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

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.

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:

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:

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.

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:
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.