Module java.naming
Package javax.naming.directory

# Interface Attribute

All Superinterfaces:
  `Cloneable`, `Serializable`

All Known Implementing Classes:
  `BasicAttribute`

public interface Attribute extends Cloneable, Serializable
This interface represents an attribute associated with a named object.

In a directory, named objects can have associated with them attributes. The `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 `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 `getAttributeDefinition()` and `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 `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 `get()` and `getAll()`. to get the values dynamically from the directory.

Note that updates to `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 `DirContext` interface.

Since:
  1.3
See Also:
  - `BasicAttribute`

## Field Summary

Fields
Modifier and Type
Field
Description
`static final long`
`serialVersionUID`
Deprecated.
A `serialVersionUID` field in an interface is ineffectual.

## Method Summary

Modifier and Type
Method
Description
`void`
`add(int ix, Object attrVal)`
Adds an attribute value to the ordered list of attribute values.
`boolean`
`add(Object attrVal)`
Adds a new value to the attribute.
`void`
`clear()`
Removes all values from this attribute.
`Object`
`clone()`
Makes a copy of the attribute.
`boolean`
`contains(Object attrVal)`
Determines whether a value is in the attribute.
`Object`
`get()`
Retrieves one of this attribute's values.
`Object`
`get(int ix)`
Retrieves the attribute value from the ordered list of attribute values.
`NamingEnumeration<?>`
`getAll()`
Retrieves an enumeration of the attribute's values.
`DirContext`
`getAttributeDefinition()`
Retrieves the attribute's schema definition.
`DirContext`
`getAttributeSyntaxDefinition()`
Retrieves the syntax definition associated with the attribute.
`String`
`getID()`
Retrieves the id of this attribute.
`boolean`
`isOrdered()`
Determines whether this attribute's values are ordered.
`Object`
`remove(int ix)`
Removes an attribute value from the ordered list of attribute values.
`boolean`
`remove(Object attrval)`
Removes a specified value from the attribute.
`Object`
`set(int ix, Object attrVal)`
Sets an attribute value in the ordered list of attribute values.
`int`
`size()`
Retrieves the number of values in this attribute.

## Field Details

### serialVersionUID

@Deprecated static final long serialVersionUID
Deprecated.
A `serialVersionUID` field in an interface is ineffectual. Do not use; no replacement.
Use serialVersionUID from JNDI 1.1.1 for interoperability.

See Also:
  - Constant Field Values

## Method Details

### getAll

NamingEnumeration<?> getAll() throws NamingException
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.

Returns:
  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.
Throws:
  `NamingException` - If a naming exception was encountered while retrieving the values.
See Also:
  - `isOrdered()`

### get

Object get() 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.

Returns:
  A possibly null object representing one of the attribute's value. It is null if the attribute's value is null.
Throws:
  `NamingException` - If a naming exception was encountered while retrieving the value.
  `NoSuchElementException` - If this attribute has no values.

### size

int size()
Retrieves the number of values in this attribute.

Returns:
  The nonnegative number of values in this attribute.

### getID

String getID()
Retrieves the id of this attribute.

Returns:
  The id of this attribute. It cannot be null.

### contains

boolean contains(Object attrVal)
Determines whether a value is in the attribute. Equality is determined by the implementation, which may use `Object.equals()` or schema information to determine equality.

Parameters:
  `attrVal` - The possibly null value to check. If null, check whether the attribute has an attribute value whose value is null.
Returns:
  true if attrVal is one of this attribute's values; false otherwise.
See Also:
  - `Object.equals(java.lang.Object)`
  - `BasicAttribute.equals(java.lang.Object)`

### add

boolean add(Object attrVal)
Adds a new value to the attribute. If the attribute values are unordered and `attrVal` is already in the attribute, this method does nothing. If the attribute values are ordered, `attrVal` is added to the end of the list of attribute values.

Equality is determined by the implementation, which may use `Object.equals()` or schema information to determine equality.

