Module java.base

Package java.io

Class ByteArrayInputStream

java.lang.Object

java.io.InputStream

java.io.ByteArrayInputStream

All Implemented Interfaces:

Closeable, AutoCloseable

public class ByteArrayInputStream
extends InputStream

A ByteArrayInputStream contains an internal buffer that contains bytes that may be read from the stream. An internal counter keeps track of the next byte to be supplied by the read method.

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

Since:

1.0

See Also:

• StringBufferInputStream

Field Summary

Fields

Modifier and Type	Field	Description
protected byte[]	buf	An array of bytes that was provided by the creator of the stream.
protected int	count	The index one greater than the last valid character in the input stream buffer.
protected int	mark	The currently marked position in the stream.
protected int	pos	The index of the next character to read from the input stream buffer.

Constructor Summary

Constructors

Constructor	Description
ByteArrayInputStream(byte[] buf)	Creates a ByteArrayInputStream so that it uses buf as its buffer array.
ByteArrayInputStream(byte[] buf, int offset, int length)	Creates ByteArrayInputStream that uses buf as its buffer array.

Method Summary

Modifier and Type	Method	Description
int	available()	Returns the number of remaining bytes that can be read (or skipped over) from this input stream.
void	close()	Closing a ByteArrayInputStream has no effect.
void	mark(int readAheadLimit)	Set the current marked position in the stream.
boolean	markSupported()	Tests if this InputStream supports mark/reset.
int	read()	Reads the next byte of data from this input stream.
int	read(byte[] b, int off, int len)	Reads up to len bytes of data into an array of bytes from this input stream.
byte[]	readAllBytes()	Reads all remaining bytes from the input stream.
int	readNBytes(byte[] b, int off, int len)	Reads the requested number of bytes from the input stream into the given byte array.
void	reset()	Resets the buffer to the marked position.
long	skip(long n)	Skips n bytes of input from this input stream.

Methods declared in class java.io.InputStream

nullInputStream, read, readNBytes, skipNBytes, transferTo

Methods declared in class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

buf

protected byte[] buf

An array of bytes that was provided by the creator of the stream. Elements buf[0] through buf[count-1] are the only bytes that can ever be read from the stream; element buf[pos] is the next byte to be read.

pos

protected int pos

The index of the next character to read from the input stream buffer. This value should always be nonnegative and not larger than the value of count. The next byte to be read from the input stream buffer will be buf[pos].

mark

protected int mark

The currently marked position in the stream. ByteArrayInputStream objects are marked at position zero by default when constructed. They may be marked at another position within the buffer by the mark() method. The current buffer position is set to this point by the reset() method.

If no mark has been set, then the value of mark is the offset passed to the constructor (or 0 if the offset was not supplied).

Since:

1.1

count

protected int count

The index one greater than the last valid character in the input stream buffer. This value should always be nonnegative and not larger than the length of buf. It is one greater than the position of the last byte within buf that can ever be read from the input stream buffer.

Constructor Details

ByteArrayInputStream

public ByteArrayInputStream(byte[] buf)

Creates a ByteArrayInputStream so that it uses buf as its buffer array. The buffer array is not copied. The initial value of pos is 0 and the initial value of count is the length of buf.

Parameters:

buf - the input buffer.

ByteArrayInputStream

public ByteArrayInputStream(byte[] buf,
 int offset,
 int length)

Creates ByteArrayInputStream that uses buf as its buffer array. The initial value of pos is offset and the initial value of count is the minimum of offset+length and buf.length. The buffer array is not copied. The buffer's mark is set to the specified offset.

Parameters:

buf - the input buffer.

offset - the offset in the buffer of the first byte to read.

length - the maximum number of bytes to read from the buffer.

Method Details

read

public int read()

Reads the next byte of data from this input stream. The value byte is returned as an int in the range 0 to 255. If no byte is available because the end of the stream has been reached, the value -1 is returned.

This read method cannot block.

Specified by:

read in class InputStream

Returns:

the next byte of data, or -1 if the end of the stream has been reached.

read

public int read(byte[] b,
 int off,
 int len)

Reads up to len bytes of data into an array of bytes from this input stream. If pos equals count, then -1 is returned to indicate end of file. Otherwise, the number k of bytes read is equal to the smaller of len and count-pos. If k is positive, then bytes buf[pos] through buf[pos+k-1] are copied into b[off] through b[off+k-1] in the manner performed by System.arraycopy. The value k is added into pos and k is returned.

Unlike the overridden method of InputStream, this method returns -1 instead of zero if the end of the stream has been reached and len == 0.

This read method cannot block.

