wt.fc
Class QueryResult

java.lang.Object
  wt.fc.QueryResult

All Implemented Interfaces:

Enumeration, Externalizable, Serializable

Direct Known Subclasses:

PagingQueryResult

public class QueryResult

extends Object

implements Enumeration, Externalizable

The QueryResult class is a container of results returned from a query. Normally, these results are accessed via the Enumeration interface which is implemented by this class. The Enumeration interface provides generic access to elements of type Object. The actual runtime type for the element is based on the type of query that is performed. For simple queries using the QuerySpec where only a single class is specified in the constructor, the element type will be Persistable. For all other queries, the safest assumption is to consider the element type to be an Object array (i.e. Object[]). In the Windchill Object-to-Relational mapping, an element in the Enumeration corresponds to a row in the result set of the query. In general, multiple classes can be specified in the query so each Object is returned as an array indexed value.

An instance of this object will internally reference each item returned from a query. When processing very large result sets, this could lead to performance issues. To handle processing large results sets, the getEnumeration() method can be called to return an Enumeration which will internally "free" references as each element is returned. This will allow the result objects to be garbage collected as soon as the object is processed and no other external references exist. When using this technique, it is important to remove (e.g. set to null) any references to the QueryResult itself, after the getEnumeration() method is called.

Supported API: true

Extendable: false

See Also:

Serialized Form

Nested Class Summary

(package private) static class	QueryResult.ChunkedExternalization Class used when streaming large results set to overcome scalability limitations of object streams by resetting stream at reasonable intervals.
(package private) static class	QueryResult.DuplicateStringEliminator Class used to eliminate duplicate strings from large query result stream.

Field Summary

private ObjectVectorIfc	anOV
private static int	CHUNK_SIZE
private static String	CLASSNAME
private Enumeration	e
static long	EXTERNALIZATION_VERSION_UID
protected static long	OLD_FORMAT_VERSION_UID
private static String	RESOURCE
(package private) static long	serialVersionUID

Constructor Summary

QueryResult()


Supported API: false

QueryResult(ObjectVectorIfc v)


Supported API: false

Method Summary

void	append(ObjectVectorIfc ov) Supported API: false
void	appendObjectVector(ObjectVector ov) Deprecated.
Enumeration	getEnumeration() Returns an Enumeration of the results optimized to remove references to elements as they are returned.
ObjectVector	getObjectVector() Deprecated. Replaced by getObjectVectorIfc()
ObjectVectorIfc	getObjectVectorIfc() Returns an ObjectVector of the results.
boolean	hasMoreElements() Indicates if more elements are available for this enumeration of the results.
Object	nextElement() Returns the next element in this enumeration of the results.
void	readExternal(ObjectInput input) Reads the non-transient fields of this class from an external source.
private boolean	readOldVersion(ObjectInput input, long readSerialVersionUID, boolean passThrough, boolean superDone) Reads the non-transient fields of this class from an external source, which is not the current version.
protected boolean	readVersion(QueryResult thisObject, ObjectInput input, long readSerialVersionUID, boolean passThrough, boolean superDone) Reads the non-transient fields of this class from an external source.
Enumeration	reset() Reset the enumeration to start of set.
int	size() Answer the number of objects in the result set.
void	writeExternal(ObjectOutput output) Writes the non-transient fields of this class to an external source.

Methods inherited from class java.lang.Object

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

Field Detail

RESOURCE

private static final String RESOURCE

See Also:

Constant Field Values

CLASSNAME

private static final String CLASSNAME

serialVersionUID

static final long serialVersionUID

See Also:

Constant Field Values

EXTERNALIZATION_VERSION_UID

public static final long EXTERNALIZATION_VERSION_UID

See Also:

Constant Field Values

OLD_FORMAT_VERSION_UID

protected static final long OLD_FORMAT_VERSION_UID

See Also:

Constant Field Values

CHUNK_SIZE

private static int CHUNK_SIZE

anOV

private ObjectVectorIfc anOV

e

private transient Enumeration e

Constructor Detail

QueryResult

public QueryResult()

Supported API: false

QueryResult

public QueryResult(ObjectVectorIfc v)

Supported API: false

Method Detail

writeExternal

public void writeExternal(ObjectOutput output)
                   throws IOException

Writes the non-transient fields of this class to an external source.

Supported API: false

Specified by:

writeExternal in interface Externalizable

Parameters:

output -

Throws:

IOException

readExternal

public void readExternal(ObjectInput input)
                  throws IOException,
                         ClassNotFoundException

Reads the non-transient fields of this class from an external source.

Supported API: false

Specified by:

readExternal in interface Externalizable

Parameters:

input -

Throws:

IOException

ClassNotFoundException

readVersion

protected boolean readVersion(QueryResult thisObject,
                              ObjectInput input,
                              long readSerialVersionUID,
                              boolean passThrough,
                              boolean superDone)
                       throws IOException,
                              ClassNotFoundException

Reads the non-transient fields of this class from an external source.

Supported API: false

Parameters:

thisObject -

input -

readSerialVersionUID -

passThrough -

superDone -

Returns:

boolean

Throws:

IOException

ClassNotFoundException

readOldVersion

private boolean readOldVersion(ObjectInput input,
                               long readSerialVersionUID,
                               boolean passThrough,
                               boolean superDone)
                        throws IOException,
                               ClassNotFoundException

Reads the non-transient fields of this class from an external source, which is not the current version.

Parameters:

input -

readSerialVersionUID -

passThrough -

superDone -

Returns:

boolean

Throws:

IOException

ClassNotFoundException

size

public int size()

Answer the number of objects in the result set.

Supported API: true

Returns:

size

reset

public Enumeration reset()

Reset the enumeration to start of set.

Supported API: true

Returns:

Enumeration of objects

getEnumeration

public Enumeration getEnumeration()

Returns an Enumeration of the results optimized to remove references to elements as they are returned. For very large results sets, this method can improve performance by allowing the elements to be garbage collected as soon as the object is processed and no other external references exist. When using this method, it is important to remove (e.g. set to null) any references to the QueryResult itself after this method is called.

Supported API: true

Returns:

Enumeration of objects

hasMoreElements

public boolean hasMoreElements()

Indicates if more elements are available for this enumeration of the results.

Supported API: true

Specified by:

hasMoreElements in interface Enumeration

Returns:

true if more elements are available

nextElement

public Object nextElement()

Returns the next element in this enumeration of the results.

Supported API: true

Specified by:

nextElement in interface Enumeration

Returns:

next result object

getObjectVectorIfc

public ObjectVectorIfc getObjectVectorIfc()

Returns an ObjectVector of the results.

Supported API: true

getObjectVector

public ObjectVector getObjectVector()

Deprecated. Replaced by getObjectVectorIfc()

Supported API: false

appendObjectVector

public void appendObjectVector(ObjectVector ov)

Deprecated.

Supported API: false

append

public void append(ObjectVectorIfc ov)

Supported API: false