ncsa.hdf.object.h5
Class H5Group

java.lang.Object
  ncsa.hdf.object.HObject
      ncsa.hdf.object.Group
          ncsa.hdf.object.h5.H5Group

All Implemented Interfaces:

java.io.Serializable, DataFormat

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,

Version:

1.1 9/4/2007

Author:

Peter X. Cao

See Also:

HDF5 User's Guide

, Serialized Form

Field Summary

static long

serialVersionUID

Fields inherited from class ncsa.hdf.object.Group

CRT_ORDER_INDEXED, CRT_ORDER_TRACKED, LINK_TYPE_EXTERNAL, LINK_TYPE_HARD, LINK_TYPE_SOFT

Fields inherited from class ncsa.hdf.object.HObject

separator

Constructor Summary

H5Group(FileFormat theFile, java.lang.String name, java.lang.String path, Group parent)
Constructs an HDF5 group with specific name, path, and parent.

H5Group(FileFormat theFile, java.lang.String name, java.lang.String path, Group parent, long[] oid)
Deprecated. Not for public use in the future.
Using H5Group(FileFormat, String, String, Group)

Method Summary

void	clear() Clears up member list and other resources in memory for the group.
void	close(int gid) Closes access to the object.
static H5Group	create(java.lang.String name, Group pgroup, int... gplist) Creates a new group with a name in a group and with the group creation properties specified in gplist.
java.util.List	getMetadata() Retrieves the metadata such as attributes from file.
java.util.List	getMetadata(int... attrPropList)
int	getNumberOfMembersInFile() Returns the total number of members of this group in file.
boolean	hasAttribute() Check if the object has any attributes attached.
int	open() Opens an existing object such as dataset or group for access.
void	removeMetadata(java.lang.Object info) Deletes an existing metadata from this data object.
void	setName(java.lang.String newName) Sets the name of the group.
void	setPath(java.lang.String newPath) Sets the path of the object.
void	writeMetadata(java.lang.Object info) Writes a specific metadata (such as attribute) into file.

Methods inherited from class ncsa.hdf.object.Group

addToMemberList, getMemberList, getParent, isRoot, removeFromMemberList

Methods inherited from class ncsa.hdf.object.HObject

equalsOID, getFID, getFile, getFileFormat, getFullName, getLinkTargetObjName, getName, getOID, getPath, setLinkTargetObjName, toString

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

serialVersionUID

public static final long serialVersionUID

See Also:

HObject.serialVersionUID, Constant Field Values

Constructor Detail

H5Group

public H5Group(FileFormat theFile,
               java.lang.String name,
               java.lang.String path,
               Group parent)

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

Parameters:

theFile - the file which containing the group.

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

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

parent - the parent of this group.

H5Group

@Deprecated
public H5Group(FileFormat theFile,
                          java.lang.String name,
                          java.lang.String path,
                          Group parent,
                          long[] oid)

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

Method Detail

hasAttribute

public boolean hasAttribute()

Description copied from interface: DataFormat

Check if the object has any attributes attached.

Returns:

true if it has any attribute(s), false otherwise.

getNumberOfMembersInFile

public int getNumberOfMembersInFile()

Description copied from class: Group

Returns the total number of members of this group in file. Current Java application 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()

Description copied from class: Group

Clears up member list and other resources in memory for the group. Since the destructor will clear memory space, the function is usually not needed.

Overrides:

clear in class Group

getMetadata

public java.util.List getMetadata()
                           throws HDF5Exception

Description copied from interface: DataFormat

Retrieves the metadata such as attributes from file.

Metadata such as attributes are stored in a List.

Returns:

the list of metadata objects.

Throws:

HDF5Exception

getMetadata

public java.util.List getMetadata(int... attrPropList)
                           throws HDF5Exception

Throws:

HDF5Exception

writeMetadata

public void writeMetadata(java.lang.Object info)
                   throws java.lang.Exception

Description copied from interface: DataFormat

Writes a specific metadata (such as attribute) into file.

If an HDF(4&5) attribute exists in file, the method updates its value. If the attribute does not exists in file, it creates the attribute in 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 file, one needs to get the instance of the attribute by getMetadata(), change its values, and use writeMetadata() to write the value.

Parameters:

info - the metadata to write.

Throws:

java.lang.Exception

removeMetadata

public void removeMetadata(java.lang.Object info)
                    throws HDF5Exception

Description copied from interface: DataFormat

Deletes an existing metadata from this data object.

Parameters:

info - the metadata to delete.

Throws:

HDF5Exception

open

public int open()

Description copied from class: HObject

Opens an existing object such as 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(int src_id, int dst_id) and other purposes. The open() function should be used in pair with close(int) function.

Specified by:

open in class HObject

Returns:

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

See Also:

HObject.close(int)

close

public void close(int 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 ncsa.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.

create

public static H5Group create(java.lang.String name,
                             Group pgroup,
                             int... gplist)
                      throws java.lang.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.

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:

java.lang.Exception

See Also:

for the order of property list identifiers.

setName

public void setName(java.lang.String newName)
             throws java.lang.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:

java.lang.Exception

setPath

public void setPath(java.lang.String newPath)
             throws java.lang.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 conatining 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:

java.lang.Exception