Chapter 11
The java.io Package

ByteArrayOutputStream

Name

Synopsis

Class Name:

java.io.ByteArrayOutputStream

Superclass:

java.io.FilterOutputStream

Immediate Subclasses:

None

Interfaces Implemented:

None

Availability:

JDK 1.0 or later

A ByteArrayOutputStream is a stream whose data is written to an internal byte array. None of the methods of this class throws an IOException because the data is written to an array instead of an actual I/O device.

The data for a ByteArrayOutputStream can be sent to another OutputStream using the writeTo() method. A copy of the array can be obtained using the toCharArray() method.

Class Summary

public class java.io.ByteArrayOutputStream extends java.io.OutputStream {
  // Variables
  protected byte[] buf;
  protected int count;

  // Constructors
  public ByteArrayOutputStream();
  public ByteArrayOutputStream(int size);
  // Instance Methods
  public synchronized void reset();
  public int size( );
  public synchronized byte[] toByteArray();
  public String toString();
  public String toString(int hibyte);            // Deprecated in 1.1
  public String toString(String enc);            // New in 1.1
  public synchronized void write(int b);
  public synchronized void write(byte[] b, int off, int len);
  public synchronized void writeTo(OutputStream out);
}

Variables

buf

protected byte[] buf

Description: The buffer that holds data for this stream.

count

protected int count

Description: A placeholder that marks the end of the data in the buffer.

Constructors

ByteArrayOutputStream

public ByteArrayOutputStream()

Description: This constructor creates a ByteArrayOutputStream with an internal buffer that has a default size of 32 bytes. The buffer grows automatically as data is written to the stream.

public ByteArrayOutputStream(int size)

Parameters

size: The initial buffer size.

Description

This constructor creates a ByteArrayOutputStream with an internal buffer that has a size of size bytes. The buffer grows automatically as data is written to the stream.

Instance Methods

reset

public synchronized void reset()

Description: This method discards the current contents of the buffer and resets the position of the stream to zero. Subsequent data is written starting at the beginning of the array.

size

public int size()

Description: This method returns the number of bytes currently stored in this object's internal buffer. It is a count of the number of bytes that have been written to the stream.

toByteArray

public synchronized byte[] toByteArray()

Returns

A copy of the data that has been written to this ByteArrayOutputStream.

Description

This method copies the data in the internal array and returns a reference to the copy. The returned array is as long as the data that has been written to the stream, i.e., the same as size().

toString

public String toString()

Returns

A copy of the data that has been written to this ByteArrayOutputStream.

Overrides

Object.toString()

Description

This method returns a reference to a String object that contains a copy of the bytes currently stored in this object's internal buffer. The bytes are assumed to represent characters in the encoding that is customary for the native platform, so the bytes are converted to Unicode characters based on that assumption.

public String toString(int hibyte)

Availability

Deprecated as of JDK 1.1

Parameters

hibyte: A value to use as the high byte of each character.

Returns

A copy of the data that has been written to this ByteArrayOutputStream, where each character in the string has a high byte of hibyte and a low byte taken from the corresponding byte in the array.

Description

This method provides a way to convert from bytes to characters. As of 1.1, it is deprecated and replaced with toString(String).

 public String toString(String enc) throws UnsupportedEncodingException

Availability

New as of JDK 1.1

Parameters

enc: The encoding scheme to use.

Returns

A copy of the data that has been written to this ByteArrayOutputStream, converted from bytes to characters via the named encoding scheme enc.

Throws

UnsupportedEncodingException: The specified encoding is not supported.

Description

This method returns a Java String created from the byte array of this stream. The conversion is performed according to the encoding scheme enc.

write

public synchronized void write(int b)

Parameters

b: The value to write.

Overrides

OutputStream.write(int)

Description

This method writes the low-order 8 bits of the given value into the internal array. If the array is full, a larger array is allocated.

public synchronized void write(byte b[], int off, int len)

Parameters

b

The array to copy from.

off

Offset into the byte array.

len

Number of bytes to write.

Overrides

OutputStream.write(byte[], int, int)

Description

This method copies len bytes to this object's internal array from b, starting oset elements from the beginning of the supplied array b. If the internal array is full, a larger array is allocated.

writeTo

 public synchronized void writeTo(OutputStream out) throws IOException

Parameters

out: The destination stream.

Throws

IOException: If any kind of I/O error occurs.

Description

This method writes the contents of this object's internal buffer to the given OutputStream. All the data that has been written to this ByteArrayOutputStream is written to out.

Inherited Methods

Method	Inherited From	Method	Inherited From
`clone()`	`Object`	`close()`	`OutputStream`
`equals(Object)`	`Object`	`finalize()`	`Object`
`flush()`	`OutputStream`	`getClass()`	`Object`
`hashCode()`	`Object`	`notify()`	`Object`
`notifyAll()`	`Object`	`wait()`	`Object`
`wait(long)`	`Object`	`wait(long, int)`	`Object`
`write(byte[])`	`OutputStream`