Module java.base

Package java.util.zip

Interface Checksum

All Known Implementing Classes:

Adler32, CRC32, CRC32C

public interface Checksum

An interface representing a data checksum.

Since:

1.1

Method Summary

Modifier and Type	Method	Description
long	getValue()	Returns the current checksum value.
void	reset()	Resets the checksum to its initial value.
default void	update(byte[] b)	Updates the current checksum with the specified array of bytes.
void	update(byte[] b, int off, int len)	Updates the current checksum with the specified array of bytes.
void	update(int b)	Updates the current checksum with the specified byte.
default void	update(ByteBuffer buffer)	Updates the current checksum with the bytes from the specified buffer.

Method Details

update

void update(int b)

Updates the current checksum with the specified byte.

Parameters:

b - the byte to update the checksum with

update

default void update(byte[] b)

Updates the current checksum with the specified array of bytes.

Implementation Requirements:

This default implementation is equal to calling update(b, 0, b.length).

Parameters:

b - the array of bytes to update the checksum with

Throws:

NullPointerException - if b is null

Since:

9

update

void update(byte[] b,
 int off,
 int len)

Updates the current checksum with the specified array of bytes.

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

update

default void update(ByteBuffer buffer)

Updates the current 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.

API Note:

For best performance with DirectByteBuffer and other ByteBuffer implementations without a backing array implementers of this interface should override this method.

Implementation Requirements:

The default implementation has the following behavior.
For ByteBuffers backed by an accessible byte array.

 update(buffer.array(),
        buffer.position() + buffer.arrayOffset(),
        buffer.remaining());
 

For ByteBuffers not backed by an accessible byte array.

 byte[] b = new byte[Math.min(buffer.remaining(), 4096)];
 while (buffer.hasRemaining()) {
     int length = Math.min(buffer.remaining(), b.length);
     buffer.get(b, 0, length);
     update(b, 0, length);
 }
 

Parameters:

buffer - the ByteBuffer to update the checksum with

Throws:

NullPointerException - if buffer is null

Since:

9

getValue

long getValue()

Returns the current checksum value.

Returns:

the current checksum value

reset

void reset()

Resets the checksum to its initial value.