java.lang.Object
- java.util.prefs.Preferences

Direct Known Subclasses:

AbstractPreferences
```
public abstract class Preferences
extends Object
```
An instance of the class Preferences represents one node in a preference tree, which provides a mechanism to store and access configuration data in a hierarchical way. Two hierarchy trees are maintained, one for system preferences shared by all users and the other for user preferences specific to the user. Preferences hierarchy trees and data are stored in an implementation-dependent back-end.
Every node has one name and one unique absolute path following the same notational conventions as directories in a file system. The root node's name is "", and other node name strings cannot contain the slash character and cannot be empty. The root node's absolute path is "/", and all other nodes' absolute paths are constructed in the standard way: <parent's absolute path> + "/" + <node's name>. Since the set of nodes forms a tree with the root node at its base, all absolute paths start with the slash character. Every node has one relative path to each of its ancestors. The relative path doesn't start with slash: it equals the node's absolute path with leading substring removed corresponding to the ancestor's absolute path and a slash.
Modification to preferences data may be asynchronous, which means that preference update method calls may return immediately instead of blocking. The flush() and sync() methods force the back-end to synchronously perform all pending updates, but the implementation is permitted to perform the modifications on the underlying back-end data at any time between the moment the request is made and the moment the flush() or sync() method returns. Please note that if the JVM exits normally, the implementation must assure all modifications are persisted implicitly.
When invoking a method that retrieves preferences, the user must provide a default value. The default value is returned when the preferences cannot be found or the back-end is unavailable. Some other methods will throw BackingStoreException when the back-end is unavailable.

Preferences can be exported to and imported from an XML files. These documents must have an XML DOCTYPE declaration:
```
 <!DOCTYPE preferences SYSTEM "http://java.sun.com/dtd/preferences.dtd">
 
```
This system URI is not really accessed by network, it is only a identification string. Visit the DTD location to see the actual format permitted.
There must be a concrete PreferencesFactory type for every concrete Preferences type developed. Every J2SE implementation must provide a default implementation for every supported platform, and must also provide a means of replacing the default implementation. This implementation uses the system property java.util.prefs.PreferencesFactory to determine which preferences implementation to use.
The methods of this class are thread-safe. If multiple JVMs are using the same back-end concurrently, the back-end won't be corrupted, but no other behavior guarantees are made.
Since:

1.4

See Also:

PreferencesFactory

Field Summary

Fields
Modifier and Type	Field	Description
`static int`	`MAX_KEY_LENGTH`	Maximum size in characters allowed for a preferences key.
`static int`	`MAX_NAME_LENGTH`	Maximum size in characters allowed for a preferences name.
`static int`	`MAX_VALUE_LENGTH`	Maximum size in characters allowed for a preferences value.

Constructor Summary

Constructors
Modifier Constructor Description

protected Preferences()
Default constructor, for use by subclasses only.

