org.apache.commons.configuration
Class ConfigurationKey

java.lang.Object
  org.apache.commons.configuration.ConfigurationKey

All Implemented Interfaces:

Serializable

public class ConfigurationKey

extends Object

implements Serializable

A simple class that supports creation of and iteration on complex configuration keys.

For key creation the class works similar to a StringBuffer: There are several appendXXXX() methods with which single parts of a key can be constructed. All these methods return a reference to the actual object so they can be written in a chain. When using this methods the exact syntax for keys need not be known.

This class also defines a specialized iterator for configuration keys. With such an iterator a key can be tokenized into its single parts. For each part it can be checked whether it has an associated index.

Version:

$Id: ConfigurationKey.java,v 1.5 2004/08/14 11:23:14 epugh Exp $

Author:

Oliver Heger

See Also:

Serialized Form

Nested Class Summary

class

ConfigurationKey.KeyIterator A specialized iterator class for tokenizing a configuration key.

Constructor Summary

ConfigurationKey()
Creates a new, empty instance of ConfigurationKey.

ConfigurationKey(String key)
Creates a new instance of ConfigurationKey and initializes it with the given key.

Method Summary

ConfigurationKey	append(String property) Appends the name of a property to this key.
ConfigurationKey	appendAttribute(String attr) Appends an attribute to this configuration key.
ConfigurationKey	appendIndex(int index) Appends an index to this configuration key.
static String	attributeName(String key) Extracts the name of the attribute from the given attribute key.
ConfigurationKey	commonKey(ConfigurationKey other) Returns a configuration key object that is initialized with the part of the key that is common to this key and the passed in key.
static String	constructAttributeKey(String key) Decorates the given key so that it represents an attribute.
ConfigurationKey	differenceKey(ConfigurationKey other) Returns the "difference key" to a given key.
boolean	equals(Object c) Checks if two ConfigurationKey objects are equal.
int	hashCode() Returns the hash code for this object.
static boolean	isAttributeKey(String key) Checks if the passed in key is an attribute key.
ConfigurationKey.KeyIterator	iterator() Returns an iterator for iterating over the single components of this configuration key.
int	length() Returns the actual length of this configuration key.
void	setLength(int len) Sets the new length of this configuration key.
String	toString() Returns a string representation of this object.

Methods inherited from class java.lang.Object

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

Constructor Detail

ConfigurationKey

public ConfigurationKey()

Creates a new, empty instance of ConfigurationKey.

ConfigurationKey

public ConfigurationKey(String key)

Creates a new instance of ConfigurationKey and initializes it with the given key.

Parameters:

key - the key as a string

Method Detail

append

public ConfigurationKey append(String property)

Appends the name of a property to this key. If necessary, a property delimiter will be added.

Parameters:

property - the name of the property to be added

Returns:

a reference to this object

appendIndex

public ConfigurationKey appendIndex(int index)

Appends an index to this configuration key.

Parameters:

index - the index to be appended

Returns:

a reference to this object

appendAttribute

public ConfigurationKey appendAttribute(String attr)

Appends an attribute to this configuration key.

Parameters:

attr - the name of the attribute to be appended

Returns:

a reference to this object

isAttributeKey

public static boolean isAttributeKey(String key)

Checks if the passed in key is an attribute key. Such attribute keys start and end with certain marker strings. In some cases they must be treated slightly different.

Parameters:

key - the key (part) to be checked

Returns:

a flag if this key is an attribute key

constructAttributeKey

public static String constructAttributeKey(String key)

Decorates the given key so that it represents an attribute. Adds special start and end markers.

Parameters:

key - the key to be decorated

Returns:

the decorated attribute key

attributeName

public static String attributeName(String key)

Extracts the name of the attribute from the given attribute key. This method removes the attribute markers - if any - from the specified key.

Parameters:

key - the attribute key

Returns:

the name of the corresponding attribute

toString

public String toString()

Returns a string representation of this object. This is the configuration key as a plain string.

Returns:

a string for this object

iterator

public ConfigurationKey.KeyIterator iterator()

Returns an iterator for iterating over the single components of this configuration key.

Returns:

an iterator for this key

length

public int length()

Returns the actual length of this configuration key.

Returns:

the length of this key

setLength

public void setLength(int len)

Sets the new length of this configuration key. With this method it is possible to truncate the key, e.g. to return to a state prior calling some append() methods. The semantic is the same as the setLength() method of StringBuffer.

Parameters:

len - the new length of the key

equals

public boolean equals(Object c)

Checks if two ConfigurationKey objects are equal. The method can be called with strings or other objects, too.

Parameters:

c - the object to compare

Returns:

a flag if both objects are equal

hashCode

public int hashCode()

Returns the hash code for this object.

Returns:

the hash code

commonKey

public ConfigurationKey commonKey(ConfigurationKey other)

Returns a configuration key object that is initialized with the part of the key that is common to this key and the passed in key.

Parameters:

other - the other key

Returns:

a key object with the common key part

differenceKey

public ConfigurationKey differenceKey(ConfigurationKey other)

Returns the "difference key" to a given key. This value is the part of the passed in key that differs from this key. There is the following relation: other = key.commonKey(other) + key.differenceKey(other) for an arbitrary configuration key key.

Parameters:

other - the key for which the difference is to be calculated

Returns:

the difference key