de.intarsys.tools.preferences
Class NullPreferences

java.lang.Object
  extended by de.intarsys.tools.preferences.NullPreferences
All Implemented Interfaces:
IPreferences

public class NullPreferences
extends java.lang.Object
implements IPreferences

A "null" IPreferences implementation.


Field Summary
static NullPreferences ACTIVE
           
 
Fields inherited from interface de.intarsys.tools.preferences.IPreferences
SCOPE_DEFAULT, SCOPE_GLOBAL, SCOPE_INSTALLATION, SCOPE_TEAM, SCOPE_USER
 
Constructor Summary
NullPreferences()
           
 
Method Summary
 java.lang.String absolutePath()
          Returns this preference node's absolute path name.
 IPreferences[] children()
          The array of all child preferences.
 java.lang.String[] childrenNames()
          Returns the names of the children of this preference node, relative to this node.
 void clear()
          Removes all of the preferences (key-value associations) in this preference node.
 void flush()
          Forces any changes in the contents of this preference node and its descendants to the persistent store.
 java.lang.String get(java.lang.String name)
          Returns the current value of the string-valued preference with the given name.
 java.lang.String get(java.lang.String key, java.lang.String def)
          Returns the value associated with the specified key in this preference node.
 boolean getBoolean(java.lang.String name)
          Returns the current value of the boolean-valued preference with the given name.
 boolean getBoolean(java.lang.String key, boolean def)
          Returns the boolean value represented by the string associated with the specified key in this preference node.
 byte[] getByteArray(java.lang.String key, byte[] def)
          Returns the byte array value represented by the string associated with the specified key in this preference node.
 double getDouble(java.lang.String name)
          Returns the current value of the double-valued preference with the given name.
 double getDouble(java.lang.String key, double def)
          Returns the double value represented by the string associated with the specified key in this preference node.
 float getFloat(java.lang.String name)
          Returns the current value of the float-valued preference with the given name.
 float getFloat(java.lang.String key, float def)
          Returns the float value represented by the string associated with the specified key in this preference node.
 int getInt(java.lang.String name)
          Returns the current value of the integer-valued preference with the given name.
 int getInt(java.lang.String key, int def)
          Returns the int value represented by the string associated with the specified key in this preference node.
 long getLong(java.lang.String name)
          Returns the current value of the long-valued preference with the given name.
 long getLong(java.lang.String key, long def)
          Returns the long value represented by the string associated with the specified key in this preference node.
 java.lang.String[] keys()
          Returns all of the keys that have an associated value in this preference node.
 java.lang.String name()
          Returns this preference node's name, relative to its parent.
 IPreferences node(java.lang.String pathName)
          Returns the named preference node in the same tree as this node, creating it and any of its ancestors if they do not already exist.
 boolean nodeExists(java.lang.String pathName)
          Returns true if the named preference node exists in the same tree as this node.
 IPreferences parent()
          Returns the parent of this preference node, or null if this is the root.
 java.util.Map<java.lang.String,java.lang.String> properties()
          A map of all property mappings in this IPreferences node.
 void put(java.lang.String name, boolean value)
          Sets the current value of the boolean-valued preference with the given name.
 void put(java.lang.String key, byte[] value)
          Associates a string representing the specified byte array with the specified key in this preference node.
 void put(java.lang.String name, double value)
          Sets the current value of the double-valued preference with the given name.
 void put(java.lang.String name, float value)
          Sets the current value of the float-valued preference with the given name.
 void put(java.lang.String name, int value)
          Sets the current value of the integer-valued preference with the given name.
 void put(java.lang.String name, long value)
          Sets the current value of the long-valued preference with the given name.
 void put(java.lang.String name, java.lang.String value)
          Sets the current value of the string-valued preference with the given name.
 void putBoolean(java.lang.String key, boolean value)
          Set the current value.
 void putByteArray(java.lang.String key, byte[] value)
          Set the current value.
 void putDouble(java.lang.String key, double value)
          Set the current value.
 void putFloat(java.lang.String key, float value)
          Set the current value.
 void putInt(java.lang.String key, int value)
          Set the current value.
 void putLong(java.lang.String key, long value)
          Set the current value.
 void remove(java.lang.String key)
          Removes the value associated with the specified key in this preference node, if any.
 void removeNode()
          Removes this preference node and all of its descendants, invalidating any preferences contained in the removed nodes.
 IPreferences restrict(java.lang.String scopeName)
          Create a new IPreferences object whose scopes include all scopes from the receiver before and including "scopeName".
 void sync()
          Ensures that future reads from this preference node and its descendants reflect any changes that were committed to the persistent store (from any VM) prior to the sync invocation.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

