opennlp.tools.util

Interface ObjectStream<T>

All Superinterfaces:

java.lang.AutoCloseable

All Known Subinterfaces:

SequenceStream

All Known Implementing Classes:

AbstractEventStream, AbstractObjectStream, CollectionObjectStream, CrossValidationPartitioner.TrainingSampleStream, EventTraceStream, FileEventStream, FilterObjectStream, HashSumEventStream, NameFinderEventStream, NameSampleDataStream, NameSampleSequenceStream, NameSampleTypeFilter, ParagraphStream, PlainTextByLineStream, RealBasicEventStream, RealValueFileEventStream, SequenceStreamEventStream, TokenizerStream, TokenSampleStream, TokSpanEventStream, WhitespaceTokenStream

public interface ObjectStream<T>
extends java.lang.AutoCloseable

Reads Objects from a stream.

Design Decision:
This interface provides a means for iterating over the objects in a stream, it does not implement Iterator or Iterable because:

• Iterator.next() and Iterator.hasNext() are declared as throwing no checked exceptions. Thus the IOExceptions thrown by read() would have to be wrapped in RuntimeExceptions, and the compiler would be unable to force users of this code to catch such exceptions.
• Implementing Iterable would mean either silently calling reset() to guarantee that all items were always seen on each iteration, or documenting that the Iterable only iterates over the remaining elements of the ObjectStream. In either case, users not reading the documentation carefully might run into unexpected behavior.

See Also:

ObjectStreamException

Method Summary

Modifier and Type	Method and Description
void	close() Closes the ObjectStream and releases all allocated resources.
T	read() Returns the next object.
void	reset() Repositions the stream at the beginning and the previously seen object sequence will be repeated exactly.

Method Detail

read

T read()
throws java.io.IOException

Returns the next object. Calling this method repeatedly until it returns null will return each object from the underlying source exactly once.

Returns:

the next object or null to signal that the stream is exhausted

Throws:

java.io.IOException - if there is an error during reading

reset

void reset()
    throws java.io.IOException,
           java.lang.UnsupportedOperationException

Repositions the stream at the beginning and the previously seen object sequence will be repeated exactly. This method can be used to re-read the stream if multiple passes over the objects are required. The implementation of this method is optional.

Throws:

java.io.IOException - if there is an error during reseting the stream

java.lang.UnsupportedOperationException

close

void close()
    throws java.io.IOException

Closes the ObjectStream and releases all allocated resources. After close was called its not allowed to call read or reset.

Specified by:

close in interface java.lang.AutoCloseable

Throws:

java.io.IOException - if there is an error during closing the stream