Added in API level 1

Summary: Fields | Ctors | Methods | Inherited Methods

ByteArrayOutputStream

public class ByteArrayOutputStream
extends OutputStream

java.lang.Object
↳	java.io.OutputStream
	↳	java.io.ByteArrayOutputStream

---

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.

Summary

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

Public constructors
ByteArrayOutputStream() Creates a new ByteArrayOutputStream.
ByteArrayOutputStream(int size) Creates a new ByteArrayOutputStream, with a buffer capacity of the specified size, in bytes.

Public methods
void	close() Closing a ByteArrayOutputStream has no effect.
void	reset() Resets the count field of this ByteArrayOutputStream to zero, so that all currently accumulated output in the output stream is discarded.
int	size() Returns the current size of the buffer.
byte[]	toByteArray() Creates a newly allocated byte array.
String	toString(String charsetName) Converts the buffer's contents into a string by decoding the bytes using the named charset.
String	toString(Charset charset) Converts the buffer's contents into a string by decoding the bytes using the specified charset.
String	toString() Converts the buffer's contents into a string decoding bytes using the platform's default character set.
String	toString(int hibyte) This method was deprecated in API level 15. This method does not properly convert bytes into characters. As of JDK 1.1, the preferred way to do this is via the toString(java.lang.String) or toString(java.nio.charset.Charset) method, which takes an encoding-name or charset argument, or the toString() method, which uses the platform's default character encoding.
void	write(byte[] b, int off, int len) Writes len bytes from the specified byte array starting at offset off to this ByteArrayOutputStream.
void	write(int b) Writes the specified byte to this ByteArrayOutputStream.
void	writeBytes(byte[] b) Writes the complete contents of the specified byte array to this ByteArrayOutputStream.
void	writeTo(OutputStream out) Writes the complete contents of this ByteArrayOutputStream to the specified output stream argument, as if by calling the output stream's write method using out.write(buf, 0, count).

Inherited methods
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. static OutputStream nullOutputStream() Returns a new OutputStream which discards all bytes. 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) Indicates whether some other object is "equal to" this one. void finalize() Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. final Class<?> getClass() Returns the runtime class of this Object. int hashCode() Returns a hash code value for the object. final void notify() Wakes up a single thread that is waiting on this object's monitor. final void notifyAll() Wakes up all threads that are waiting on this object's monitor. String toString() Returns a string representation of the object. final void wait(long timeoutMillis, int nanos) Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed. final void wait(long timeoutMillis) Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed. final void wait() Causes the current thread to wait until it is awakened, typically by being notified or interrupted.
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

buf

Added in API level 1

protected byte[] buf

The buffer where data is stored.

count

Added in API level 1

protected int count

The number of valid bytes in the buffer.

Public constructors

ByteArrayOutputStream

Added in API level 1

public ByteArrayOutputStream ()

Creates a new ByteArrayOutputStream. The buffer capacity is initially 32 bytes, though its size increases if necessary.

ByteArrayOutputStream

Added in API level 1

public ByteArrayOutputStream (int size)

Creates a new ByteArrayOutputStream, with a buffer capacity of the specified size, in bytes.

Parameters
size	int: the initial size.

Throws
IllegalArgumentException	if size is negative.

Public methods

close

Added in API level 1

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

reset

Added in API level 1

public void reset ()

Resets the count field of this ByteArrayOutputStream 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

size

Added in API level 1

public int size ()

Returns the current size of the buffer.

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

See also:

• count

toByteArray

Added in API level 1

public 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
byte[]	the current contents of this output stream, as a byte array.

See also:

• size()

toString

Added in API level 1

public String toString (String charsetName)

Converts the buffer's contents into a string by decoding the bytes using the named charset.

This method is equivalent to #toString(charset) that takes a charset.

An invocation of this method of the form

 ByteArrayOutputStream b = ...
      b.toString("UTF-8")
      
 

behaves in exactly the same way as the expression

 ByteArrayOutputStream b = ...
      b.toString(StandardCharsets.UTF_8)
      
 

Parameters
charsetName	String: the name of a supported charset

Returns
String	String decoded from the buffer's contents.

Throws
UnsupportedEncodingException	If the named charset is not supported

toString

Added in API level 33

public String toString (Charset charset)

Converts the buffer's contents into a string by decoding the bytes using the specified 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 the charset's default replacement string. The CharsetDecoder class should be used when more control over the decoding process is required.

Parameters
charset	Charset: the charset to be used to decode the bytes

Returns
String	String decoded from the buffer's contents.

toString

Added in API level 1

public 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 CharsetDecoder class should be used when more control over the decoding process is required.

Returns
String	String decoded from the buffer's contents.

toString

Added in API level 1
Deprecated in API level 15

public String toString (int hibyte)

This method was deprecated in API level 15.
This method does not properly convert bytes into characters. As of JDK 1.1, the preferred way to do this is via the toString(java.lang.String) or toString(java.nio.charset.Charset) method, which takes an encoding-name or charset 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	int: the high byte of each resulting Unicode character.

Returns
String	the current contents of the output stream, as a string.

See also:

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

write

Added in API level 1

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

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

Parameters
b	byte: the data.
off	int: the start offset in the data.
len	int: the number of bytes to write.

Throws
NullPointerException	if b is null.
IndexOutOfBoundsException	if off is negative, len is negative, or len is greater than b.length - off

write

Added in API level 1

public void write (int b)

Writes the specified byte to this ByteArrayOutputStream.

Parameters
b	int: the byte to be written.

writeBytes

Added in API level 33

public void writeBytes (byte[] b)

Writes the complete contents of the specified byte array to this ByteArrayOutputStream.

API Note:

• This method is equivalent to write(b, 0, b.length).

Parameters
b	byte: the data.

Throws
NullPointerException	if b is null.

writeTo

Added in API level 1

public void writeTo (OutputStream out)

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

Parameters
out	OutputStream: the output stream to which to write the data.

Throws
NullPointerException	if out is null.
IOException	if an I/O error occurs.