ACTIVE

public static final NullPreferences ACTIVE
Constructor Detail

NullPreferences

public NullPreferences()
Method Detail

absolutePath

public java.lang.String absolutePath()
Description copied from interface: IPreferences
Returns this preference node's absolute path name.

Specified by:
absolutePath in interface IPreferences
Returns:
this preference node's absolute path name.

children

public IPreferences[] children()
Description copied from interface: IPreferences
The array of all child preferences.

Specified by:
children in interface IPreferences
Returns:
The array of all child preferences.

childrenNames

public java.lang.String[] childrenNames()
                                 throws java.util.prefs.BackingStoreException
Description copied from interface: IPreferences
Returns the names of the children of this preference node, relative to this node. (The returned array will be of size zero if this node has no children.)

Specified by:
childrenNames in interface IPreferences
Returns:
the names of the children of this preference node.
Throws:
java.util.prefs.BackingStoreException - if this operation cannot be completed due to a failure in the backing store, or inability to communicate with it.

clear

public void clear()
           throws java.util.prefs.BackingStoreException
Description copied from interface: IPreferences
Removes all of the preferences (key-value associations) in this preference node. This call has no effect on any descendants of this node.

If this implementation supports stored defaults, and this node in the preferences hierarchy contains any such defaults, the stored defaults will be "exposed" by this call, in the sense that they will be returned by succeeding calls to get.

Specified by:
clear in interface IPreferences
Throws:
java.util.prefs.BackingStoreException - if this operation cannot be completed due to a failure in the backing store, or inability to communicate with it.
See Also:
IPreferences.removeNode()

flush

public void flush()
           throws java.util.prefs.BackingStoreException
Description copied from interface: IPreferences
Forces any changes in the contents of this preference node and its descendants to the persistent store. Once this method returns successfully, it is safe to assume that all changes made in the subtree rooted at this node prior to the method invocation have become permanent.

Implementations are free to flush changes into the persistent store at any time. They do not need to wait for this method to be called.

When a flush occurs on a newly created node, it is made persistent, as are any ancestors (and descendants) that have yet to be made persistent. Note however that any preference value changes in ancestors are not guaranteed to be made persistent.

If this method is invoked on a node that has been removed with the IPreferences.removeNode() method, flushSpi() is invoked on this node, but not on others.

Specified by:
flush in interface IPreferences
Throws:
java.util.prefs.BackingStoreException - if this operation cannot be completed due to a failure in the backing store, or inability to communicate with it.
See Also:
IPreferences.sync()

get

public java.lang.String get(java.lang.String name)
Description copied from interface: IPreferences
Returns the current value of the string-valued preference with the given name. Returns the default-default value (the empty string "" ) if there is no preference with the given name, or if the current value cannot be treated as a string.

Specified by:
get in interface IPreferences
Parameters:
name - the name of the preference
Returns:
the string-valued preference

get

public java.lang.String get(java.lang.String key,
                            java.lang.String def)
Description copied from interface: IPreferences
Returns the value associated with the specified key in this preference node. Returns the specified default if there is no value associated with the key, or the backing store is inaccessible.

Some implementations may store default values in their backing stores. If there is no value associated with the specified key but there is such a stored default, it is returned in preference to the specified default.

Specified by:
get in interface IPreferences
Parameters:
key - key whose associated value is to be returned.
def - the value to be returned in the event that this preference node has no value associated with key.
Returns:
the value associated with key, or def if no value is associated with key, or the backing store is inaccessible.

getBoolean

public boolean getBoolean(java.lang.String name)
Description copied from interface: IPreferences
Returns the current value of the boolean-valued preference with the given name. Returns the default-default value (false) if there is no preference with the given name, or if the current value cannot be treated as a boolean.

