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java.lang.Object org.apache.crunch.materialize.pobject.PObjectImpl<S,T>
S
- The type contained in the underlying PCollection.T
- The type encapsulated by this PObject.public abstract class PObjectImpl<S,T>
An abstract implementation of PObject
that is backed by a PCollection
.
Clients creating a concrete implementation should override the method
process(Iterable)
, which transforms the backing PCollection into the
singleton value encapsulated by the PObject. Once this {code PObject}'s value has been
calculated, the value is cached to prevent subsequent materializations of the backing
PCollection
.
Constructor Summary | |
---|---|
PObjectImpl(PCollection<S> collect)
Constructs a new instance of this PObject implementation. |
Method Summary | |
---|---|
T |
getValue()
Gets the value associated with this PObject . |
protected abstract T |
process(Iterable<S> input)
Transforms the provided Iterable, obtained from the backing PCollection ,
into the value encapsulated by this PObject . |
String |
toString()
|
Methods inherited from class java.lang.Object |
---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
Constructor Detail |
---|
public PObjectImpl(PCollection<S> collect)
PObject
implementation.
collect
- The backing PCollection
for this PObject
.Method Detail |
---|
public String toString()
toString
in class Object
public final T getValue()
PObject
. Calling this method will trigger
whatever computation is necessary to obtain the value and block until that computation
succeeds.
getValue
in interface PObject<T>
PObject
.protected abstract T process(Iterable<S> input)
PCollection
,
into the value encapsulated by this PObject
.
input
- An Iterable whose elements correspond to those of the backing PCollection
.
PObject
.
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