+ * In a directory, named objects can have associated with them + * attributes. The {@code Attribute} interface represents an attribute associated + * with a named object. An attribute contains 0 or more, possibly null, values. + * The attribute values can be ordered or unordered (see {@code isOrdered()}). + * If the values are unordered, no duplicates are allowed. + * If the values are ordered, duplicates are allowed. + *
+ * The content and representation of an attribute and its values is defined by + * the attribute's schema. The schema contains information + * about the attribute's syntax and other properties about the attribute. + * See {@code getAttributeDefinition()} and + * {@code getAttributeSyntaxDefinition()} + * for details regarding how to get schema information about an attribute + * if the underlying directory service supports schemas. + *
+ * Equality of two attributes is determined by the implementation class. + * A simple implementation can use {@code Object.equals()} to determine equality + * of attribute values, while a more sophisticated implementation might + * make use of schema information to determine equality. + * Similarly, one implementation might provide a static storage + * structure which simply returns the values passed to its + * constructor, while another implementation might define {@code get()} and + * {@code getAll()}. + * to get the values dynamically from the directory. + *
+ * Note that updates to {@code Attribute} (such as adding or removing a + * value) do not affect the corresponding representation of the attribute + * in the directory. Updates to the directory can only be effected + * using operations in the {@code DirContext} interface. + * + * @author Rosanna Lee + * @author Scott Seligman + * + * @see BasicAttribute + * @since 1.3 + */ +public interface Attribute extends Cloneable, java.io.Serializable { + /** + * Retrieves an enumeration of the attribute's values. + * The behaviour of this enumeration is unspecified + * if the attribute's values are added, changed, + * or removed while the enumeration is in progress. + * If the attribute values are ordered, the enumeration's items + * will be ordered. + * + * @return A non-null enumeration of the attribute's values. + * Each element of the enumeration is a possibly null Object. The object's + * class is the class of the attribute value. The element is null + * if the attribute's value is null. + * If the attribute has zero values, an empty enumeration + * is returned. + * @exception NamingException + * If a naming exception was encountered while retrieving + * the values. + * @see #isOrdered + */ + NamingEnumeration getAll() throws NamingException; + + /** + * Retrieves one of this attribute's values. + * If the attribute has more than one value and is unordered, any one of + * the values is returned. + * If the attribute has more than one value and is ordered, the + * first value is returned. + * + * @return A possibly null object representing one of + * the attribute's value. It is null if the attribute's value + * is null. + * @exception NamingException + * If a naming exception was encountered while retrieving + * the value. + * @exception java.util.NoSuchElementException + * If this attribute has no values. + */ + Object get() throws NamingException; + + /** + * Retrieves the number of values in this attribute. + * + * @return The nonnegative number of values in this attribute. + */ + int size(); + + /** + * Retrieves the id of this attribute. + * + * @return The id of this attribute. It cannot be null. + */ + String getID(); + + /** + * Determines whether a value is in the attribute. + * Equality is determined by the implementation, which may use + * {@code Object.equals()} or schema information to determine equality. + * + * @param attrVal The possibly null value to check. If null, check + * whether the attribute has an attribute value whose value is null. + * @return true if attrVal is one of this attribute's values; false otherwise. + * @see java.lang.Object#equals + * @see BasicAttribute#equals + */ + boolean contains(Object attrVal); + /** + * Adds a new value to the attribute. + * If the attribute values are unordered and + * {@code attrVal} is already in the attribute, this method does nothing. + * If the attribute values are ordered, {@code attrVal} is added to the end of + * the list of attribute values. + *
+ * Equality is determined by the implementation, which may use + * {@code Object.equals()} or schema information to determine equality. + * + * @param attrVal The new possibly null value to add. If null, null + * is added as an attribute value. + * @return true if a value was added; false otherwise. + */ + boolean add(Object attrVal); + + /** + * Removes a specified value from the attribute. + * If {@code attrval} is not in the attribute, this method does nothing. + * If the attribute values are ordered, the first occurrence of + * {@code attrVal} is removed and attribute values at indices greater + * than the removed + * value are shifted up towards the head of the list (and their indices + * decremented by one). + *
+ * Equality is determined by the implementation, which may use + * {@code Object.equals()} or schema information to determine equality. + * + * @param attrval The possibly null value to remove from this attribute. + * If null, remove the attribute value that is null. + * @return true if the value was removed; false otherwise. + */ + boolean remove(Object attrval); + + /** + * Removes all values from this attribute. + */ + void clear(); + + /** + * Retrieves the syntax definition associated with the attribute. + * An attribute's syntax definition specifies the format + * of the attribute's value(s). Note that this is different from + * the attribute value's representation as a Java object. Syntax + * definition refers to the directory's notion of syntax. + *
+ * For example, even though a value might be + * a Java String object, its directory syntax might be "Printable String" + * or "Telephone Number". Or a value might be a byte array, and its + * directory syntax is "JPEG" or "Certificate". + * For example, if this attribute's syntax is "JPEG", + * this method would return the syntax definition for "JPEG". + *