Specified by:
getBoolean in interface IPreferences
Parameters:
name - the name of the preference
Returns:
the boolean-valued preference

getBoolean

public boolean getBoolean(java.lang.String key,
                          boolean def)
Description copied from interface: IPreferences
Returns the boolean value represented by the string associated with the specified key in this preference node. Valid strings are "true", which represents true, and "false", which represents false. Case is ignored, so, for example, "TRUE" and "False" are also valid. This method is intended for use in conjunction with IPreferences.putBoolean(java.lang.String, boolean).

Returns the specified default if there is no value associated with the key, the backing store is inaccessible, or if the associated value is something other than "true" or "false", ignoring case.

If the implementation supports stored defaults and such a default exists and is accessible, it is used in preference to the specified default, unless the stored default is something other than "true" or "false", ignoring case, in which case the specified default is used.

Specified by:
getBoolean in interface IPreferences
Parameters:
key - key whose associated value is to be returned as a boolean.
def - the value to be returned in the event that this preference node has no value associated with key or the associated value cannot be interpreted as a boolean, or the backing store is inaccessible.
Returns:
the boolean value represented by the string associated with key in this preference node, or def if the associated value does not exist or cannot be interpreted as a boolean.
See Also:
IPreferences.get(String,String), IPreferences.putBoolean(String,boolean)

getByteArray

public byte[] getByteArray(java.lang.String key,
                           byte[] def)
Description copied from interface: IPreferences
Returns the byte array value represented by the string associated with the specified key in this preference node. Valid strings are Base64 encoded binary data, as defined in RFC 2045, Section 6.8, with one minor change: the string must consist solely of characters from the Base64 Alphabet; no newline characters or extraneous characters are permitted. This method is intended for use in conjunction with IPreferences.putByteArray(java.lang.String, byte[]).

Returns the specified default if there is no value associated with the key, the backing store is inaccessible, or if the associated value is not a valid Base64 encoded byte array (as defined above).

If the implementation supports stored defaults and such a default exists and is accessible, it is used in preference to the specified default, unless the stored default is not a valid Base64 encoded byte array (as defined above), in which case the specified default is used.

Specified by:
getByteArray in interface IPreferences
Parameters:
key - key whose associated value is to be returned as a byte array.
def - the value to be returned in the event that this preference node has no value associated with key or the associated value cannot be interpreted as a byte array, or the backing store is inaccessible.
Returns:
the byte array value represented by the string associated with key in this preference node, or def if the associated value does not exist or cannot be interpreted as a byte array.
See Also:
IPreferences.get(String,String), IPreferences.putByteArray(String,byte[])

getDouble

public double getDouble(java.lang.String name)
Description copied from interface: IPreferences
Returns the current value of the double-valued preference with the given name. Returns the default-default value (0.0) if there is no preference with the given name, or if the current value cannot be treated as a double.

Specified by:
getDouble in interface IPreferences
Parameters:
name - the name of the preference
Returns:
the double-valued preference

getDouble

public double getDouble(java.lang.String key,
                        double def)
Description copied from interface: IPreferences
Returns the double value represented by the string associated with the specified key in this preference node. The string is converted to an integer as by Double.parseDouble(String). Returns the specified default if there is no value associated with the key, the backing store is inaccessible, or if Double.parseDouble(String) would throw a NumberFormatException if the associated value were passed. This method is intended for use in conjunction with IPreferences.putDouble(java.lang.String, double).

If the implementation supports stored defaults and such a default exists, is accessible, and could be converted to a double with Double.parseDouble, this double is returned in preference to the specified default.

Specified by:
getDouble in interface IPreferences
Parameters:
key - key whose associated value is to be returned as a double.
def - the value to be returned in the event that this preference node has no value associated with key or the associated value cannot be interpreted as a double, or the backing store is inaccessible.
Returns:
the double value represented by the string associated with key in this preference node, or def if the associated value does not exist or cannot be interpreted as a double.
See Also:
IPreferences.putDouble(String,double), IPreferences.get(String,String)

getFloat

public float getFloat(java.lang.String name)
Description copied from interface: IPreferences
Returns the current value of the float-valued preference with the given name. Returns the default-default value (0.0f) if there is no preference with the given name, or if the current value cannot be treated as a float.

