ByteArrayOutputStream

AI-generated Key Takeaways

• ByteArrayOutputStream is an implementation of OutputStream that stores data in a dynamically growing byte array.

• Data written to the stream can be retrieved as a byte array using toByteArray() or as a String using toString().

• ByteArrayOutputStream can be reused by calling reset() which discards the current content and sets the size to zero.

• Closing a ByteArrayOutputStream has no effect and methods can still be called without causing exceptions.

public class ByteArrayOutputStream extends OutputStream

This class implements an output stream in which the data is written into a byte array. The buffer automatically grows as data is written to it. The data can be retrieved using toByteArray() and toString().

Closing a ByteArrayOutputStream has no effect. The methods in this class can be called after the stream has been closed without generating an IOException.

Field Summary

protected byte[]	buf	The buffer where data is stored.
protected int	count	The number of valid bytes in the buffer.

Public Constructor Summary

	ByteArrayOutputStream() Creates a new byte array output stream.
	ByteArrayOutputStream(int size) Creates a new byte array output stream, with a buffer capacity of the specified size, in bytes.

Public Method Summary

void	close() Closing a ByteArrayOutputStream has no effect.
synchronized void	reset() Resets the count field of this byte array output stream to zero, so that all currently accumulated output in the output stream is discarded.
synchronized int	size() Returns the current size of the buffer.
synchronized byte[]	toByteArray() Creates a newly allocated byte array.
synchronized String	toString(String charsetName) Converts the buffer's contents into a string by decoding the bytes using the named charset.
synchronized String	toString() Converts the buffer's contents into a string decoding bytes using the platform's default character set.
synchronized String	toString(int hibyte) This method is deprecated. This method does not properly convert bytes into characters. As of JDK 1.1, the preferred way to do this is via the toString(String enc) method, which takes an encoding-name argument, or the toString() method, which uses the platform's default character encoding.
synchronized void	write(byte[] b, int off, int len) Writes len bytes from the specified byte array starting at offset off to this byte array output stream.
synchronized void	write(int b) Writes the specified byte to this byte array output stream.
synchronized void	writeTo(OutputStream out) Writes the complete contents of this byte array output stream to the specified output stream argument, as if by calling the output stream's write method using out.write(buf, 0, count).

Inherited Method Summary

From class java.io.OutputStream

void	close() Closes this output stream and releases any system resources associated with this stream.
void	flush() Flushes this output stream and forces any buffered output bytes to be written out.
void	write(byte[] b) Writes b.length bytes from the specified byte array to this output stream.
void	write(byte[] b, int off, int len) Writes len bytes from the specified byte array starting at offset off to this output stream.
abstract void	write(int b) Writes the specified byte to this output stream.

From class java.lang.Object

Object	clone() Creates and returns a copy of this Object.
boolean	equals(Object obj) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of Class that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait(long timeout, int nanos) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait(long timeout) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait() Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object.

From interface java.io.Closeable

abstract void

close() Closes this stream and releases any system resources associated with it.

From interface java.io.Flushable

abstract void

flush() Flushes this stream by writing any buffered output to the underlying stream.

From interface java.lang.AutoCloseable

abstract void

close() Closes this resource, relinquishing any underlying resources.

Fields

protected byte[] buf

The buffer where data is stored.

protected int count

The number of valid bytes in the buffer.

Public Constructors

public ByteArrayOutputStream ()

Creates a new byte array output stream. The buffer capacity is initially 32 bytes, though its size increases if necessary.

public ByteArrayOutputStream (int size)

Creates a new byte array output stream, with a buffer capacity of the specified size, in bytes.

Parameters

size	the initial size.

Throws

IllegalArgumentException	if size is negative.

Public Methods

public void close ()

Closing a ByteArrayOutputStream has no effect. The methods in this class can be called after the stream has been closed without generating an IOException.

Throws

IOException

public synchronized void reset ()

Resets the count field of this byte array output stream to zero, so that all currently accumulated output in the output stream is discarded. The output stream can be used again, reusing the already allocated buffer space.

See Also

• ByteArrayInputStream.count

public synchronized int size ()

Returns the current size of the buffer.

Returns

• the value of the count field, which is the number of valid bytes in this output stream.

See Also

• count

public synchronized byte[] toByteArray ()

Creates a newly allocated byte array. Its size is the current size of this output stream and the valid contents of the buffer have been copied into it.

Returns

• the current contents of this output stream, as a byte array.

See Also

• size()

public synchronized String toString (String charsetName)

Converts the buffer's contents into a string by decoding the bytes using the named charset. The length of the new String is a function of the charset, and hence may not be equal to the length of the byte array.

This method always replaces malformed-input and unmappable-character sequences with this charset's default replacement string. The CharsetDecoder class should be used when more control over the decoding process is required.

Parameters

charsetName	the name of a supported charset

Returns

• String decoded from the buffer's contents.

Throws

UnsupportedEncodingException	If the named charset is not supported

public synchronized String toString ()

Converts the buffer's contents into a string decoding bytes using the platform's default character set. The length of the new String is a function of the character set, and hence may not be equal to the size of the buffer.

This method always replaces malformed-input and unmappable-character sequences with the default replacement string for the platform's default character set. The {@linkplain java.nio.charset.CharsetDecoder} class should be used when more control over the decoding process is required.

Returns

• String decoded from the buffer's contents.

public synchronized String toString (int hibyte)

This method is deprecated.
This method does not properly convert bytes into characters. As of JDK 1.1, the preferred way to do this is via the toString(String enc) method, which takes an encoding-name argument, or the toString() method, which uses the platform's default character encoding.

Creates a newly allocated string. Its size is the current size of the output stream and the valid contents of the buffer have been copied into it. Each character c in the resulting string is constructed from the corresponding element b in the byte array such that:

     c == (char)(((hibyte & 0xff) << 8) | (b & 0xff))
 

Parameters

hibyte	the high byte of each resulting Unicode character.

Returns

• the current contents of the output stream, as a string.

See Also

• size()
• toString(String)
• toString()

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

Writes len bytes from the specified byte array starting at offset off to this byte array output stream.

Parameters

b	the data.
off	the start offset in the data.
len	the number of bytes to write.

public synchronized void write (int b)

Writes the specified byte to this byte array output stream.

Parameters

b	the byte to be written.

public synchronized void writeTo (OutputStream out)

Writes the complete contents of this byte array output stream to the specified output stream argument, as if by calling the output stream's write method using out.write(buf, 0, count).

Parameters

out	the output stream to which to write the data.

Throws

IOException	if an I/O error occurs.