Overrides:

read in class InputStream

Parameters:

b - the buffer into which the data is read.

off - the start offset in the destination array b

len - the maximum number of bytes read.

Returns:

the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.

Throws:

NullPointerException - If b is null.

IndexOutOfBoundsException - If off is negative, len is negative, or len is greater than b.length - off

See Also:

• InputStream.read()

readAllBytes

public byte[] readAllBytes()

Description copied from class: InputStream

Reads all remaining bytes from the input stream. This method blocks until all remaining bytes have been read and end of stream is detected, or an exception is thrown. This method does not close the input stream.

When this stream reaches end of stream, further invocations of this method will return an empty byte array.

Note that this method is intended for simple cases where it is convenient to read all bytes into a byte array. It is not intended for reading input streams with large amounts of data.

The behavior for the case where the input stream is asynchronously closed, or the thread interrupted during the read, is highly input stream specific, and therefore not specified.

If an I/O error occurs reading from the input stream, then it may do so after some, but not all, bytes have been read. Consequently the input stream may not be at end of stream and may be in an inconsistent state. It is strongly recommended that the stream be promptly closed if an I/O error occurs.

Overrides:

readAllBytes in class InputStream

Returns:

a byte array containing the bytes read from this input stream

readNBytes

public int readNBytes(byte[] b,
 int off,
 int len)

Description copied from class: InputStream

Reads the requested number of bytes from the input stream into the given byte array. This method blocks until len bytes of input data have been read, end of stream is detected, or an exception is thrown. The number of bytes actually read, possibly zero, is returned. This method does not close the input stream.

In the case where end of stream is reached before len bytes have been read, then the actual number of bytes read will be returned. When this stream reaches end of stream, further invocations of this method will return zero.

If len is zero, then no bytes are read and 0 is returned; otherwise, there is an attempt to read up to len bytes.

The first byte read is stored into element b[off], the next one in to b[off+1], and so on. The number of bytes read is, at most, equal to len. Let k be the number of bytes actually read; these bytes will be stored in elements b[off] through b[off+k-1], leaving elements b[off+k ] through b[off+len-1] unaffected.

The behavior for the case where the input stream is asynchronously closed, or the thread interrupted during the read, is highly input stream specific, and therefore not specified.

If an I/O error occurs reading from the input stream, then it may do so after some, but not all, bytes of b have been updated with data from the input stream. Consequently the input stream and b may be in an inconsistent state. It is strongly recommended that the stream be promptly closed if an I/O error occurs.

Overrides:

readNBytes in class InputStream

Parameters:

b - the byte array into which the data is read

off - the start offset in b at which the data is written

len - the maximum number of bytes to read

Returns:

the actual number of bytes read into the buffer

skip

public long skip(long n)

Skips n bytes of input from this input stream. Fewer bytes might be skipped if the end of the input stream is reached. The actual number k of bytes to be skipped is equal to the smaller of n and count-pos. The value k is added into pos and k is returned.

Overrides:

skip in class InputStream

Parameters:

n - the number of bytes to be skipped.

Returns:

the actual number of bytes skipped.

See Also:

• InputStream.skipNBytes(long)

available

public int available()

Returns the number of remaining bytes that can be read (or skipped over) from this input stream.

The value returned is count - pos, which is the number of bytes remaining to be read from the input buffer.

Overrides:

available in class InputStream

Returns:

the number of remaining bytes that can be read (or skipped over) from this input stream without blocking.

markSupported

public boolean markSupported()

Tests if this InputStream supports mark/reset. The markSupported method of ByteArrayInputStream always returns true.

Overrides:

markSupported in class InputStream

Returns:

true if this stream instance supports the mark and reset methods; false otherwise.

Since:

1.1

See Also:

• InputStream.mark(int)
• InputStream.reset()

mark

public void mark(int readAheadLimit)

Set the current marked position in the stream. ByteArrayInputStream objects are marked at position zero by default when constructed. They may be marked at another position within the buffer by this method.

If no mark has been set, then the value of the mark is the offset passed to the constructor (or 0 if the offset was not supplied).

Note: The readAheadLimit for this class has no meaning.

Overrides:

mark in class InputStream

Parameters:

readAheadLimit - the maximum limit of bytes that can be read before the mark position becomes invalid.

Since:

1.1

See Also:

• InputStream.reset()

reset

public void reset()

Resets the buffer to the marked position. The marked position is 0 unless another position was marked or an offset was specified in the constructor.

Overrides:

reset in class InputStream

See Also:

• InputStream.mark(int)
• IOException

close

public void close()
           throws IOException

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

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Overrides:

close in class InputStream

Throws:

IOException - if an I/O error occurs.