Specified by:
getFloat in interface IPreferences
Parameters:
name - the name of the preference
Returns:
the float-valued preference

getFloat

public float getFloat(java.lang.String key,
                      float def)
Description copied from interface: IPreferences
Returns the float value represented by the string associated with the specified key in this preference node. The string is converted to an integer as by Float.parseFloat(String). Returns the specified default if there is no value associated with the key, the backing store is inaccessible, or if Float.parseFloat(String) would throw a NumberFormatException if the associated value were passed. This method is intended for use in conjunction with IPreferences.putFloat(java.lang.String, float).

If the implementation supports stored defaults and such a default exists, is accessible, and could be converted to a float with Float.parseFloat, this float is returned in preference to the specified default.

Specified by:
getFloat in interface IPreferences
Parameters:
key - key whose associated value is to be returned as a float.
def - the value to be returned in the event that this preference node has no value associated with key or the associated value cannot be interpreted as a float, or the backing store is inaccessible.
Returns:
the float value represented by the string associated with key in this preference node, or def if the associated value does not exist or cannot be interpreted as a float.
See Also:
IPreferences.putFloat(String,float), IPreferences.get(String,String)

getInt

public int getInt(java.lang.String name)
Description copied from interface: IPreferences
Returns the current value of the integer-valued preference with the given name. Returns the default-default value (0) if there is no preference with the given name, or if the current value cannot be treated as an integer.

Specified by:
getInt in interface IPreferences
Parameters:
name - the name of the preference
Returns:
the int-valued preference

getInt

public int getInt(java.lang.String key,
                  int def)
Description copied from interface: IPreferences
Returns the int value represented by the string associated with the specified key in this preference node. The string is converted to an integer as by Integer.parseInt(String). Returns the specified default if there is no value associated with the key, the backing store is inaccessible, or if Integer.parseInt(String) would throw a NumberFormatException if the associated value were passed. This method is intended for use in conjunction with IPreferences.putInt(java.lang.String, int).

If the implementation supports stored defaults and such a default exists, is accessible, and could be converted to an int with Integer.parseInt, this int is returned in preference to the specified default.

Specified by:
getInt in interface IPreferences
Parameters:
key - key whose associated value is to be returned as an int.
def - the value to be returned in the event that this preference node has no value associated with key or the associated value cannot be interpreted as an int, or the backing store is inaccessible.
Returns:
the int value represented by the string associated with key in this preference node, or def if the associated value does not exist or cannot be interpreted as an int.
See Also:
IPreferences.putInt(String,int), IPreferences.get(String,String)

getLong

public long getLong(java.lang.String name)
Description copied from interface: IPreferences
Returns the current value of the long-valued preference with the given name. Returns the default-default value (0L) if there is no preference with the given name, or if the current value cannot be treated as a long.

Specified by:
getLong in interface IPreferences
Parameters:
name - the name of the preference
Returns:
the long-valued preference

getLong

public long getLong(java.lang.String key,
                    long def)
Description copied from interface: IPreferences
Returns the long value represented by the string associated with the specified key in this preference node. The string is converted to a long as by Long.parseLong(String). Returns the specified default if there is no value associated with the key, the backing store is inaccessible, or if Long.parseLong(String) would throw a NumberFormatException if the associated value were passed. This method is intended for use in conjunction with IPreferences.putLong(java.lang.String, long).

If the implementation supports stored defaults and such a default exists, is accessible, and could be converted to a long with Long.parseLong, this long is returned in preference to the specified default.

Specified by:
getLong in interface IPreferences
Parameters:
key - key whose associated value is to be returned as a long.
def - the value to be returned in the event that this preference node has no value associated with key or the associated value cannot be interpreted as a long, or the backing store is inaccessible.
Returns:
the long value represented by the string associated with key in this preference node, or def if the associated value does not exist or cannot be interpreted as a long.
See Also:
IPreferences.putLong(String,long), IPreferences.get(String,String)

keys

public java.lang.String[] keys()
Description copied from interface: IPreferences
Returns all of the keys that have an associated value in this preference node. (The returned array will be of size zero if this node has no preferences.)

