Package org.apache.commons.compress.utils

Class BitInputStream

java.lang.Object

org.apache.commons.compress.utils.BitInputStream

All Implemented Interfaces:

Closeable, AutoCloseable

public class BitInputStream
extends Object
implements Closeable

Reads bits from an InputStream.

Since:

1.10

This class is not thread-safe

Constructor Summary

Constructors

Constructor	Description
BitInputStream(InputStream in, ByteOrder byteOrder)	Constructor taking an InputStream and its bit arrangement.

Method Summary

Modifier and Type	Method	Description
void	alignWithByteBoundary()	Drops bits until the next bits will be read from a byte boundary.
long	bitsAvailable()	Returns an estimate of the number of bits that can be read from this input stream without blocking by the next invocation of a method for this input stream.
int	bitsCached()	Returns the number of bits that can be read from this input stream without reading from the underlying input stream at all.
void	clearBitCache()	Clears the cache of bits that have been read from the underlying stream but not yet provided via readBits(int).
void	close()
long	getBytesRead()	Gets the number of bytes read from the underlying stream.
int	readBit()	Reads and returns the next bit read from the underlying stream.
long	readBits(int count)	Reads and returns at most 63 bits read from the underlying stream.

Methods inherited from class java.lang.Object

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

Constructor Details

BitInputStream

public BitInputStream(InputStream in,
 ByteOrder byteOrder)

Constructor taking an InputStream and its bit arrangement.

Parameters:

in - the InputStream

byteOrder - the bit arrangement across byte boundaries, either BIG_ENDIAN (aaaaabbb bb000000) or LITTLE_ENDIAN (bbbaaaaa 000000bb)

Method Details

alignWithByteBoundary

public void alignWithByteBoundary()

Drops bits until the next bits will be read from a byte boundary.

Since:

1.16

bitsAvailable

public long bitsAvailable()
                   throws IOException

Returns an estimate of the number of bits that can be read from this input stream without blocking by the next invocation of a method for this input stream.

Returns:

estimate of the number of bits that can be read without blocking

Throws:

IOException - if the underlying stream throws one when calling available

Since:

1.16

bitsCached

public int bitsCached()

Returns the number of bits that can be read from this input stream without reading from the underlying input stream at all.

Returns:

estimate of the number of bits that can be read without reading from the underlying stream

Since:

1.16

clearBitCache

public void clearBitCache()

Clears the cache of bits that have been read from the underlying stream but not yet provided via readBits(int).

close

public void close()
           throws IOException

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Throws:

IOException

getBytesRead

public long getBytesRead()

Gets the number of bytes read from the underlying stream.

This includes the bytes read to fill the current cache and not read as bits so far.

Returns:

the number of bytes read from the underlying stream

Since:

1.17

readBit

public int readBit()
            throws IOException

Reads and returns the next bit read from the underlying stream.

Returns:

the next bit (0 or 1) or -1 if the end of the stream has been reached

Throws:

IOException - if an I/O error occurs.

Since:

1.28

readBits

public long readBits(int count)
              throws IOException

Reads and returns at most 63 bits read from the underlying stream.

Parameters:

count - the number of bits to read, must be a positive number not bigger than 63.

Returns:

the bits concatenated as a long using the stream's byte order. -1 if the end of the underlying stream has been reached before reading the requested number of bits

Throws:

IOException - if an I/O error occurs.