+ * The information that you can retrieve from a syntax definition + * is directory-dependent. + *
+ * If an implementation does not support schemas, it should throw + * OperationNotSupportedException. If an implementation does support + * schemas, it should define this method to return the appropriate + * information. + * @return The attribute's syntax definition. Null if the implementation + * supports schemas but this particular attribute does not have + * any schema information. + * @exception OperationNotSupportedException If getting the schema + * is not supported. + * @exception NamingException If a naming exception occurs while getting + * the schema. + */ + + DirContext getAttributeSyntaxDefinition() throws NamingException; + + /** + * Retrieves the attribute's schema definition. + * An attribute's schema definition contains information + * such as whether the attribute is multivalued or single-valued, + * the matching rules to use when comparing the attribute's values. + * + * The information that you can retrieve from an attribute definition + * is directory-dependent. + * + *
+ * If an implementation does not support schemas, it should throw + * OperationNotSupportedException. If an implementation does support + * schemas, it should define this method to return the appropriate + * information. + * @return This attribute's schema definition. Null if the implementation + * supports schemas but this particular attribute does not have + * any schema information. + * @exception OperationNotSupportedException If getting the schema + * is not supported. + * @exception NamingException If a naming exception occurs while getting + * the schema. + */ + DirContext getAttributeDefinition() throws NamingException; + + /** + * Makes a copy of the attribute. + * The copy contains the same attribute values as the original attribute: + * the attribute values are not themselves cloned. + * Changes to the copy will not affect the original and vice versa. + * + * @return A non-null copy of the attribute. + */ + Object clone(); + + //----------- Methods to support ordered multivalued attributes + + /** + * Determines whether this attribute's values are ordered. + * If an attribute's values are ordered, duplicate values are allowed. + * If an attribute's values are unordered, they are presented + * in any order and there are no duplicate values. + * @return true if this attribute's values are ordered; false otherwise. + * @see #get(int) + * @see #remove(int) + * @see #add(int, java.lang.Object) + * @see #set(int, java.lang.Object) + */ + boolean isOrdered(); + + /** + * Retrieves the attribute value from the ordered list of attribute values. + * This method returns the value at the {@code ix} index of the list of + * attribute values. + * If the attribute values are unordered, + * this method returns the value that happens to be at that index. + * @param ix The index of the value in the ordered list of attribute values. + * {@code 0 <= ix < size()}. + * @return The possibly null attribute value at index {@code ix}; + * null if the attribute value is null. + * @exception NamingException If a naming exception was encountered while + * retrieving the value. + * @exception IndexOutOfBoundsException If {@code ix} is outside the specified range. + */ + Object get(int ix) throws NamingException; + + /** + * Removes an attribute value from the ordered list of attribute values. + * This method removes the value at the {@code ix} index of the list of + * attribute values. + * If the attribute values are unordered, + * this method removes the value that happens to be at that index. + * Values located at indices greater than {@code ix} are shifted up towards + * the front of the list (and their indices decremented by one). + * + * @param ix The index of the value to remove. + * {@code 0 <= ix < size()}. + * @return The possibly null attribute value at index {@code ix} that was removed; + * null if the attribute value is null. + * @exception IndexOutOfBoundsException If {@code ix} is outside the specified range. + */ + Object remove(int ix); + + /** + * Adds an attribute value to the ordered list of attribute values. + * This method adds {@code attrVal} to the list of attribute values at + * index {@code ix}. + * Values located at indices at or greater than {@code ix} are + * shifted down towards the end of the list (and their indices incremented + * by one). + * If the attribute values are unordered and already have {@code attrVal}, + * {@code IllegalStateException} is thrown. + * + * @param ix The index in the ordered list of attribute values to add the new value. + * {@code 0 <= ix <= size()}. + * @param attrVal The possibly null attribute value to add; if null, null is + * the value added. + * @exception IndexOutOfBoundsException If {@code ix} is outside the specified range. + * @exception IllegalStateException If the attribute values are unordered and + * {@code attrVal} is one of those values. + */ + void add(int ix, Object attrVal); + + + /** + * Sets an attribute value in the ordered list of attribute values. + * This method sets the value at the {@code ix} index of the list of + * attribute values to be {@code attrVal}. The old value is removed. + * If the attribute values are unordered, + * this method sets the value that happens to be at that index + * to {@code attrVal}, unless {@code attrVal} is already one of the values. + * In that case, {@code IllegalStateException} is thrown. + * + * @param ix The index of the value in the ordered list of attribute values. + * {@code 0 <= ix < size()}. + * @param attrVal The possibly null attribute value to use. + * If null, 'null' replaces the old value. + * @return The possibly null attribute value at index ix that was replaced. + * Null if the attribute value was null. + * @exception IndexOutOfBoundsException If {@code ix} is outside the specified range. + * @exception IllegalStateException If {@code attrVal} already exists and the + * attribute values are unordered. + */ + Object set(int ix, Object attrVal); + + /** + * Use serialVersionUID from JNDI 1.1.1 for interoperability. + */ + static final long serialVersionUID = 8707690322213556804L; +}