If the implementation supports stored defaults and there are any such defaults at this node that have not been overridden, by explicit preferences, the defaults are returned in the array in addition to any explicit preferences.

Specified by:
keys in interface IPreferences
Returns:
an array of the keys that have an associated value in this preference node.

name

public java.lang.String name()
Description copied from interface: IPreferences
Returns this preference node's name, relative to its parent.

Specified by:
name in interface IPreferences
Returns:
this preference node's name, relative to its parent.

node

public IPreferences node(java.lang.String pathName)
Description copied from interface: IPreferences
Returns the named preference node in the same tree as this node, creating it and any of its ancestors if they do not already exist. Accepts a relative or absolute path name. Relative path names (which do not begin with the slash character ('/')) are interpreted relative to this preference node.

If the returned node did not exist prior to this call, this node and any ancestors that were created by this call are not guaranteed to become permanent until the flush method is called on the returned node (or one of its ancestors or descendants).

Specified by:
node in interface IPreferences
Parameters:
pathName - the path name of the preference node to return.
Returns:
the specified preference node.
See Also:
IPreferences.flush()

nodeExists

public boolean nodeExists(java.lang.String pathName)
                   throws java.util.prefs.BackingStoreException
Description copied from interface: IPreferences
Returns true if the named preference node exists in the same tree as this node. Relative path names (which do not begin with the slash character ('/')) are interpreted relative to this preference node.

If this node (or an ancestor) has already been removed with the IPreferences.removeNode() method, it is legal to invoke this method, but only with the path name ""; the invocation will return false. Thus, the idiom p.nodeExists("") may be used to test whether p has been removed.

Specified by:
nodeExists in interface IPreferences
Parameters:
pathName - the path name of the node whose existence is to be checked.
Returns:
true if the specified node exists.
Throws:
java.util.prefs.BackingStoreException - if this operation cannot be completed due to a failure in the backing store, or inability to communicate with it.

parent

public IPreferences parent()
Description copied from interface: IPreferences
Returns the parent of this preference node, or null if this is the root.

Specified by:
parent in interface IPreferences
Returns:
the parent of this preference node.

properties

public java.util.Map<java.lang.String,java.lang.String> properties()
Description copied from interface: IPreferences
A map of all property mappings in this IPreferences node.

Specified by:
properties in interface IPreferences
Returns:
A map of all property mappings in this IPreferences node.

put

public void put(java.lang.String name,
                boolean value)
Description copied from interface: IPreferences
Sets the current value of the boolean-valued preference with the given name.

Specified by:
put in interface IPreferences
Parameters:
name - the name of the preference
value - the new current value of the preference

put

public void put(java.lang.String key,
                byte[] value)
Description copied from interface: IPreferences
Associates a string representing the specified byte array with the specified key in this preference node. The associated string is the Base64 encoding of the byte array, as defined in RFC 2045, Section 6.8, with one minor change: the string will consist solely of characters from the Base64 Alphabet; it will not contain any newline characters. Note that the maximum length of the byte array is limited to three quarters of MAX_VALUE_LENGTH so that the length of the Base64 encoded String does not exceed MAX_VALUE_LENGTH. This method is intended for use in conjunction with IPreferences.getByteArray(java.lang.String, byte[]).

Specified by:
put in interface IPreferences
Parameters:
key - key with which the string form of value is to be associated.
value - value whose string form is to be associated with key.
See Also:
IPreferences.getByteArray(String,byte[]), IPreferences.get(String,String)

put

public void put(java.lang.String name,
                double value)
Description copied from interface: IPreferences
Sets the current value of the double-valued preference with the given name.

Specified by:
put in interface IPreferences
Parameters:
name - the name of the preference
value - the new current value of the preference

put

public void put(java.lang.String name,
                float value)
Description copied from interface: IPreferences
Sets the current value of the float-valued preference with the given name.

Specified by:
put in interface IPreferences
Parameters:
name - the name of the preference
value - the new current value of the preference

put

public void put(java.lang.String name,
                int value)
Description copied from interface: IPreferences
Sets the current value of the integer-valued preference with the given name.

