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Oracle® Coherence Java API Reference Release 3.6.0.0 E15725-01 |
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java.lang.Object
com.tangosol.util.Base
com.tangosol.util.BitHelper
com.tangosol.util.ExternalizableHelper
com.tangosol.util.extractor.AbstractExtractor
com.tangosol.util.extractor.KeyExtractor
public class KeyExtractor
The KeyExtractor is a special purpose ValueExtractor implementation that serves as an indicator that a query should be run against the key objects rather than the values. The major difference between the KeyExtractor and a standard ReflectionExtractor
is that when used in various EntryFilter
implementations it forces the evaluation of entry keys rather than entry values. <p/> For example, consider a key object that consists of two properties: "FirstName" and "LastName". To retrieve all keys that have a value of the "LastName" property equal to "Smith", the following query could be used:
ValueExtractor extractor = new KeyExtractor("getLastName"); Set setKeys = cache.keySet(new EqualsFilter(extractor, "Smith"));
As of Coherence 3.5, the same effect can be achieved for subclasses of the AbstractExtractor, for example:
ValueExtractor extractor = new ReflectionExtractor("getLastName", null, AbstractExtractor.KEY); Set setKeys = cache.keySet(new EqualsFilter(extractor, "Smith"));
Field Summary | |
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protected ValueExtractor |
m_extractor The underlying ValueExtractor. |
Fields inherited from class com.tangosol.util.extractor.AbstractExtractor |
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KEY, m_nTarget, VALUE |
Constructor Summary | |
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KeyExtractor() Default constructor (necessary for the ExternalizableLite and PortableObject interfaces). |
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KeyExtractor(String sMethod) Construct a KeyExtractor for a specified method name. |
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KeyExtractor(ValueExtractor extractor) Construct a KeyExtractor based on a specified ValueExtractor. |
Method Summary | |
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boolean |
equals(Object o) Compare the KeyExtractor with another object to determine equality. |
Object |
extract(Object oTarget) 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. |
ValueExtractor |
getExtractor() Obtain the underlying ValueExtractor. |
int |
hashCode() Determine a hash value for the KeyExtractor object according to the general Object.hashCode() contract. |
void |
readExternal(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. |
String |
toString() Return a human-readable description for this KeyExtractor. |
void |
writeExternal(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. |
Methods inherited from class com.tangosol.util.extractor.AbstractExtractor |
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compare, compareEntries, extractFromEntry, extractOriginalFromEntry |
Methods inherited from class com.tangosol.util.BitHelper |
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countBits, countBits, countBits, indexOfLSB, indexOfLSB, indexOfLSB, indexOfMSB, indexOfMSB, indexOfMSB, rotateLeft, rotateLeft, rotateLeft, rotateRight, rotateRight, rotateRight, toBitString, toBitString, toBitString |
Field Detail |
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protected ValueExtractor m_extractor
Constructor Detail |
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public KeyExtractor()
public KeyExtractor(ValueExtractor extractor)
extractor
- the underlying ValueExtractorpublic KeyExtractor(String sMethod)
sMethod
- a method name to construct an underlying ReflectionExtractor
for; this parameter can also be a dot-delimited sequence of method names which would result in a KeyExtractor based on the ChainedExtractor
that is based on an array of corresponding ReflectionExtractor objectsMethod Detail |
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public Object extract(Object oTarget)
extract
in interface ValueExtractor
extract
in class AbstractExtractor
oTarget
- an Object to retrieve the value frompublic ValueExtractor getExtractor()
public boolean equals(Object o)
equals
in interface ValueExtractor
equals
in interface Comparator
o
- the reference object with which to compareObject.equals(java.lang.Object)
, Object.hashCode()
public int hashCode()
Object.hashCode()
contract.hashCode
in interface ValueExtractor
public String toString()
toString
in interface ValueExtractor
public void readExternal(DataInput in) throws IOException
readExternal
in interface ExternalizableLite
in
- the DataInput stream to read data from in order to restore the state of this objectIOException
- if an I/O exception occursNotActiveException
- if the object is not in its initial state, and therefore cannot be deserialized intopublic void writeExternal(DataOutput out) throws IOException
writeExternal
in interface ExternalizableLite
out
- the DataOutput stream to write the state of this object toIOException
- if an I/O exception occurspublic void readExternal(PofReader in) throws IOException
readExternal
in interface PortableObject
in
- the PofReader from which to read the object's stateIOException
- if an I/O error occurspublic void writeExternal(PofWriter out) throws IOException
writeExternal
in interface PortableObject
out
- the PofWriter to which to write the object's stateIOException
- if an I/O error occurs
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Oracle® Coherence Java API Reference Release 3.6.0.0 E15725-01 |
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