java.util.zip

Class CRC32

java.lang.Object

java.util.zip.CRC32

All Implemented Interfaces:

Checksum

public class CRC32
extends Object
implements Checksum

Computes CRC32 data checksum of a data stream. The actual CRC32 algorithm is described in RFC 1952 (GZIP file format specification version 4.3). Can be used to get the CRC32 over a stream if used with checked input/output streams.

Author:

Per Bothner

See Also:

InflaterInputStream, DeflaterOutputStream

Constructor Summary

Constructors

Constructor and Description
CRC32()

Method Summary

Modifier and Type	Method and Description
long	getValue() Returns the CRC32 data checksum computed so far.
void	reset() Resets the CRC32 data checksum as if no update was ever called.
void	update(byte[] buf) Adds the complete byte array to the data checksum.
void	update(byte[] buf, int off, int len) Adds the byte array to the data checksum.
void	update(int bval) Updates the checksum with the int bval.

Methods inherited from class java.lang.Object

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

Constructor Detail

CRC32

public CRC32()

Method Detail

getValue

public long getValue()

Returns the CRC32 data checksum computed so far.

Specified by:

getValue in interface Checksum

Returns:

the current checksum value

reset

public void reset()

Resets the CRC32 data checksum as if no update was ever called.

Specified by:

reset in interface Checksum

update

public void update(int bval)

Updates the checksum with the int bval.

Specified by:

update in interface Checksum

Parameters:

bval - (the byte is taken as the lower 8 bits of bval)

update

public void update(byte[] buf,
                   int off,
                   int len)

Adds the byte array to the data checksum.

Specified by:

update in interface Checksum

Parameters:

buf - the buffer which contains the data

off - the offset in the buffer where the data starts

len - the length of the data

update

public void update(byte[] buf)

Adds the complete byte array to the data checksum.