Specified by:
put in interface IPreferences
Parameters:
name - the name of the preference
value - the new current value of the preference

put

public void put(java.lang.String name,
                long value)
Description copied from interface: IPreferences
Sets the current value of the long-valued preference with the given name.

Specified by:
put in interface IPreferences
Parameters:
name - the name of the preference
value - the new current value of the preference

put

public void put(java.lang.String name,
                java.lang.String value)
Description copied from interface: IPreferences
Sets the current value of the string-valued preference with the given name.

Specified by:
put in interface IPreferences
Parameters:
name - the name of the preference
value - the new current value of the preference

putBoolean

public void putBoolean(java.lang.String key,
                       boolean value)
Description copied from interface: IPreferences
Set the current value. This is for drop in compatibility to Java platform preferences.

Specified by:
putBoolean in interface IPreferences

putByteArray

public void putByteArray(java.lang.String key,
                         byte[] value)
Description copied from interface: IPreferences
Set the current value. This is for drop in compatibility to Java platform preferences.

Specified by:
putByteArray in interface IPreferences

putDouble

public void putDouble(java.lang.String key,
                      double value)
Description copied from interface: IPreferences
Set the current value. This is for drop in compatibility to Java platform preferences.

Specified by:
putDouble in interface IPreferences

putFloat

public void putFloat(java.lang.String key,
                     float value)
Description copied from interface: IPreferences
Set the current value. This is for drop in compatibility to Java platform preferences.

Specified by:
putFloat in interface IPreferences

putInt

public void putInt(java.lang.String key,
                   int value)
Description copied from interface: IPreferences
Set the current value. This is for drop in compatibility to Java platform preferences.

Specified by:
putInt in interface IPreferences

putLong

public void putLong(java.lang.String key,
                    long value)
Description copied from interface: IPreferences
Set the current value. This is for drop in compatibility to Java platform preferences.

Specified by:
putLong in interface IPreferences

remove

public void remove(java.lang.String key)
Description copied from interface: IPreferences
Removes the value associated with the specified key in this preference node, if any.

If this implementation supports stored defaults, and there is such a default for the specified preference, the stored default will be "exposed" by this call, in the sense that it will be returned by a succeeding call to get.

Specified by:
remove in interface IPreferences
Parameters:
key - key whose mapping is to be removed from the preference node.

removeNode

public void removeNode()
                throws java.util.prefs.BackingStoreException
Description copied from interface: IPreferences
Removes this preference node and all of its descendants, invalidating any preferences contained in the removed nodes. Once a node has been removed, attempting any method other than IPreferences.name(), IPreferences.absolutePath() , IPreferences.flush() or nodeExists("") on the corresponding Preferences instance will fail with an IllegalStateException. (The methods defined on Object can still be invoked on a node after it has been removed; they will not throw IllegalStateException.)

The removal is not guaranteed to be persistent until the flush method is called on this node (or an ancestor).

If this implementation supports stored defaults, removing a node exposes any stored defaults at or below this node. Thus, a subsequent call to nodeExists on this node's path name may return true, and a subsequent call to node on this path name may may return a (different) Preferences instance representing a non-empty collection of preferences and/or children.

Specified by:
removeNode in interface IPreferences
Throws:
java.util.prefs.BackingStoreException - if this operation cannot be completed due to a failure in the backing store, or inability to communicate with it.
See Also:
IPreferences.flush()

restrict

public IPreferences restrict(java.lang.String scopeName)
Description copied from interface: IPreferences
Create a new IPreferences object whose scopes include all scopes from the receiver before and including "scopeName".

Specified by:
restrict in interface IPreferences
Returns:
a new IPreferences object whose scopes include all scopes from the receiver before and including "scopeName".

sync

public void sync()
          throws java.util.prefs.BackingStoreException
Description copied from interface: IPreferences
Ensures that future reads from this preference node and its descendants reflect any changes that were committed to the persistent store (from any VM) prior to the sync invocation. As a side-effect, forces any changes in the contents of this preference node and its descendants to the persistent store, as if the flush method had been invoked on this node.

Specified by:
sync in interface IPreferences
Throws:
java.util.prefs.BackingStoreException - if this operation cannot be completed due to a failure in the backing store, or inability to communicate with it.
See Also:
IPreferences.flush()