window.runtime propertywindow.runtime.flash.utils.ByteArray
Runtime Versions:  1.0

The ByteArray class provides methods and properties to optimize reading, writing, and working with binary data.

Note: The ByteArray class is for advanced developers who need to access data on the byte level.

In-memory data is a packed array (the most compact representation for the data type) of bytes, but an instance of the ByteArray class can be manipulated with the standard [] (array access) operators. It also can be read and written to as an in-memory file, using methods similar to those in the URLStream and Socket classes.

In addition, zlib compression and decompression are supported, as well as Action Message Format (AMF) object serialization.

Possible uses of the ByteArray class include the following:

See also

Socket class
URLStream class

Properties
 PropertyDefined By
  bytesAvailable : uint
[read-only] The number of bytes of data available for reading from the current position in the byte array to the end of the array.
ByteArray
  defaultObjectEncoding : uint
[static] Denotes the default object encoding for the ByteArray class to use for a new ByteArray instance.
ByteArray
  endian : String
Changes or reads the byte order for the data; either Endian.BIG_ENDIAN or Endian.LITTLE_ENDIAN.
ByteArray
  length : uint
The length of the ByteArray object, in bytes.
ByteArray
  objectEncoding : uint
Used to determine whether the ActionScript 3.0, ActionScript 2.0, or ActionScript 1.0 format should be used when writing to, or reading from, a ByteArray instance.
ByteArray
  position : uint
Moves, or returns the current position, in bytes, of the file pointer into the ByteArray object.
ByteArray
Public Methods
 MethodDefined By
  
ByteArray()
Creates a ByteArray instance representing a packed array of bytes, so that you can use the methods and properties in this class to optimize your data storage and stream.
ByteArray
  
clear():void
Clears the contents of the byte array and resets the length and position properties to 0.
ByteArray
  
compress(algorithm:String):void
Compresses the byte array.
ByteArray
  
deflate():void
Compresses the byte array using the deflate compression algorithm.
ByteArray
  
inflate():void
Decompresses the byte array using the deflate compression algorithm.
ByteArray
  
readBoolean():Boolean
Reads a Boolean value from the byte stream.
ByteArray
  
readByte():int
Reads a signed byte from the byte stream.
ByteArray
  
readBytes(bytes:ByteArray, offset:uint = 0, length:uint = 0):void
Reads the number of data bytes, specified by the length parameter, from the byte stream.
ByteArray
  
readDouble():Number
Reads an IEEE 754 double-precision (64-bit) floating-point number from the byte stream.
ByteArray
  
readFloat():Number
Reads an IEEE 754 single-precision (32-bit) floating-point number from the byte stream.
ByteArray
  
readInt():int
Reads a signed 32-bit integer from the byte stream.
ByteArray
  
readMultiByte(length:uint, charSet:String):String
Reads a multibyte string of specified length from the byte stream using the specified character set.
ByteArray
  
readObject():*
Reads an object from the byte array, encoded in AMF serialized format.
ByteArray
  
readShort():int
Reads a signed 16-bit integer from the byte stream.
ByteArray
  
readUnsignedByte():uint
Reads an unsigned byte from the byte stream.
ByteArray
  
readUnsignedInt():uint
Reads an unsigned 32-bit integer from the byte stream.
ByteArray
  
readUnsignedShort():uint
Reads an unsigned 16-bit integer from the byte stream.
ByteArray
  
readUTF():String
Reads a UTF-8 string from the byte stream.
ByteArray
  
readUTFBytes(length:uint):String
Reads a sequence of UTF-8 bytes specified by the length parameter from the byte stream and returns a string.
ByteArray
  
toString():String
Converts the byte array to a string.
ByteArray
  
uncompress(algorithm:String):void
Decompresses the byte array.
ByteArray
  
writeBoolean(value:Boolean):void
Writes a Boolean value.
ByteArray
  
writeByte(value:int):void
Writes a byte to the byte stream.
ByteArray
  
writeBytes(bytes:ByteArray, offset:uint = 0, length:uint = 0):void
Writes a sequence of length bytes from the specified byte array, bytes, starting offset (zero-based index) bytes into the byte stream.
ByteArray
  
writeDouble(value:Number):void
Writes an IEEE 754 double-precision (64-bit) floating-point number to the byte stream.
ByteArray
  
writeFloat(value:Number):void
Writes an IEEE 754 single-precision (32-bit) floating-point number to the byte stream.
ByteArray
  