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method	Description
`abstract String`	`absolutePath()`	Gets the absolute path string of this preference node.
`abstract void`	`addNodeChangeListener(NodeChangeListener ncl)`	Registers a `NodeChangeListener` instance for this node, which will handle `NodeChangeEvent`s.
`abstract void`	`addPreferenceChangeListener(PreferenceChangeListener pcl)`	Registers a `PreferenceChangeListener` instance for this node, which will handle `PreferenceChangeEvent`s.
`abstract String[]`	`childrenNames()`	Returns the names of all children of this node or an empty array if this node has no children.
`abstract void`	`clear()`	Removes all preferences of this node.
`abstract void`	`exportNode(OutputStream ostream)`	Exports all of the preferences of this node to a XML document using the given output stream.
`abstract void`	`exportSubtree(OutputStream ostream)`	Exports all of the preferences of this node and all its descendants to a XML document using the given output stream.
`abstract void`	`flush()`	Forces all pending updates to this node and its descendants to be persisted in the backing store.
`abstract String`	`get(String key, String deflt)`	Gets the `String` value mapped to the given key or its default value if no value is mapped or no backing store is available.
`abstract boolean`	`getBoolean(String key, boolean deflt)`	Gets the `boolean` value mapped to the given key or its default value if no value is mapped, if the backing store is unavailable, or if the value is invalid.
`abstract byte[]`	`getByteArray(String key, byte[] deflt)`	Gets the `byte` array value mapped to the given key or its default value if no value is mapped, if the backing store is unavailable, or if the value is an invalid string.
`abstract double`	`getDouble(String key, double deflt)`	Gets the `double` value mapped to the given key or its default value if no value is mapped, if the backing store is unavailable, or if the value is an invalid string.
`abstract float`	`getFloat(String key, float deflt)`	Gets the `float` value mapped to the given key or its default value if no value is mapped, if the backing store is unavailable, or if the value is an invalid string.
`abstract int`	`getInt(String key, int deflt)`	Gets the `int` value mapped to the given key or its default value if no value is mapped, if the backing store is unavailable, or if the value is an invalid string.
`abstract long`	`getLong(String key, long deflt)`	Gets the `long` value mapped to the given key or its default value if no value is mapped, if the backing store is unavailable, or if the value is an invalid string.
`static void`	`importPreferences(InputStream istream)`	Imports all the preferences from an XML document using the given input stream.
`abstract boolean`	`isUserNode()`	Returns whether this is a user preference node.
`abstract String[]`	`keys()`	Returns all preference keys stored in this node or an empty array if no key was found.
`abstract String`	`name()`	Returns the name of this node.
`abstract Preferences`	`node(String path)`	Returns the preference node with the given path name.
`abstract boolean`	`nodeExists(String path)`	Returns whether the preference node with the given path name exists.
`abstract Preferences`	`parent()`	Returns the parent preference node of this node or `null` if this node is the root node.
`abstract void`	`put(String key, String value)`	Adds a new preference to this node using the given key and value or updates the value if a preference with the given key already exists.
`abstract void`	`putBoolean(String key, boolean value)`	Adds a new preference with a `boolean` value to this node using the given key and value or updates the value if a preference with the given key already exists.
`abstract void`	`putByteArray(String key, byte[] value)`	Adds a new preference to this node using the given key and the string form of the given value or updates the value if a preference with the given key already exists.
`abstract void`	`putDouble(String key, double value)`	Adds a new preference to this node using the given key and `double` value or updates the value if a preference with the given key already exists.
`abstract void`	`putFloat(String key, float value)`	Adds a new preference to this node using the given key and `float` value or updates the value if a preference with the given key already exists.
`abstract void`	`putInt(String key, int value)`	Adds a new preference to this node using the given key and `int` value or updates the value if a preference with the given key already exists.
`abstract void`	`putLong(String key, long value)`	Adds a new preference to this node using the given key and `long` value or updates the value if a preference with the given key already exists.
`abstract void`	`remove(String key)`	Removes the preference mapped to the given key from this node.
`abstract void`	`removeNode()`	Removes this preference node with all its descendants.
`abstract void`	`removeNodeChangeListener(NodeChangeListener ncl)`	Removes the given `NodeChangeListener` instance from this node.
`abstract void`	`removePreferenceChangeListener(PreferenceChangeListener pcl)`	Removes the given `PreferenceChangeListener` instance from this node.
`static PreferencesFactory`	`setPreferencesFactory(PreferencesFactory pf)`
`abstract void`	`sync()`	Synchronizes the data of this preference node and its descendants with the back-end preference store.
`static Preferences`	`systemNodeForPackage(Class<?> c)`	Legacy code; do not use. On Android, the Preference nodes corresponding to the "system" and "user" preferences are stored in sections of the file system that are inaccessible to apps.
`static Preferences`	`systemRoot()`	Legacy code; do not use. On Android, the Preference nodes corresponding to the "system" and "user" preferences are stored in sections of the file system that are inaccessible to apps.
`abstract String`	`toString()`	Returns a string representation of this node.
`static Preferences`	`userNodeForPackage(Class<?> c)`	Legacy code; do not use. On Android, the Preference nodes corresponding to the "system" and "user" preferences are stored in sections of the file system that are inaccessible to apps.
`static Preferences`	`userRoot()`	Legacy code; do not use. On Android, the Preference nodes corresponding to the "system" and "user" preferences are stored in sections of the file system that are inaccessible to apps.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - MAX_KEY_LENGTH
```
public static final int MAX_KEY_LENGTH
```
    Maximum size in characters allowed for a preferences key.
    
    See Also:
    
    Constant Field Values
  - MAX_NAME_LENGTH
```
public static final int MAX_NAME_LENGTH
```
    Maximum size in characters allowed for a preferences name.
    
