com.google.appengine.tools.mapreduce.inputs

Class PeekingInputReader<T>

java.lang.Object

com.google.appengine.tools.mapreduce.InputReader<T>

com.google.appengine.tools.mapreduce.inputs.UnmarshallingInputReader<T>

com.google.appengine.tools.mapreduce.inputs.PeekingInputReader<T>

Type Parameters:

T - type of values produced by this input

All Implemented Interfaces:

Serializable, Iterator<T>

public class PeekingInputReader<T>
extends UnmarshallingInputReader<T>
implements Iterator<T>

An InputReader that allows peeking at records without consuming them.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
PeekingInputReader(InputReader<ByteBuffer> reader, Marshaller<T> marshaller)

Method Summary

Methods

Modifier and Type	Method and Description
boolean	hasNext()
T	next() The next element in the input.
T	peek() Returns the element that will be returned by next() next.
void	remove()

Methods inherited from class com.google.appengine.tools.mapreduce.inputs.UnmarshallingInputReader

beginShard, beginSlice, endShard, endSlice, estimateMemoryRequirement, getMarshaller, getProgress

Methods inherited from class com.google.appengine.tools.mapreduce.InputReader

close, getContext, open, setContext

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

PeekingInputReader

public PeekingInputReader(InputReader<ByteBuffer> reader,
                  Marshaller<T> marshaller)

Method Detail

next

public T next()
       throws NoSuchElementException

The next element in the input. (Which may or may not have been peeked)

Specified by:

next in interface Iterator<T>

Overrides:

next in class UnmarshallingInputReader<T>

Throws:

RuntimeException - In the event that reading from input fails.

NoSuchElementException - if there are no more elements in the input.

peek

public T peek()

Returns the element that will be returned by next() next. Or null if there is no next element. If null elements are allowed in the input, one can distinguish between the end of the input and a null element by calling hasNext()

Throws:

RuntimeException - In the event that reading from input fails.

hasNext

public boolean hasNext()

Specified by:

hasNext in interface Iterator<T>

remove

public void remove()

Specified by:

remove in interface Iterator<T>