writeInt(value:int):void
Writes a 32-bit signed integer to the byte stream.
ByteArray
  
writeMultiByte(value:String, charSet:String):void
Writes a multibyte string to the byte stream using the specified character set.
ByteArray
  
writeObject(object:*):void
Writes an object into the byte array in AMF serialized format.
ByteArray
  
writeShort(value:int):void
Writes a 16-bit integer to the byte stream.
ByteArray
  
writeUnsignedInt(value:uint):void
Writes a 32-bit unsigned integer to the byte stream.
ByteArray
  
writeUTF(value:String):void
Writes a UTF-8 string to the byte stream.
ByteArray
  
writeUTFBytes(value:String):void
Writes a UTF-8 string to the byte stream.
ByteArray
Property Detail
bytesAvailableproperty
bytesAvailable:uint  [read-only]
Runtime Versions:  1.0

The number of bytes of data available for reading from the current position in the byte array to the end of the array.

Use the bytesAvailable property in conjunction with the read methods each time you access a ByteArray object to ensure that you are reading valid data.

defaultObjectEncodingproperty 
defaultObjectEncoding:uint
Runtime Versions:  1.0

Denotes the default object encoding for the ByteArray class to use for a new ByteArray instance. When you create a new ByteArray instance, the encoding on that instance starts with the value of defaultObjectEncoding. The defaultObjectEncoding property is initialized to ObjectEncoding.AMF3.

When an object is written to or read from binary data, the objectEncoding value is used to determine whether the ActionScript 3.0, ActionScript2.0, or ActionScript 1.0 format should be used. The value is a constant from the ObjectEncoding class.

See also

ObjectEncoding class
ByteArray.objectEncoding
endianproperty 
endian:String
Runtime Versions:  1.0

Changes or reads the byte order for the data; either Endian.BIG_ENDIAN or Endian.LITTLE_ENDIAN.

See also

Endian class
lengthproperty 
length:uint
Runtime Versions:  1.0

The length of the ByteArray object, in bytes.

If the length is set to a value that is larger than the current length, the the right side of the byte array is filled with zeros.

If the length is set to a value that is smaller than the current length, the byte array is truncated.

objectEncodingproperty 
objectEncoding:uint
Runtime Versions:  1.0

Used to determine whether the ActionScript 3.0, ActionScript 2.0, or ActionScript 1.0 format should be used when writing to, or reading from, a ByteArray instance. The value is a constant from the ObjectEncoding class.

See also

ObjectEncoding class
ByteArray.defaultObjectEncoding
positionproperty 
position:uint
Runtime Versions:  1.0

Moves, or returns the current position, in bytes, of the file pointer into the ByteArray object. This is the point at which the next call to a read method starts reading or a write method starts writing.

Constructor Detail
ByteArray()Constructor
function ByteArray()
Runtime Versions:  1.0

Creates a ByteArray instance representing a packed array of bytes, so that you can use the methods and properties in this class to optimize your data storage and stream.

Method Detail
clear()method
function clear():void
Runtime Versions:  1.5

Clears the contents of the byte array and resets the length and position properties to 0. Calling this method explicitly frees up the memory used by the ByteArray instance.

compress()method 
function compress(algorithm:String):void

Compresses the byte array. The entire byte array is compressed. For content running in Adobe AIR, you can specify a compression algorithm by passing a value (defined in the CompressionAlgorithm class) as the algorithm parameter.

After the call, the length property of the ByteArray is set to the new length. The position property is set to the end of the byte array.

The zlib compressed data format is described at http://www.ietf.org/rfc/rfc1950.txt.

The deflate compression algorithm is described at http://www.ietf.org/rfc/rfc1951.txt.

The deflate compression algorithm is used in several compression formats, such as zlib, gzip, some zip implementations, and others. When data is compressed using one of those compression formats, in addition to storing the compressed version of the original data, the compression format data (for example, the .zip file) includes metadata information. Some examples of the types of metadata included in various file formats are file name, file modification date/time, original file size, optional comments, checksum data, and more.

For example, when a ByteArray is compressed using the zlib algorithm, the resulting ByteArray is structured in a specific format. Certain bytes contain metadata about the compressed data, while other bytes contain the actual compressed version of the original ByteArray data. As defined by the zlib compressed data format specification, those bytes (that is, the portion containing the compressed version of the original data) are compressed using the deflate algorithm. Consequently those bytes are identical to the result of calling compress(CompressionAlgorithm.DEFLATE) on the original ByteArray. However, the result from compress(CompressionAlgorithm.ZLIB) includes the extra metadata, while the compress(air.CompressionAlgorithm.DEFLATE) result includes only the compressed version of the original ByteArray data and nothing else.