    See Also:
    
    Constant Field Values
  - MAX_VALUE_LENGTH
```
public static final int MAX_VALUE_LENGTH
```
    Maximum size in characters allowed for a preferences value.
    
    See Also:
    
    Constant Field Values
- Constructor Detail
  - Preferences
```
protected Preferences()
```
    Default constructor, for use by subclasses only.
- Method Detail
  - setPreferencesFactory
```
public static PreferencesFactory setPreferencesFactory(PreferencesFactory pf)
```
  - absolutePath
```
public abstract String absolutePath()
```
    Gets the absolute path string of this preference node.
    
    Returns:
    
    the preference node's absolute path string.
  - childrenNames
```
public abstract String[] childrenNames()
                                throws BackingStoreException
```
    Returns the names of all children of this node or an empty array if this node has no children.
    
    Returns:
    
    the names of all children of this node.
    
    Throws:
    
    BackingStoreException - if backing store is unavailable or causes an operation failure.
    
    IllegalStateException - if this node has been removed.
  - clear
```
public abstract void clear()
                    throws BackingStoreException
```
    Removes all preferences of this node.
    
    Throws:
    
    BackingStoreException - if backing store is unavailable or causes an operation failure.
    
    IllegalStateException - if this node has been removed.
  - exportNode
```
public abstract void exportNode(OutputStream ostream)
                         throws IOException,
                                BackingStoreException
```
    Exports all of the preferences of this node to a XML document using the given output stream.
    This XML document uses the UTF-8 encoding and is written according to the DTD in its DOCTYPE declaration, which is the following:
    <!DOCTYPE preferences SYSTEM "http://java.sun.com/dtd/preferences.dtd">
    Please note that (unlike the methods of this class that don't concern serialization), this call is not thread-safe.
    Parameters:
    
    ostream - the output stream to write the XML-formatted data to.
    
    Throws:
    
    IOException - if an error occurs while exporting.
    
    BackingStoreException - if the backing store is unavailable or causes an operation failure.
    
    IllegalStateException - if this node has been removed.
  - exportSubtree
```
public abstract void exportSubtree(OutputStream ostream)
                            throws IOException,
                                   BackingStoreException
```
    Exports all of the preferences of this node and all its descendants to a XML document using the given output stream.
    This XML document uses the UTF-8 encoding and is written according to the DTD in its DOCTYPE declaration, which is the following:
    <!DOCTYPE preferences SYSTEM "http://java.sun.com/dtd/preferences.dtd">
    Please note that (unlike the methods of this class that don't concern serialization), this call is not thread-safe.
    Parameters:
    
    ostream - the output stream to write the XML-formatted data to.
    
    Throws:
    
    IOException - if an error occurs while exporting.
    
    BackingStoreException - if the backing store is unavailable or causes an operation failure.
    
    IllegalStateException - if this node has been removed.
  - flush
```
public abstract void flush()
                    throws BackingStoreException
```
    Forces all pending updates to this node and its descendants to be persisted in the backing store.
    If this node has been removed, the invocation of this method only flushes this node, not its descendants.
    
    Throws:
    
    BackingStoreException - if the backing store is unavailable or causes an operation failure.
  - get
```
public abstract String get(String key,
                           String deflt)
```
    Gets the String value mapped to the given key or its default value if no value is mapped or no backing store is available.
    Some implementations may store default values in backing stores. In this case, if there is no value mapped to the given key, the stored default value is returned.
    
    Parameters:
    
    key - the preference key.
    
    deflt - the default value, which will be returned if no value is mapped to the given key or no backing store is available.
    
    Returns:
    
    the preference value mapped to the given key.
    
    Throws:
    
    IllegalStateException - if this node has been removed.
    
    NullPointerException - if the parameter key is null.
  - getBoolean
```
public abstract boolean getBoolean(String key,
                                   boolean deflt)
```
    Gets the boolean value mapped to the given key or its default value if no value is mapped, if the backing store is unavailable, or if the value is invalid.
    The only valid values are the String "true", which represents true and "false", which represents false, ignoring case.
    
    Some implementations may store default values in backing stores. In this case, if there is no value mapped to the given key, the stored default value is returned.
    
    Parameters:
    
    key - the preference key.
    
    deflt - the default value, which will be returned if no value is mapped to the given key, if the backing store is unavailable, or if the value is invalid.
    
