com.davisor.data.stream
Class LazyListDataBuffer

java.lang.Object
  com.davisor.data.VoidData
      com.davisor.data.stream.CollectionDataSource
          com.davisor.data.stream.ListDataBuffer
              com.davisor.data.stream.LazyListDataBuffer

All Implemented Interfaces:

Data, DataBuffer, DataSource

public class LazyListDataBuffer

extends ListDataBuffer

LazyListDataBuffer implements a delayed initialization list data buffer. In particular, the buffer will be filled with data copied from a given data source, but only when the buffer is actually accessed the first time with a call to any of the DataBuffer interface methods.

The initialization status of lazy list data buffers can be checked with notInitialized() method which will return true until the the buffer has been initialized. Please note that an notInitialized() call will not trigger data buffer initialization.

Since:

JDK1.4

See Also:

notInitialized()

Field Summary

boolean	DEBUG debug switch
protected DataSource	M_dataSource Data buffer data source.

Fields inherited from class com.davisor.data.stream.CollectionDataSource

M_collection

Fields inherited from class com.davisor.data.VoidData

M_type

Constructor Summary

LazyListDataBuffer(DataSource dataSource)
Creates a new delayed initialization list data buffer.

Method Summary

DataValue	getData(int index) Gets the specific data element.
int	getSize() Gets the number of data in the buffer.
DataStream	getStream() Gets a new data stream from the data source.
DataStream	getStream(boolean reversed) Gets a new data stream from the data source.
Type	getType() Gets the type of this data object.
protected void	init() Delayed initializer.
boolean	notInitialized() Tests if this instance has not been initialized.
java.lang.String	toString(java.lang.String id, java.lang.String dataName) Gets XML representation for the asked channel.

Methods inherited from class com.davisor.data.stream.ListDataBuffer

getList

Methods inherited from class com.davisor.data.stream.CollectionDataSource

addAll, close, getCollection, setType, toString

Methods inherited from class com.davisor.data.VoidData

equals, getDataValue, hashCode

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.davisor.data.stream.DataSource

close

Field Detail

DEBUG

public final boolean DEBUG

debug switch

See Also:

Constant Field Values

M_dataSource

protected DataSource M_dataSource

Data buffer data source.

Constructor Detail

LazyListDataBuffer

public LazyListDataBuffer(DataSource dataSource)

Creates a new delayed initialization list data buffer.

Method Detail

getType

public Type getType()
             throws InvalidDataException

Gets the type of this data object.

Specified by:

getType in interface Data

Overrides:

getType in class VoidData

Returns:

the type associated with this data object

Throws:

InvalidDataException

getStream

public DataStream getStream()
                     throws InvalidDataException

Gets a new data stream from the data source.

Specified by:

getStream in interface DataSource

Overrides:

getStream in class CollectionDataSource

Throws:

InvalidDataException

See Also:

IteratorDataStream.IteratorDataStream(Collection,Type)

toString

public java.lang.String toString(java.lang.String id,
                                 java.lang.String dataName)

Gets XML representation for the asked channel.

Specified by:

toString in interface DataSource

Overrides:

toString in class CollectionDataSource

Parameters:

id - channel id

dataName - channel dataName

getData

public DataValue getData(int index)
                  throws com.davisor.core.InvalidIndexException

Gets the specific data element.

If current data source has not yet been consulted, it will be, now.

Specified by:

getData in interface DataBuffer

Overrides:

getData in class ListDataBuffer

Parameters:

index - data element index

Throws:

com.davisor.core.InvalidIndexException - if no data is bound to given index

See Also:

notInitialized()

getSize

public int getSize()

Gets the number of data in the buffer.

If current data source has not yet been consulted, it will be, now. If initialization fails, buffer size remains zero.

Specified by:

getSize in interface DataBuffer

Overrides:

getSize in class ListDataBuffer

See Also:

notInitialized()

getStream

public DataStream getStream(boolean reversed)
                     throws InvalidDataException

Gets a new data stream from the data source.

If current data source has not yet been consulted, it will be, now.

Specified by:

getStream in interface DataBuffer

Overrides:

getStream in class ListDataBuffer

Parameters:

reversed - controls if stream reads buffer forwards or backwards

Throws:

InvalidDataException - if a new stream can not be created

See Also:

notInitialized()

init

protected void init()
             throws InvalidDataException

Delayed initializer. This method will set object list and type, and fill the list with elements copied from current data source. Once all data from the data source has been consumed, the original data source is discarded.

Throws:

InvalidDataException

notInitialized

public boolean notInitialized()

Tests if this instance has not been initialized.

Returns:

true if this instances has not been initialized yet