Module org.hdfgroup.object

Package hdf.object.h5

Class H5Group

Object

hdf.object.HObject

hdf.object.Group

hdf.object.h5.H5Group

All Implemented Interfaces:

MetaDataContainer, Serializable

public class H5Group
extends Group

An H5Group object represents an existing HDF5 group in file. In HDF5, every object has at least one name. An HDF5 group is used to store a set of the names together in one place, i.e. a group. The general structure of a group is similar to that of the UNIX file system in that the group may contain references to other groups or data objects just as the UNIX directory may contain sub-directories or files. For more information on HDF5 Groups, HDF5 User's Guide

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
H5Group(FileFormat theFile, String theName, String thePath, Group theParent)	Constructs an HDF5 group with specific name, path, and parent.
H5Group(FileFormat theFile, String theName, String thePath, Group theParent, long[] oid)	Deprecated. Not for public use in the future. Using H5Group(FileFormat, String, String, Group)

Method Summary

Modifier and Type	Method	Description
void	clear()	Removes all of the elements from metadata list.
void	close(long gid)	Closes access to the object.
static H5Group	create(String name, Group pgroup, long... gplist)	Creates a new group with a name in a group and with the group creation properties specified in gplist.
List<Attribute>	getMetadata()	Retrieves the object's metadata, such as attributes, from the file.
List<Attribute>	getMetadata(int... attrPropList)	Retrieves the object's metadata, such as attributes, from the file.
int	getNumberOfMembersInFile()	Returns the total number of members of this group in file.
long[]	getToken()	Get the token for this object.
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	setName(String newName)	Sets the name of the group.
void	setPath(String newPath)	Sets the path of the 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, depthFirstMemberList, getMember, getMemberList, getParent, isRoot, removeFromMemberList

Methods inherited from class hdf.object.HObject

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

Methods inherited from class java.lang.Object

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

Constructor Details

H5Group

public H5Group(FileFormat theFile,
 String theName,
 String thePath,
 Group theParent)

Constructs an HDF5 group with specific name, path, and parent.

Parameters:

theFile - the file that contains the group.

theName - the name of this group, e.g. "grp01".

thePath - the full path of this group, e.g. "/groups/".

theParent - the parent of this group.

H5Group

@Deprecated
public H5Group(FileFormat theFile,
 String theName,
 String thePath,
 Group theParent,
 long[] oid)

Deprecated.

Not for public use in the future.
Using H5Group(FileFormat, String, String, Group)

Parameters:

theFile - the file that contains the group.

theName - the name of this group, e.g. "grp01".

thePath - the full path of this group, e.g. "/groups/".

theParent - the parent of this group.

oid - the oid of this group.

Method Details

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 gid)

Description copied from class: HObject

Closes access to the object. Sub-classes must implement this interface because different data objects have their own ways of how the data resources are closed. For example, H5Group.close() calls the hdf.hdf5lib.H5.H5Gclose() method and closes the group resource specified by the group id.

Specified by:

close in class HObject

Parameters:

gid - The object identifier.

getToken

public long[] getToken()

Get the token for this object.

Returns:

true if it has any attributes, false otherwise.

hasAttribute

public boolean hasAttribute()

Check if the object has any attributes attached.

Returns:

true if it has any attributes, false otherwise.

getNumberOfMembersInFile

public int getNumberOfMembersInFile()

Description copied from class: Group

Returns the total number of members of this group in file. Current Java applications such as HDFView cannot handle files with large numbers of objects (1,000,000 or more objects) due to JVM memory limitation. The max_members is used so that applications such as HDFView will load up to max_members number of objects. If the number of objects in file is larger than max_members, only max_members are loaded in memory. getNumberOfMembersInFile() returns the number of objects in this group. The number of objects in memory is obtained by getMemberList().size().

Overrides:

getNumberOfMembersInFile in class Group

Returns:

Total number of members of this group in the file.

clear

public void clear()

Removes all of the elements from metadata list. The list should be empty after this call returns.

Specified by:

clear in interface MetaDataContainer

Overrides:

clear in class Group

getMetadata

public List<Attribute> getMetadata()
                            throws hdf.hdf5lib.exceptions.HDF5Exception

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.hdf5lib.exceptions.HDF5Exception - if the metadata can not be retrieved

getMetadata

public List<Attribute> getMetadata(int... attrPropList)
                            throws hdf.hdf5lib.exceptions.HDF5Exception

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:

hdf.hdf5lib.exceptions.HDF5Exception - 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.hdf5lib.exceptions.HDF5Exception

Deletes an existing piece of metadata from this object.

Parameters:

info - the metadata to delete.

Throws:

hdf.hdf5lib.exceptions.HDF5Exception - if the metadata can not be removed

updateMetadata

public void updateMetadata(Object info)
                    throws hdf.hdf5lib.exceptions.HDF5Exception

Updates an existing piece of metadata attached to this object.

Parameters:

info - the metadata to update.

Throws:

hdf.hdf5lib.exceptions.HDF5Exception - if the metadata can not be updated

setName

public void setName(String newName)
             throws Exception

Description copied from class: Group

Sets the name of the group. setName (String newName) changes the name of the group in memory and file. setName() updates the path in memory for all the objects that are under the group with the new name.

Overrides:

setName in class Group

Parameters:

newName - The new name of the group.

Throws:

Exception - if the name can not be set

setPath

public void setPath(String newPath)
             throws Exception

Description copied from class: HObject

Sets the path of the object. setPath() is needed to change the path for an object when the name of a group containing the object is changed by setName(). The path of the object in memory under this group should be updated to the new path to the group. Unlike setName(), setPath() does not change anything in file.

Overrides:

setPath in class HObject

Parameters:

newPath - The new path of the object.

Throws:

Exception - if a failure occurred

create

public static H5Group create(String name,
 Group pgroup,
 long... gplist)
                      throws Exception

Creates a new group with a name in a group and with the group creation properties specified in gplist. The gplist contains a sequence of group creation property list identifiers, lcpl, gcpl, gapl. It allows the user to create a group with group creation properties. It will close the group creation properties specified in gplist.

Parameters:

name - The name of a new group.

pgroup - The parent group object.

gplist - The group creation properties, in which the order of the properties conforms the HDF5 library API, H5Gcreate(), i.e. lcpl, gcpl and gapl, where

• lcpl : Property list for link creation
• gcpl : Property list for group creation
• gapl : Property list for group access

Returns:

The new group if successful; otherwise returns null.

Throws:

Exception - if there is a failure.

See Also:

• for the order of property list identifiers.