    Returns:
    
    the boolean value mapped to the given key.
    
    Throws:
    
    IllegalStateException - if this node has been removed.
    
    NullPointerException - if the parameter key is null.
  - getByteArray
```
public abstract byte[] getByteArray(String key,
                                    byte[] deflt)
```
    Gets the byte array value mapped to the given key or its default value if no value is mapped, if the backing store is unavailable, or if the value is an invalid string.
    To be valid, the value string must be Base64-encoded binary data. The Base64 encoding is as defined in RFC 2045, section 6.8.
    
    Some implementations may store default values in backing stores. In this case, if there is no value mapped to the given key, the stored default value is returned.
    
    Parameters:
    
    key - the preference key.
    
    deflt - the default value, which will be returned if no value is mapped to the given key, if the backing store is unavailable, or if the value is invalid.
    
    Returns:
    
    the byte array value mapped to the given key.
    
    Throws:
    
    IllegalStateException - if this node has been removed.
    
    NullPointerException - if the parameter key is null.
  - getDouble
```
public abstract double getDouble(String key,
                                 double deflt)
```
    Gets the double value mapped to the given key or its default value if no value is mapped, if the backing store is unavailable, or if the value is an invalid string.
    To be valid, the value string must be a string that can be converted to a double by Double.parseDouble(String).
    Some implementations may store default values in backing stores. In this case, if there is no value mapped to the given key, the stored default value is returned.
    
    Parameters:
    
    key - the preference key.
    
    deflt - the default value, which will be returned if no value is mapped to the given key, if the backing store is unavailable, or if the value is invalid.
    
    Returns:
    
    the double value mapped to the given key.
    
    Throws:
    
    IllegalStateException - if this node has been removed.
    
    NullPointerException - if the parameter key is null.
  - getFloat
```
public abstract float getFloat(String key,
                               float deflt)
```
    Gets the float value mapped to the given key or its default value if no value is mapped, if the backing store is unavailable, or if the value is an invalid string.
    To be valid, the value string must be a string that can be converted to a float by Float.parseFloat(String).
    
    Some implementations may store default values in backing stores. In this case, if there is no value mapped to the given key, the stored default value is returned.
    
    Parameters:
    
    key - the preference key.
    
    deflt - the default value, which will be returned if no value is mapped to the given key, if the backing store is unavailable, or if the value is invalid.
    
    Returns:
    
    the float value mapped to the given key.
    
    Throws:
    
    IllegalStateException - if this node has been removed.
    
    NullPointerException - if the parameter key is null.
  - getInt
```
public abstract int getInt(String key,
                           int deflt)
```
    Gets the int value mapped to the given key or its default value if no value is mapped, if the backing store is unavailable, or if the value is an invalid string.
    To be valid, the value string must be a string that can be converted to an int by Integer.parseInt(String).
    
    Some implementations may store default values in backing stores. In this case, if there is no value mapped to the given key, the stored default value is returned.
    
    Parameters:
    
    key - the preference key.
    
    deflt - the default value, which will be returned if no value is mapped to the given key, if the backing store is unavailable, or if the value is invalid.
    
    Returns:
    
    the integer value mapped to the given key.
    
    Throws:
    
    IllegalStateException - if this node has been removed.
    
    NullPointerException - if the parameter key is null.
  - getLong
```
public abstract long getLong(String key,
                             long deflt)
```
    Gets the long value mapped to the given key or its default value if no value is mapped, if the backing store is unavailable, or if the value is an invalid string.
    To be valid, the value string must be a string that can be converted to a long by Long.parseLong(String).
    
    Some implementations may store default values in backing stores. In this case, if there is no value mapped to the given key, the stored default value is returned.
    
    Parameters:
    
    key - the preference key.
    
    deflt - the default value, which will be returned if no value is mapped to the given key, if the backing store is unavailable, or if the value is invalid.
    
    Returns:
    
    the long value mapped to the given key.
    
    Throws:
    
    IllegalStateException - if this node has been removed.
    
