com.davisor.data.stream
Class EnumeratorDataStream

java.lang.Object
  com.davisor.data.VoidData
      com.davisor.data.stream.EnumeratorDataStream

All Implemented Interfaces:

Data, DataStream

Direct Known Subclasses:

EnumeratorTypeStream

public class EnumeratorDataStream

extends VoidData

implements DataStream

EnumeratorDataStream represents a data stream that uses a standard Java enumerator to implement a stream of elements. The elements may or may not be DataValues, and they may or may not be of a mutually equal type. The stream itself has a single type, however.

References to DataValue elements are returned as they are. Elements not of the expected type are converted, first to data objects of the proper type, and then the converted objects are returned. The original objects in the source are not changed.

Since:

JDK1.1

See Also:

next(), IteratorDataStream, Type

Field Summary

protected DataValue	M_data Reference to the next data element to be returned.
protected java.util.Enumeration	M_enumerator Underlying stream enumerator.
protected long	M_index Element id counter.
protected java.lang.Object	M_metaData Stream meta data (may be null).
protected boolean	M_next Flag that tells if there still is data in this stream.

Fields inherited from class com.davisor.data.VoidData

M_type

Fields inherited from interface com.davisor.data.stream.DataStream

INITIAL_INDEX

Constructor Summary

EnumeratorDataStream(java.util.Enumeration enumerator)
Creates a data stream out of an enumerator.

EnumeratorDataStream(java.util.Enumeration enumerator, Type type)
Creates a data stream out of an enumerator and the given type.

Method Summary

boolean	close() Dummy implementation.
long	getIndex() Retrieves the index number of the element returned by the latest next() call.
boolean	hasNext() Tests if the stream still contains data.
DataValue	next() Gets the next data value from the stream.

Methods inherited from class com.davisor.data.VoidData

equals, getDataValue, getType, hashCode, setType, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface com.davisor.data.Data

getType

Field Detail

M_data

protected DataValue M_data

Reference to the next data element to be returned.

M_enumerator

protected java.util.Enumeration M_enumerator

Underlying stream enumerator.

M_index

protected long M_index

Element id counter.

M_next

protected boolean M_next

Flag that tells if there still is data in this stream.

M_metaData

protected java.lang.Object M_metaData

Stream meta data (may be null).

Constructor Detail

EnumeratorDataStream

public EnumeratorDataStream(java.util.Enumeration enumerator)
                     throws InvalidDataException

Creates a data stream out of an enumerator. The data stream type is set to AutoType.

Throws:

InvalidDataException - if the first element was not a DataValue, and no suitable type could be created for it

See Also:

EnumeratorDataStream(Enumeration,Type)

EnumeratorDataStream

public EnumeratorDataStream(java.util.Enumeration enumerator,
                            Type type)
                     throws InvalidDataException

Creates a data stream out of an enumerator and the given type.

Throws:

InvalidDataException - if the first element is not of the given type and cannot be converted to a data object of that type

See Also:

EnumeratorDataStream(Enumeration)

Method Detail

close

public boolean close()

Dummy implementation.

Specified by:

close in interface DataStream

Returns:

if stream closing was successfull or not

See Also:

DataStream.hasNext()

getIndex

public long getIndex()

Retrieves the index number of the element returned by the latest next() call. The index represents the position of the element within this stream. The stream index may or may not be equal to any other indexes the element itself thinks it posesses.

The index value is initially -1, indicating no element. After first next() call, index becomes 0, then 1, and so on. This functionality resembles java.sql.resultSet#getRow method functionality, but with the difference that the index counter starts from 0, not 1.

Specified by:

getIndex in interface DataStream

Returns:

element index

hasNext

public boolean hasNext()

Tests if the stream still contains data.

Specified by:

hasNext in interface DataStream

Returns:

true if it does.

next

public DataValue next()
               throws InvalidDataException

Gets the next data value from the stream.

Specified by:

next in interface DataStream

Throws:

InvalidDataException - if the stream content does not satisfy the stream type.