Module org.hdfgroup.object

Package hdf.object.h4

Class H4Group

Object

hdf.object.HObject

hdf.object.Group

hdf.object.h4.H4Group

All Implemented Interfaces:

MetaDataContainer, Serializable

public class H4Group
extends Group

An H4Group is a vgroup in HDF4, inheriting from Group. A vgroup is a structure designed to associate related data objects. The general structure of a vgroup is similar to that of the UNIX file system in that the vgroup may contain references to other vgroups or HDF data objects just as the UNIX directory may contain subdirectories or files.

Version:

1.1 9/4/2007

Author:

Peter X. Cao

See Also:

• Serialized Form

Field Summary

Fields inherited from class hdf.object.Group

CRT_ORDER_INDEXED, CRT_ORDER_TRACKED, LINK_TYPE_EXTERNAL, LINK_TYPE_HARD, LINK_TYPE_SOFT, nMembersInFile, parent

Fields inherited from class hdf.object.HObject

fileFormat, linkTargetObjName, oid, SEPARATOR

Constructor Summary

Constructors

Constructor	Description
H4Group(FileFormat theFile, String name, String path, Group parent)	Creates a group object with specific name, path, and parent.
H4Group(FileFormat theFile, String name, String path, Group parent, long[] oid)	Creates a group object with specific name, path, parent and oid.

Method Summary

Modifier and Type	Method	Description
void	close(long vgid)	close group access.
static H4Group	create(String name, Group pgroup)	Creates a new group.
List	getMetadata()	Retrieves the object's metadata, such as attributes, from the file.
List	getMetadata(int... attrPropList)	Retrieves the object's metadata, such as attributes, from the file.
boolean	hasAttribute()	Check if the object has any attributes attached.
long	open()	Opens an existing object such as a dataset or group for access.
void	removeMetadata(Object info)	Deletes an existing piece of metadata from this object.
void	updateMetadata(Object info)	Updates an existing piece of metadata attached to this object.
void	writeMetadata(Object info)	Writes a specific piece of metadata (such as an attribute) into the file.

Methods inherited from class hdf.object.Group

addToMemberList, breadthFirstMemberList, clear, depthFirstMemberList, getMember, getMemberList, getNumberOfMembersInFile, getParent, isRoot, removeFromMemberList, setName

Methods inherited from class hdf.object.HObject

createFullname, debug, equals, equals, equalsOID, getFID, getFile, getFileFormat, getFullName, getLinkTargetObjName, getName, getOID, getPath, hashCode, setFullname, setLinkTargetObjName, setPath, toString

Methods inherited from class java.lang.Object

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

Constructor Details

H4Group

public H4Group(FileFormat theFile,
 String name,
 String path,
 Group parent)

Creates a group object with specific name, path, and parent.

Parameters:

theFile - the HDF file.

name - the name of this group.

path - the full path of this group.

parent - the parent of this group.

H4Group

public H4Group(FileFormat theFile,
 String name,
 String path,
 Group parent,
 long[] oid)

Creates a group object with specific name, path, parent and oid.

Parameters:

theFile - the HDF file.

name - the name of this group.

path - the full path of this group.

parent - the parent of this group.

oid - the unique identifier of this data object.

Method Details

hasAttribute

public boolean hasAttribute()

Description copied from interface: MetaDataContainer

Check if the object has any attributes attached.

Returns:

true if it has any attributes, false otherwise.

getMetadata

public List getMetadata()
                 throws hdf.hdflib.HDFException

Retrieves the object's metadata, such as attributes, from the file. Metadata, such as attributes, is stored in a List.

Returns:

the list of metadata objects.

Throws:

hdf.hdflib.HDFException - if the metadata can not be retrieved

writeMetadata

public void writeMetadata(Object info)
                   throws Exception

Writes a specific piece of metadata (such as an attribute) into the file. If an HDF(4&5) attribute exists in the file, this method updates its value. If the attribute does not exist in the file, it creates the attribute in the file and attaches it to the object. It will fail to write a new attribute to the object where an attribute with the same name already exists. To update the value of an existing attribute in the file, one needs to get the instance of the attribute by getMetadata(), change its values, then use writeMetadata() to write the value.

Parameters:

info - the metadata to write.

Throws:

Exception - if the metadata can not be written

removeMetadata

public void removeMetadata(Object info)
                    throws hdf.hdflib.HDFException

Deletes an existing piece of metadata from this object.

Parameters:

info - the metadata to delete.

Throws:

hdf.hdflib.HDFException - if the metadata can not be removed

updateMetadata

public void updateMetadata(Object info)
                    throws Exception

Updates an existing piece of metadata attached to this object.

Parameters:

info - the metadata to update.

Throws:

Exception - if the metadata can not be updated

open

public long open()

Description copied from class: HObject

Opens an existing object such as a dataset or group for access. The return value is an object identifier obtained by implementing classes such as H5.H5Dopen(). This function is needed to allow other objects to be able to access the object. For instance, H5File class uses the open() function to obtain object identifier for copyAttributes(long src_id, long dst_id) and other purposes. The open() function should be used in pair with close(long) function.

Specified by:

open in class HObject

Returns:

the object identifier if successful; otherwise returns a negative value.

See Also:

• HObject.close(long)

close

public void close(long vgid)

close group access.

Specified by:

close in class HObject

Parameters:

vgid - The object identifier.

create

public static H4Group create(String name,
 Group pgroup)
                      throws Exception

Creates a new group.

Parameters:

name - the name of the group to create.

pgroup - the parent group of the new group.

Returns:

the new group if successful. Otherwise returns null.

Throws:

Exception - if the group can not be created

getMetadata

public List getMetadata(int... attrPropList)
                 throws Exception

Retrieves the object's metadata, such as attributes, from the file. Metadata, such as attributes, is stored in a List.

Parameters:

attrPropList - the list of properties to get

Returns:

the list of metadata objects.

Throws:

Exception - if the metadata can not be retrieved