    NullPointerException - if the parameter key is null.
  - importPreferences
```
public static void importPreferences(InputStream istream)
                              throws InvalidPreferencesFormatException,
                                     IOException
```
    Imports all the preferences from an XML document using the given input stream.
    This XML document uses the UTF-8 encoding and must be written according to the DTD in its DOCTYPE declaration, which must be the following:
    <!DOCTYPE preferences SYSTEM "http://java.sun.com/dtd/preferences.dtd">
    Please note that (unlike the methods of this class that don't concern serialization), this call is not thread-safe.
    Parameters:
    
    istream - the input stream to read the data from.
    
    Throws:
    
    InvalidPreferencesFormatException - if the data read from the given input stream is not from a valid XML document.
    
    IOException - if an error occurs while importing.
  - isUserNode
```
public abstract boolean isUserNode()
```
    Returns whether this is a user preference node.
    
    Returns:
    
    true, if this is a user preference node, false if this is a system preference node.
  - keys
```
public abstract String[] keys()
                       throws BackingStoreException
```
    Returns all preference keys stored in this node or an empty array if no key was found.
    
    Returns:
    
    the list of all preference keys of this node.
    
    Throws:
    
    BackingStoreException - if the backing store is unavailable or causes an operation failure.
    
    IllegalStateException - if this node has been removed.
  - name
```
public abstract String name()
```
    Returns the name of this node.
    
    Returns:
    
    the name of this node.
  - node
```
public abstract Preferences node(String path)
```
    Returns the preference node with the given path name. The path name can be relative or absolute. The requested node and its ancestors will be created if they do not exist.
    The path is treated as relative to this node if it doesn't start with a slash, otherwise it will be treated as an absolute path.
    
    Parameters:
    
    path - the path name of the requested preference node.
    
    Returns:
    
    the requested preference node.
    
    Throws:
    
    IllegalStateException - if this node has been removed.
    
    IllegalArgumentException - if the path name is invalid.
    
    NullPointerException - if the given path is null.
  - nodeExists
```
public abstract boolean nodeExists(String path)
                            throws BackingStoreException
```
    Returns whether the preference node with the given path name exists. The path is treated as relative to this node if it doesn't start with a slash, otherwise it is treated as an absolute path.
    Please note that if this node has been removed, an invocation of this node will throw an IllegalStateException unless the given path is an empty string, which will return false.
    
    Parameters:
    
    path - the path name of the preference node to query.
    
    Returns:
    
    true, if the queried preference node exists, false otherwise.
    
    Throws:
    
    IllegalStateException - if this node has been removed and the path is not an empty string.
    
    IllegalArgumentException - if the path name is invalid.
    
    NullPointerException - if the given path is null.
    
    BackingStoreException - if the backing store is unavailable or causes an operation failure.
  - parent
```
public abstract Preferences parent()
```
    Returns the parent preference node of this node or null if this node is the root node.
    
    Returns:
    
    the parent preference node of this node.
    
    Throws:
    
    IllegalStateException - if this node has been removed.
  - put
```
public abstract void put(String key,
                         String value)
```
    Adds a new preference to this node using the given key and value or updates the value if a preference with the given key already exists.
    
    Parameters:
    
    key - the preference key to be added or updated.
    
    value - the preference value for the given key.
    
    Throws:
    
    NullPointerException - if the given key or value is null.
    
    IllegalArgumentException - if the given key's length is bigger than MAX_KEY_LENGTH or the value's length is bigger than MAX_VALUE_LENGTH.
    
    IllegalStateException - if this node has been removed.
  - putBoolean
```
public abstract void putBoolean(String key,
                                boolean value)
```
    Adds a new preference with a boolean value to this node using the given key and value or updates the value if a preference with the given key already exists.
    
    Parameters:
    
    key - the preference key to be added or updated.
    
    value - the preference boolean value for the given key.
    
    Throws:
    
    NullPointerException - if the given key is null.
    
    IllegalArgumentException - if the given key's length is bigger than MAX_KEY_LENGTH.
    
    IllegalStateException - if this node has been removed.
  - putByteArray
```
public abstract void putByteArray(String key,
                                  byte[] value)
```
    Adds a new preference to this node using the given key and the string form of the given value or updates the value if a preference with the given key already exists.
    The string form of the value is the Base64-encoded binary data of the given byte array. The Base64 encoding is as defined in RFC 2045, section 6.8.
    
    Parameters:
    
    key - the preference key to be added or updated.
    
    value - the preference value for the given key.
    
    Throws:
    
    NullPointerException - if the given key or value is null.
    
