ByteArrayOutputStream (Java SE 9 & JDK 9 ) (original) (raw)

• java.lang.Object

• • java.io.OutputStream
  • • java.io.ByteArrayOutputStream

• All Implemented Interfaces:
  [Closeable](../../java/io/Closeable.html "interface in java.io"), [Flushable](../../java/io/Flushable.html "interface in java.io"), [AutoCloseable](../../java/lang/AutoCloseable.html "interface in java.lang")

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() andtoString().
Closing a ByteArrayOutputStream has no effect. The methods in this class can be called after the stream has been closed without generating an IOException.
Since:
1.0

• • Field Summary

  Fields

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

  • Constructor Summary

  Constructors

  Constructor	Description
  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.

  • Method Summary

  All Methods Instance Methods Concrete Methods Deprecated Methods

  Modifier and Type	Method	Description
  void	close​()	Closing a ByteArrayOutputStream has no effect.
  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.
  int	size​()	Returns the current size of the buffer.
  byte[]	toByteArray​()	Creates a newly allocated byte array.
  String	toString​()	Converts the buffer's contents into a string decoding bytes using the platform's default character set.
  String	toString​(int hibyte)	Deprecated.
  String	toString​(String charsetName)	Converts the buffer's contents into a string by decoding the bytes using the named charset.
  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.
  void	write​(int b)	Writes the specified byte to this byte array output stream.
  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).

     * ### Methods inherited from class java.lang.[Object](../../java/lang/Object.html "class in java.lang")  
     `[clone](../../java/lang/Object.html#clone--), [equals](../../java/lang/Object.html#equals-java.lang.Object-), [finalize](../../java/lang/Object.html#finalize--), [getClass](../../java/lang/Object.html#getClass--), [hashCode](../../java/lang/Object.html#hashCode--), [notify](../../java/lang/Object.html#notify--), [notifyAll](../../java/lang/Object.html#notifyAll--), [wait](../../java/lang/Object.html#wait--), [wait](../../java/lang/Object.html#wait-long-), [wait](../../java/lang/Object.html#wait-long-int-)`  
     * ### Methods inherited from class java.io.[OutputStream](../../java/io/OutputStream.html "class in java.io")  
     `[flush](../../java/io/OutputStream.html#flush--), [write](../../java/io/OutputStream.html#write-byte:A-)`

• • Field Detail

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

  • Constructor Detail

    * #### ByteArrayOutputStream  
    public ByteArrayOutputStream​()  
    Creates a new byte array output stream. The buffer capacity is initially 32 bytes, though its size increases if necessary.  
    * #### ByteArrayOutputStream  
    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](../../java/lang/IllegalArgumentException.html "class in java.lang")` \- if size is negative.  

  • Method Detail

    * #### write  
    public void write​(int b)  
    Writes the specified byte to this byte array output stream.  
    Specified by:  
    `[write](../../java/io/OutputStream.html#write-int-)` in class `[OutputStream](../../java/io/OutputStream.html "class in java.io")`  
    Parameters:  
    `b` \- the byte to be written.  
    * #### write  
    public 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.  
    Overrides:  
    `[write](../../java/io/OutputStream.html#write-byte:A-int-int-)` in class `[OutputStream](../../java/io/OutputStream.html "class in java.io")`  
    Parameters:  
    `b` \- the data.  
    `off` \- the start offset in the data.  
    `len` \- the number of bytes to write.  
    * #### writeTo  
    public void writeTo​([OutputStream](../../java/io/OutputStream.html "class in java.io") out)  
                 throws [IOException](../../java/io/IOException.html "class in java.io")  
    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](../../java/io/IOException.html "class in java.io")` \- if an I/O error occurs.  
    * #### reset  
    public 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](../../java/io/ByteArrayInputStream.html#count)  
    * #### toByteArray  
    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:  
    the current contents of this output stream, as a byte array.  
    See Also:  
    [size()](../../java/io/ByteArrayOutputStream.html#size--)  
    * #### size  
    public 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](../../java/io/ByteArrayOutputStream.html#count)  
    * #### toString  
    public [String](../../java/lang/String.html "class in java.lang") 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](../../java/nio/charset/CharsetDecoder.html "class in java.nio.charset") class should be used when more control over the decoding process is required.  
    Overrides:  
    `[toString](../../java/lang/Object.html#toString--)` in class `[Object](../../java/lang/Object.html "class in java.lang")`  
    Returns:  
    String decoded from the buffer's contents.  
    Since:  
    1.1  
    * #### toString  
    public [String](../../java/lang/String.html "class in java.lang") toString​([String](../../java/lang/String.html "class in java.lang") charsetName)  
                    throws [UnsupportedEncodingException](../../java/io/UnsupportedEncodingException.html "class in java.io")  
    Converts the buffer's contents into a string by decoding the bytes using the named [charset](../../java/nio/charset/Charset.html "class in java.nio.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](../../java/nio/charset/CharsetDecoder.html "class in java.nio.charset") class should be used when more control over the decoding process is required.  
    Parameters:  
    `charsetName` \- the name of a supported[charset](../../java/nio/charset/Charset.html "class in java.nio.charset")  
    Returns:  
    String decoded from the buffer's contents.  
    Throws:  
    `[UnsupportedEncodingException](../../java/io/UnsupportedEncodingException.html "class in java.io")` \- If the named charset is not supported  
    Since:  
    1.1  
    * #### toString  
    [@Deprecated](../../java/lang/Deprecated.html "annotation in java.lang")  
    public [String](../../java/lang/String.html "class in java.lang") toString​(int hibyte)  
    Deprecated.  
    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()](../../java/io/ByteArrayOutputStream.html#size--), [toString(String)](../../java/io/ByteArrayOutputStream.html#toString-java.lang.String-), [toString()](../../java/io/ByteArrayOutputStream.html#toString--)  
    * #### close  
    public void close​()  
               throws [IOException](../../java/io/IOException.html "class in java.io")  
    Closing a `ByteArrayOutputStream` has no effect. The methods in this class can be called after the stream has been closed without generating an `IOException`.  
    Specified by:  
    `[close](../../java/lang/AutoCloseable.html#close--)` in interface `[AutoCloseable](../../java/lang/AutoCloseable.html "interface in java.lang")`  
    Specified by:  
    `[close](../../java/io/Closeable.html#close--)` in interface `[Closeable](../../java/io/Closeable.html "interface in java.io")`  
    Overrides:  
    `[close](../../java/io/OutputStream.html#close--)` in class `[OutputStream](../../java/io/OutputStream.html "class in java.io")`  
    Throws:  
    `[IOException](../../java/io/IOException.html "class in java.io")` \- if an I/O error occurs.

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