In order to use the deflate format to compress a ByteArray instance's data in a specific format such as gzip or zip, you cannot simply call compress(air.CompressionAlgorithm.DEFLATE). You must create a ByteArray structured according to the compression format's specification, including the appropriate metadata as well as the compressed data obtained using the deflate format. Likewise, in order to decode data compressed in a format such as gzip or zip, you can't simply call uncompress(air.CompressionAlgorithm.DEFLATE) on that data. First, you must separate the metadata from the compressed data, and you can then use the deflate format to decompress the compressed data.

Parameters

algorithm:String (default = NaN) — The compression algorithm to use when compressing. Valid values are defined as constants in the CompressionAlgorithm class. The default is to use zlib format. Calling compress(air.CompressionAlgorithm.DEFLATE) has the same effect as calling the deflate() method.

See also

uncompress()
CompressionAlgorithm
deflate()method 
function deflate():void
Runtime Versions:  1.5

Compresses the byte array using the deflate compression algorithm. The entire byte array is compressed.

After the call, the length property of the ByteArray is set to the new length. The position property is set to the end of the byte array.

The deflate compression algorithm is described at http://www.ietf.org/rfc/rfc1951.txt.

In order to use the deflate format to compress a ByteArray instance's data in a specific format such as gzip or zip, you cannot simply call deflate(). You must create a ByteArray structured according to the compression format's specification, including the appropriate metadata as well as the compressed data obtained using the deflate format. Likewise, in order to decode data compressed in a format such as gzip or zip, you can't simply call inflate() on that data. First, you must separate the metadata from the compressed data, and you can then use the deflate format to decompress the compressed data.

See also

inflate()
inflate()method 
function inflate():void
Runtime Versions:  1.0

Decompresses the byte array using the deflate compression algorithm. The byte array must have been compressed using the same algorithm.

After the call, the length property of the ByteArray is set to the new length. The position property is set to 0.

The deflate compression algorithm is described at http://www.ietf.org/rfc/rfc1951.txt.

In order to decode data compressed in a format that uses the deflate compression algorithm, such as data in gzip or zip format, it will not work to simply call inflate() on a ByteArray containing the compression formation data. First, you must separate the metadata that is included as part of the compressed data format from the actual compressed data. For more information, see the compress() method description.


Throws
IOError — The data is not valid compressed data; it was not compressed with the same compression algorithm used to compress.

See also

deflate()
readBoolean()method 
function readBoolean():Boolean
Runtime Versions:  1.0

Reads a Boolean value from the byte stream. A single byte is read, and true is returned if the byte is nonzero, false otherwise.

Returns
Boolean — Returns true if the byte is nonzero, false otherwise.

Throws
EOFError — There is not sufficient data available to read.
readByte()method 
function readByte():int
Runtime Versions:  1.0

Reads a signed byte from the byte stream.

The returned value is in the range -128 to 127.

Returns
int — An integer between -128 and 127.

Throws
EOFError — There is not sufficient data available to read.
readBytes()method 
function readBytes(bytes:ByteArray, offset:uint = 0, length:uint = 0):void
Runtime Versions:  1.0

Reads the number of data bytes, specified by the length parameter, from the byte stream. The bytes are read into the ByteArray object specified by the bytes parameter, and the bytes are written into the destination ByteArray starting at the position specified by offset.

Parameters

bytes:ByteArray — The ByteArray object to read data into.
 
offset:uint (default = 0) — The offset (position) in bytes at which the read data should be written.
 
length:uint (default = 0) — The number of bytes to read. The default value of 0 causes all available data to be read.


Throws
EOFError — There is not sufficient data available to read.
readDouble()method 
function readDouble():Number
Runtime Versions:  1.0

Reads an IEEE 754 double-precision (64-bit) floating-point number from the byte stream.

Returns
Number — A double-precision (64-bit) floating-point number.

Throws
EOFError — There is not sufficient data available to read.
readFloat()method 
function readFloat():Number
Runtime Versions:  1.0

Reads an IEEE 754 single-precision (32-bit) floating-point number from the byte stream.

Returns
Number — A single-precision (32-bit) floating-point number.