    IllegalArgumentException - if the given key's length is bigger than MAX_KEY_LENGTH or value's length is bigger than three quarters of MAX_KEY_LENGTH.
    
    IllegalStateException - if this node has been removed.
  - putDouble
```
public abstract void putDouble(String key,
                               double value)
```
    Adds a new preference to this node using the given key and double value or updates the value if a preference with the given key already exists.
    The value is stored in its string form, which is the result of invoking Double.toString(double).
    
    Parameters:
    
    key - the preference key to be added or updated.
    
    value - the preference value for the given key.
    
    Throws:
    
    NullPointerException - if the given key is null.
    
    IllegalArgumentException - if the given key's length is bigger than MAX_KEY_LENGTH.
    
    IllegalStateException - if this node has been removed.
  - putFloat
```
public abstract void putFloat(String key,
                              float value)
```
    Adds a new preference to this node using the given key and float value or updates the value if a preference with the given key already exists.
    The value is stored in its string form, which is the result of invoking Float.toString(float).
    
    Parameters:
    
    key - the preference key to be added or updated.
    
    value - the preference value for the given key.
    
    Throws:
    
    NullPointerException - if the given key is null.
    
    IllegalArgumentException - if the given key's length is bigger than MAX_KEY_LENGTH.
    
    IllegalStateException - if this node has been removed.
  - putInt
```
public abstract void putInt(String key,
                            int value)
```
    Adds a new preference to this node using the given key and int value or updates the value if a preference with the given key already exists.
    The value is stored in its string form, which is the result of invoking Integer.toString(int).
    
    Parameters:
    
    key - the preference key to be added or updated.
    
    value - the preference value for the given key.
    
    Throws:
    
    NullPointerException - if the given key is null.
    
    IllegalArgumentException - if the given key's length is bigger than MAX_KEY_LENGTH.
    
    IllegalStateException - if this node has been removed.
  - putLong
```
public abstract void putLong(String key,
                             long value)
```
    Adds a new preference to this node using the given key and long value or updates the value if a preference with the given key already exists.
    The value is stored in its string form, which is the result of invoking Long.toString(long).
    
    Parameters:
    
    key - the preference key to be added or updated.
    
    value - the preference value for the given key.
    
    Throws:
    
    NullPointerException - if the given key is null.
    
    IllegalArgumentException - if the given key's length is bigger than MAX_KEY_LENGTH.
    
    IllegalStateException - if this node has been removed.
  - remove
```
public abstract void remove(String key)
```
    Removes the preference mapped to the given key from this node.
    
    Parameters:
    
    key - the key of the preference to be removed.
    
    Throws:
    
    NullPointerException - if the given key is null.
    
    IllegalStateException - if this node has been removed.
  - removeNode
```
public abstract void removeNode()
                         throws BackingStoreException
```
    Removes this preference node with all its descendants. The removal won't necessarily be persisted until the method flush() is invoked.
    
    Throws:
    
    BackingStoreException - if the backing store is unavailable or causes an operation failure.
    
    IllegalStateException - if this node has been removed.
    
    UnsupportedOperationException - if this is a root node.
  - addNodeChangeListener
```
public abstract void addNodeChangeListener(NodeChangeListener ncl)
```
    Registers a NodeChangeListener instance for this node, which will handle NodeChangeEvents. NodeChangeEvents will be fired when a child node has been added to or removed from this node.
    
    Parameters:
    
    ncl - the listener to be registered.
    
    Throws:
    
    NullPointerException - if the given listener is null.
    
    IllegalStateException - if this node has been removed.
  - addPreferenceChangeListener
```
public abstract void addPreferenceChangeListener(PreferenceChangeListener pcl)
```
    Registers a PreferenceChangeListener instance for this node, which will handle PreferenceChangeEvents. PreferenceChangeEvents will be fired when a preference has been added to, removed from, or updated for this node.
    
    Parameters:
    
    pcl - the listener to be registered.
    
    Throws:
    
    NullPointerException - if the given listener is null.
    
    IllegalStateException - if this node has been removed.
  - removeNodeChangeListener
```
public abstract void removeNodeChangeListener(NodeChangeListener ncl)
```
    Removes the given NodeChangeListener instance from this node.
    
    Parameters:
    
    ncl - the listener to be removed.
    
    Throws:
    
    IllegalArgumentException - if the given listener is null.
    