Parameters:
  `attrVal` - The new possibly null value to add. If null, null is added as an attribute value.
Returns:
  true if a value was added; false otherwise.

### remove

boolean remove(Object attrval)
Removes a specified value from the attribute. If `attrval` is not in the attribute, this method does nothing. If the attribute values are ordered, the first occurrence of `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 `Object.equals()` or schema information to determine equality.

Parameters:
  `attrval` - The possibly null value to remove from this attribute. If null, remove the attribute value that is null.
Returns:
  true if the value was removed; false otherwise.

### clear

void clear()
Removes all values from this attribute.

### getAttributeSyntaxDefinition

DirContext getAttributeSyntaxDefinition() throws NamingException
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.

Returns:
  The attribute's syntax definition. Null if the implementation supports schemas but this particular attribute does not have any schema information.
Throws:
  `OperationNotSupportedException` - If getting the schema is not supported.
  `NamingException` - If a naming exception occurs while getting the schema.

### getAttributeDefinition

DirContext getAttributeDefinition() 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.

Returns:
  This attribute's schema definition. Null if the implementation supports schemas but this particular attribute does not have any schema information.
Throws:
  `OperationNotSupportedException` - If getting the schema is not supported.
  `NamingException` - If a naming exception occurs while getting the schema.

### clone

Object clone()
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.

Returns:
  A non-null copy of the attribute.

### isOrdered

boolean isOrdered()
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.

Returns:
  true if this attribute's values are ordered; false otherwise.
See Also:
  - `get(int)`
  - `remove(int)`
  - `add(int, java.lang.Object)`
  - `set(int, java.lang.Object)`

### get

Object get(int ix) throws NamingException
Retrieves the attribute value from the ordered list of attribute values. This method returns the value at the `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.

Parameters:
  `ix` - The index of the value in the ordered list of attribute values. `0 <= ix < size()`.
Returns:
  The possibly null attribute value at index `ix`; null if the attribute value is null.
Throws:
  `NamingException` - If a naming exception was encountered while retrieving the value.
  `IndexOutOfBoundsException` - If `ix` is outside the specified range.

### remove

Object remove(int ix)
Removes an attribute value from the ordered list of attribute values. This method removes the value at the `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 `ix` are shifted up towards the front of the list (and their indices decremented by one).

Parameters:
  `ix` - The index of the value to remove. `0 <= ix < size()`.
Returns:
  The possibly null attribute value at index `ix` that was removed; null if the attribute value is null.
Throws:
  `IndexOutOfBoundsException` - If `ix` is outside the specified range.

### add

void add(int ix, Object attrVal)
Adds an attribute value to the ordered list of attribute values. This method adds `attrVal` to the list of attribute values at index `ix`. Values located at indices at or greater than `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 `attrVal`, `IllegalStateException` is thrown.

Parameters:
  `ix` - The index in the ordered list of attribute values to add the new value. `0 <= ix <= size()`.
  `attrVal` - The possibly null attribute value to add; if null, null is the value added.
Throws:
  `IndexOutOfBoundsException` - If `ix` is outside the specified range.
  `IllegalStateException` - If the attribute values are unordered and `attrVal` is one of those values.

### set

Object set(int ix, Object attrVal)
Sets an attribute value in the ordered list of attribute values. This method sets the value at the `ix` index of the list of attribute values to be `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 `attrVal`, unless `attrVal` is already one of the values. In that case, `IllegalStateException` is thrown.

Parameters:
  `ix` - The index of the value in the ordered list of attribute values. `0 <= ix < size()`.
  `attrVal` - The possibly null attribute value to use. If null, 'null' replaces the old value.
Returns:
  The possibly null attribute value at index ix that was replaced. Null if the attribute value was null.
Throws:
  `IndexOutOfBoundsException` - If `ix` is outside the specified range.
  `IllegalStateException` - If `attrVal` already exists and the attribute values are unordered.