content/api/user-guide/6.35-value.mdtext

Title: 6.35 - Value
NavPrev: 6.34-syntax-checker.html
NavPrevText: 6.34 - SyntaxChecker
NavUp: 6-ldap-data-structures.html
NavUpText: 6 - LDAP data structures
NavNext: 7-requests-responses.html
NavNextText: 7 - Requests and Responses
Notice: Licensed to the Apache Software Foundation (ASF) under one
    or more contributor license agreements.  See the NOTICE file
    distributed with this work for additional information
    regarding copyright ownership.  The ASF licenses this file
    to you under the Apache License, Version 2.0 (the
    "License"); you may not use this file except in compliance
    with the License.  You may obtain a copy of the License at
    .
    http://www.apache.org/licenses/LICENSE-2.0
    .
    Unless required by applicable law or agreed to in writing,
    software distributed under the License is distributed on an
    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    KIND, either express or implied.  See the License for the
    specific language governing permissions and limitations
    under the License.

# 6.35 - Value

The _Value_ class is used to store an attribute's value. Such a value can be either a String or a byte[], depending on the nature of the AttributeType (the default is that the _Value_ is a String). Each value is associated to an AttributeType, and is used in an Entry or a DN.

We can create a schema aware _Value_, or just a plain _Value_. Having a schema aware _Value_ allows further controls to be made on the value injected : its syntax will be checked against the _AttributeType_ syntax.

_Value_ is also a _Externalizable_ class.

_Value_ instances are immutable.

## Creating a value

There are two ways to create a value:
- using a constructor
- using a static factory (useful for deserialization)

You can create the value passing it an *AttributeType*, or without it. Here are the possible constructors:

<CENTER>
| With an AttributeType | Without an attributeType | Description |
|:-:|:-:|:-:|
| Value( AttributeType, byte[] upValue ) | Value( byte[] upValue ) | Creates a Value with a binary content |
| Value( AttributeType, String upValue ) | Value( String upValue ) | Creates a Value with a String content |
| Value( AttributeType, Value ) | - | Create a new Value from an existing one, applying the SchemaManager on it |
</CENTER>

The third constructor is quite specific, as _Value_ is immutable, and it allows you to associate a SchemaManager to a _Value_ instance (creating a new _Value_ in the process). The new _Value_ instance will be schema aware.

## Operations on a Value

There are ways to consult the content of the _Value_, and its status. Here is the list of common operations:

<CENTER>
| Operation | Description |
|:-:|:-:|
| clone() | Clone the current Value, creating a new instance |
| compareTo( byte[] ) | Compare the content of the current value to the given byte[] |
| compareTo( String ) | Compare the content of the current value to the given String | 
| compareTo( Value ) | Compare the content of the current value to the given Value |
| deserialize( byte[], int ) | Create a Value deserializing it from the byte[], starting at a given position | 
| equals( Object ) | Tells if the current Value is equal to the provided object |
| getAttributeType() | Get back the AttributeType associated with this value, if any |
| getBytes() | Get the byte[] representation of this Value |
| getValue() | Get the Value as a String, if the Value is Human Readable |
| hashCode() | Compute the Value hashcode |
| isHumanReadable() | Tells if the Value is Humane Readable (ie, a String) |
| isInstanceOf( AttributeType ) | Tells if the Value is an instance of a given AttributeType, or of one of its parent |
| isNull() | Tells if the contained value is null |
| isSchemaAware() | Tells if teh Value is schema aware |
| isValid( SyntaxChecker ) | Check the contained value |
| length() | Returns the contained value's length (number of chars for a String, number of bytes for a byte[]) |
| readExternal( ObjectInput ) | Read a new Value from a stream of bytes |
| serialize( byte[], int ) | Write the Value into a stream of bytes |
| toString() | Returns a String representation of the Value instance  |
| writeExternal( ObjectOutput ) | Write the Value into a stream |
| 
</CENTER>