    IllegalStateException - if this node has been removed.
  - removePreferenceChangeListener
```
public abstract void removePreferenceChangeListener(PreferenceChangeListener pcl)
```
    Removes the given PreferenceChangeListener instance from this node.
    
    Parameters:
    
    pcl - the listener to be removed.
    
    Throws:
    
    IllegalArgumentException - if the given listener is null.
    
    IllegalStateException - if this node has been removed.
  - sync
```
public abstract void sync()
                   throws BackingStoreException
```
    Synchronizes the data of this preference node and its descendants with the back-end preference store. Any changes found in the back-end data should be reflected in this node and its descendants, and at the same time any local changes to this node and descendants should be persisted.
    
    Throws:
    
    BackingStoreException - if the backing store is unavailable or causes an operation failure.
    
    IllegalStateException - if this node has been removed.
  - systemNodeForPackage
```
public static Preferences systemNodeForPackage(Class<?> c)
```
    Legacy code; do not use. On Android, the Preference nodes corresponding to the "system" and "user" preferences are stored in sections of the file system that are inaccessible to apps. Further, allowing apps to set "system wide" preferences is contrary to android's security model. Returns the system preference node for the package of the given class. The absolute path of the returned node is one slash followed by the given class's full package name, replacing each period character ('.') with a slash. For example, the absolute path of the preference associated with the class Object would be "/java/lang". As a special case, the unnamed package is associated with a preference node "/<unnamed>". This method will create the node and its ancestors as needed. Any nodes created by this method won't necessarily be persisted until the method flush() is invoked.
    
    Parameters:
    
    c - the given class.
    
    Returns:
    
    the system preference node for the package of the given class.
    
    Throws:
    
    NullPointerException - if the given class is null.
  - systemRoot
```
public static Preferences systemRoot()
```
    Legacy code; do not use. On Android, the Preference nodes corresponding to the "system" and "user" preferences are stored in sections of the file system that are inaccessible to apps. Further, allowing apps to set "system wide" preferences is contrary to android's security model. Returns the root node of the system preference hierarchy.
    
    Returns:
    
    the system preference hierarchy root node.
  - userNodeForPackage
```
public static Preferences userNodeForPackage(Class<?> c)
```
    Legacy code; do not use. On Android, the Preference nodes corresponding to the "system" and "user" preferences are stored in sections of the file system that are inaccessible to apps. Further, allowing apps to set "system wide" preferences is contrary to android's security model.
    Returns the user preference node for the package of the given class. The absolute path of the returned node is one slash followed by the given class's full package name, replacing each period character ('.') with a slash. For example, the absolute path of the preference associated with the class Object would be "/java/lang". As a special case, the unnamed package is associated with a preference node "/<unnamed>". This method will create the node and its ancestors as needed. Any nodes created by this method won't necessarily be persisted until the method flush() is invoked.
    
    Returns:
    
    the user preference node for the package of the given class.
    
    Throws:
    
    NullPointerException - if the given class is null.
  - userRoot
```
public static Preferences userRoot()
```
    Legacy code; do not use. On Android, the Preference nodes corresponding to the "system" and "user" preferences are stored in sections of the file system that are inaccessible to apps. Further, allowing apps to set "system wide" preferences is contrary to android's security model. Returns the root node of the user preference hierarchy.
    
    Returns:
    
    the user preference hierarchy root node.
  - toString
```
public abstract String toString()
```
    Returns a string representation of this node. The format is "User/System Preference Node: " followed by this node's absolute path.
    
    Overrides:
    
    toString in class Object
    
    Returns:
    
    the string representation of this node.

Class Preferences

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

MAX_KEY_LENGTH

MAX_NAME_LENGTH

MAX_VALUE_LENGTH

Constructor Detail

Preferences

Method Detail

setPreferencesFactory

absolutePath

childrenNames

clear

exportNode

exportSubtree

flush

get

getBoolean

getByteArray

getDouble

getFloat

getInt

getLong

importPreferences

isUserNode

keys

name

node

nodeExists

parent

put

putBoolean

putByteArray

putDouble

putFloat

putInt

putLong

remove

removeNode

addNodeChangeListener

addPreferenceChangeListener

removeNodeChangeListener

removePreferenceChangeListener

sync

systemNodeForPackage

systemRoot

userNodeForPackage

userRoot

toString