Throws
EOFError — There is not sufficient data available to read.
readInt()method 
function readInt():int
Runtime Versions:  1.0

Reads a signed 32-bit integer from the byte stream.

The returned value is in the range -2147483648 to 2147483647.

Returns
int — A 32-bit signed integer between -2147483648 and 2147483647.

Throws
EOFError — There is not sufficient data available to read.
readMultiByte()method 
function readMultiByte(length:uint, charSet:String):String
Runtime Versions:  1.0

Reads a multibyte string of specified length from the byte stream using the specified character set.

Parameters

length:uint — The number of bytes from the byte stream to read.
 
charSet:String — The string denoting the character set to use to interpret the bytes. Possible character set strings include "shift-jis", "cn-gb", "iso-8859-1", and others. For a complete list, see Supported Character Sets.

Note: If the value for the charSet parameter is not recognized by the current system, the application uses the system's default code page as the character set. For example, a value for the charSet parameter, as in myTest.readMultiByte(22, "iso-8859-01") that uses 01 instead of 1 might work on your development machine, but not on another machine. On the other machine, the application will use the system's default code page.

Returns
String — UTF-8 encoded string.

Throws
EOFError — There is not sufficient data available to read.
readObject()method 
function readObject():*
Runtime Versions:  1.0

Reads an object from the byte array, encoded in AMF serialized format.

Returns
* — The deserialized object.

Throws
EOFError — There is not sufficient data available to read.
readShort()method 
function readShort():int
Runtime Versions:  1.0

Reads a signed 16-bit integer from the byte stream.

The returned value is in the range -32768 to 32767.

Returns
int — A 16-bit signed integer between -32768 and 32767.

Throws
EOFError — There is not sufficient data available to read.
readUnsignedByte()method 
function readUnsignedByte():uint
Runtime Versions:  1.0

Reads an unsigned byte from the byte stream.

The returned value is in the range 0 to 255.

Returns
uint — A 32-bit unsigned integer between 0 and 255.

Throws
EOFError — There is not sufficient data available to read.
readUnsignedInt()method 
function readUnsignedInt():uint
Runtime Versions:  1.0

Reads an unsigned 32-bit integer from the byte stream.

The returned value is in the range 0 to 4294967295.

Returns
uint — A 32-bit unsigned integer between 0 and 4294967295.

Throws
EOFError — There is not sufficient data available to read.
readUnsignedShort()method 
function readUnsignedShort():uint
Runtime Versions:  1.0

Reads an unsigned 16-bit integer from the byte stream.

The returned value is in the range 0 to 65535.

Returns
uint — A 16-bit unsigned integer between 0 and 65535.

Throws
EOFError — There is not sufficient data available to read.
readUTF()method 
function readUTF():String
Runtime Versions:  1.0

Reads a UTF-8 string from the byte stream. The string is assumed to be prefixed with an unsigned short indicating the length in bytes.

Returns
String — UTF-8 encoded string.

Throws
EOFError — There is not sufficient data available to read.
readUTFBytes()method 
function readUTFBytes(length:uint):String
Runtime Versions:  1.0

Reads a sequence of UTF-8 bytes specified by the length parameter from the byte stream and returns a string.

Parameters

length:uint — An unsigned short indicating the length of the UTF-8 bytes.

Returns
String — A string composed of the UTF-8 bytes of the specified length.

Throws
EOFError — There is not sufficient data available to read.
toString()method 
function toString():String
Runtime Versions:  1.0

Converts the byte array to a string. If the data in the array begins with a Unicode byte order mark, the application will honor that mark when converting to a string. If System.useCodePage is set to true, the application will treat the data in the array as being in the current system code page when converting.

Returns
String — The string representation of the byte array.
uncompress()method 
function uncompress(algorithm:String):void
Runtime Versions:  1.0

Decompresses the byte array. For content running in Adobe AIR, you can specify a compression algorithm by passing a value (defined in the CompressionAlgorithm class) as the algorithm parameter. The byte array must have been compressed using the same algorithm.

After the call, the length property of the ByteArray is set to the new length. The position property is set to 0.

The zlib compressed data format is described at http://www.ietf.org/rfc/rfc1950.txt.

The deflate compression algorithm is described at http://www.ietf.org/rfc/rfc1951.txt.

In order to decode data compressed in a format that uses the deflate compression algorithm, such as data in gzip or zip format, it will not work to call uncompress(CompressionAlgorithm.DEFLATE) on a ByteArray containing the compression formation data. First, you must separate the metadata that is included as part of the compressed data format from the actual compressed data. For more information, see the compress() method description.

