CRC32 (Java SE 22 & JDK 22)
Description: declaration: module: java.base, package: java.util.zip, class: CRC32
Keywords: java.util.zip.CRC32 class

Module java.base
Package java.util.zip

# Class CRC32

java.lang.Object
java.util.zip.CRC32

All Implemented Interfaces:
  `Checksum`

public class CRC32 extends Object implements Checksum
A class that can be used to compute the CRC-32 of a data stream.

Passing a `null` argument to a method in this class will cause a `NullPointerException` to be thrown.

Since:
  1.1

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `CRC32()`
  Creates a new CRC32 object.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `long`
  `getValue()`
  Returns CRC-32 value.
  `void`
  `reset()`
  Resets CRC-32 to initial value.
  `void`
  `update(byte[] b, int off, int len)`
  Updates the CRC-32 checksum with the specified array of bytes.
  `void`
  `update(int b)`
  Updates the CRC-32 checksum with the specified byte (the low eight bits of the argument b).
  `void`
  `update(ByteBuffer buffer)`
  Updates the CRC-32 checksum with the bytes from the specified buffer.

  ### Methods declared in class java.lang.Object

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

  ### Methods declared in interface java.util.zip.Checksum

  `update`

- ## Constructor Details

  - ### CRC32

    public CRC32()
    Creates a new CRC32 object.

- ## Method Details

  - ### update

    public void update(int b)
    Updates the CRC-32 checksum with the specified byte (the low eight bits of the argument b).
    Specified by:
      `update` in interface `Checksum`
    Parameters:
      `b` - the byte to update the checksum with

  - ### update

    public void update(byte[] b, int off, int len)
    Updates the CRC-32 checksum with the specified array of bytes.
    Specified by:
      `update` in interface `Checksum`
    Parameters:
      `b` - the byte array to update the checksum with
      `off` - the start offset of the data
      `len` - the number of bytes to use for the update
    Throws:
      `ArrayIndexOutOfBoundsException` - if `off` is negative, or `len` is negative, or `off+len` is negative or greater than the length of the array `b`.

  - ### update

    public void update(ByteBuffer buffer)
    Updates the CRC-32 checksum with the bytes from the specified buffer. The checksum is updated with the remaining bytes in the buffer, starting at the buffer's position. Upon return, the buffer's position will be updated to its limit; its limit will not have been changed.
    Specified by:
      `update` in interface `Checksum`
    Parameters:
      `buffer` - the ByteBuffer to update the checksum with
    Since:
      1.8

  - ### reset

    public void reset()
    Resets CRC-32 to initial value.
    Specified by:
      `reset` in interface `Checksum`

  - ### getValue

    public long getValue()
    Returns CRC-32 value.
    Specified by:
      `getValue` in interface `Checksum`
    Returns:
      the current checksum value