object extract(java.lang.Object o)
Extract the value from the passed object. The returned value may be null. For intrinsic types, the returned value is expected to be a standard wrapper type in the same manner that reflection works; for example, int would be returned as a java.lang.Integer.

Specified by:
extract in interface ValueExtractor
Parameters:
o - an Object to retrieve the value from
Returns:
the extracted value as an Object; null is an acceptable value
Throws:
java.lang.ClassCastException - if this ValueExtractor is incompatible with the passed object to extract a value from and the implementation requires the passed object to be of a certain type
WrapperException - if this ValueExtractor encounters an exception in the course of extracting the value
java.lang.IllegalArgumentException - if this ValueExtractor cannot handle the passed object for any other reason; an implementor should include a descriptive message

equals

public boolean equals(java.lang.Object o)
Compare the ValueExtractor with another object to determine equality. Two ValueExtractor objects, ve1 and ve2 are considered equal iff ve1.extract(o) equals ve2.extract(o) for all values of o.

Specified by:
equals in interface ValueExtractor
Parameters:
o - the reference object with which to compare
Returns:
true iff this ValueExtractor and the passed object are equivalent ValueExtractors

hashCode

public int hashCode()
Determine a hash value for the ValueExtractor object according to the general Object.hashCode() contract.

Specified by:
hashCode in interface ValueExtractor
Returns:
an integer hash value for this ValueExtractor object

toString

public java.lang.String toString()
Provide a human-readable description of this ValueExtractor object.

Specified by:
toString in interface ValueExtractor
Returns:
a human-readable description of this ValueExtractor object

readExternal

public void readExternal(java.io.DataInput in)
                  throws java.io.IOException
Restore the contents of this object by loading the object's state from the passed DataInput object.

Specified by:
readExternal in interface ExternalizableLite
Parameters:
in - the DataInput stream to read data from in order to restore the state of this object
Throws:
java.io.IOException - if an I/O exception occurs
java.io.NotActiveException - if the object is not in its initial state, and therefore cannot be deserialized into

writeExternal

public void writeExternal(java.io.DataOutput out)
                   throws java.io.IOException
Save the contents of this object by storing the object's state into the passed DataOutput object.

Specified by:
writeExternal in interface ExternalizableLite
Parameters:
out - the DataOutput stream to write the state of this object to
Throws:
java.io.IOException - if an I/O exception occurs

readExternal

public void readExternal(PofReader in)
                  throws java.io.IOException
Restore the contents of a user type instance by reading its state using the specified PofReader object.

Specified by:
readExternal in interface PortableObject
Parameters:
in - the PofReader from which to read the object's state
Throws:
java.io.IOException - if an I/O error occurs

writeExternal

public void writeExternal(PofWriter out)
                   throws java.io.IOException
Save the contents of a POF user type instance by writing its state using the specified PofWriter object.

Specified by:
writeExternal in interface PortableObject
Parameters:
out - the PofWriter to which to write the object's state
Throws:
java.io.IOException - if an I/O error occurs

Oracle® Coherence Java API Reference
v3.5

E14977-01

Copyright © 2000, 2009, Oracle. All rights reserved.