Parameters

algorithm:String (default = NaN) — The compression algorithm to use when decompressing. This must be the same compression algorithm used to compress the data. Valid values are defined as constants in the CompressionAlgorithm class. The default is to use zlib format. This parameter is only recognized for content running in Adobe AIR.


Throws
IOError — The data is not valid compressed data; it was not compressed with the same compression algorithm used to compress.

See also

compress()
CompressionAlgorithm
writeBoolean()method 
function writeBoolean(value:Boolean):void
Runtime Versions:  1.0

Writes a Boolean value. A single byte is written according to the value parameter, either 1 if true or 0 if false.

Parameters

value:Boolean — A Boolean value determining which byte is written. If the parameter is true, the method writes a 1; if false, the method writes a 0.

writeByte()method 
function writeByte(value:int):void
Runtime Versions:  1.0

Writes a byte to the byte stream.

The low 8 bits of the parameter are used. The high 24 bits are ignored.

Parameters

value:int — A 32-bit integer. The low 8 bits are written to the byte stream.

writeBytes()method 
function writeBytes(bytes:ByteArray, offset:uint = 0, length:uint = 0):void
Runtime Versions:  1.0

Writes a sequence of length bytes from the specified byte array, bytes, starting offset (zero-based index) bytes into the byte stream.

If the length parameter is omitted, the default length of 0 is used; the method writes the entire buffer starting at offset. If the offset parameter is also omitted, the entire buffer is written.

If offset or length is out of range, they are clamped to the beginning and end of the bytes array.

Parameters

bytes:ByteArray — The ByteArray object.
 
offset:uint (default = 0) — A zero-based index indicating the position into the array to begin writing.
 
length:uint (default = 0) — An unsigned integer indicating how far into the buffer to write.

writeDouble()method 
function writeDouble(value:Number):void
Runtime Versions:  1.0

Writes an IEEE 754 double-precision (64-bit) floating-point number to the byte stream.

Parameters

value:Number — A double-precision (64-bit) floating-point number.

writeFloat()method 
function writeFloat(value:Number):void
Runtime Versions:  1.0

Writes an IEEE 754 single-precision (32-bit) floating-point number to the byte stream.

Parameters

value:Number — A single-precision (32-bit) floating-point number.

writeInt()method 
function writeInt(value:int):void
Runtime Versions:  1.0

Writes a 32-bit signed integer to the byte stream.

Parameters

value:int — An integer to write to the byte stream.

writeMultiByte()method 
function writeMultiByte(value:String, charSet:String):void
Runtime Versions:  1.0

Writes a multibyte string to the byte stream using the specified character set.

Parameters

value:String — The string value to be written.
 
charSet:String — The string denoting the character set to use. Possible character set strings include "shift-jis", "cn-gb", "iso-8859-1", and others. For a complete list, see Supported Character Sets.

writeObject()method 
function writeObject(object:*):void
Runtime Versions:  1.0

Writes an object into the byte array in AMF serialized format.

Parameters

object:* — The object to serialize.

writeShort()method 
function writeShort(value:int):void
Runtime Versions:  1.0

Writes a 16-bit integer to the byte stream. The low 16 bits of the parameter are used. The high 16 bits are ignored.

Parameters

value:int — 32-bit integer, whose low 16 bits are written to the byte stream.

writeUnsignedInt()method 
function writeUnsignedInt(value:uint):void
Runtime Versions:  1.0

Writes a 32-bit unsigned integer to the byte stream.

Parameters

value:uint — An unsigned integer to write to the byte stream.

writeUTF()method 
function writeUTF(value:String):void
Runtime Versions:  1.0

Writes a UTF-8 string to the byte stream. The length of the UTF-8 string in bytes is written first, as a 16-bit integer, followed by the bytes representing the characters of the string.

Parameters

value:String — The string value to be written.


Throws
— If the length is larger than 65535.
writeUTFBytes()method 
function writeUTFBytes(value:String):void
Runtime Versions:  1.0

Writes a UTF-8 string to the byte stream. Similar to the writeUTF() method, but writeUTFBytes() does not prefix the string with a 16-bit length word.

Parameters

value:String — The string value to be written.




© 2009 Adobe Systems Incorporated. All rights reserved.
Fri Feb 20 2009, 11:31 AM -08:00