Java : CRC32 with Examples
July 22, 2023 
November 9, 2022
CRC32 (Java SE 18 & JDK 18) API Examples.
You will find code examples on most CRC32 methods.
Summary
A class that can be used to compute the CRC-32 of a data stream.
final byte[] b = "abcd".getBytes();
System.out.println(Arrays.toString(b)); // [97, 98, 99, 100]
final var checksum = new CRC32();
checksum.update(b);
System.out.printf("%x%n", checksum.getValue()); // ed82cd11
Constructors
CRC32 ()
Creates a new CRC32 object.
final var checksum = new CRC32();
System.out.printf("%x%n", checksum.getValue()); // 0
checksum.update(123);
System.out.printf("%x%n", checksum.getValue()); // 15d54739
Methods
long getValue ()
Returns CRC-32 value.
final var b = "abcd".getBytes();
System.out.println(Arrays.toString(b)); // [97, 98, 99, 100]
final var checksum = new CRC32();
checksum.update(b);
System.out.printf("%x%n", checksum.getValue()); // ed82cd11
final var checksum = new CRC32();
checksum.update(97);
System.out.printf("%x%n", checksum.getValue()); // e8b7be43
checksum.update(98);
System.out.printf("%x%n", checksum.getValue()); // 9e83486d
checksum.update(99);
System.out.printf("%x%n", checksum.getValue()); // 352441c2
checksum.update(100);
System.out.printf("%x%n", checksum.getValue()); // ed82cd11
void reset ()
Resets CRC-32 to initial value.
final var checksum = new CRC32();
System.out.printf("%x%n", checksum.getValue()); // 0
checksum.update("abcd".getBytes());
System.out.printf("%x%n", checksum.getValue()); // ed82cd11
checksum.reset();
System.out.printf("%x%n", checksum.getValue()); // 0
void update (byte[] b, int off, int len)
Updates the CRC-32 checksum with the specified array of bytes.
final var b = "abcdXYZ".getBytes();
System.out.println(Arrays.toString(b)); // [97, 98, 99, 100, 88, 89, 90]
final var checksum = new CRC32();
checksum.update(b, 0, 4);
System.out.printf("%x%n", checksum.getValue()); // ed82cd11
checksum.reset();
checksum.update(b, 4, 3);
System.out.printf("%x%n", checksum.getValue()); // 7d29f8ed
final var checksum = new CRC32();
checksum.update("abcd".getBytes());
System.out.printf("%x%n", checksum.getValue()); // ed82cd11
checksum.reset();
checksum.update("XYZ".getBytes());
System.out.printf("%x%n", checksum.getValue()); // 7d29f8ed
void update (int b)
Updates the CRC-32 checksum with the specified byte (the low eight bits of the argument b).
Please see getValue().
void update (ByteBuffer buffer)
Updates the CRC-32 checksum with the bytes from the specified buffer.
final var buffer = ByteBuffer.wrap("abcd".getBytes());
System.out.println(buffer); // java.nio.HeapByteBuffer[pos=0 lim=4 cap=4]
final var checksum = new CRC32();
checksum.update(buffer);
System.out.printf("%x%n", checksum.getValue()); // ed82cd11
System.out.println(buffer); // java.nio.HeapByteBuffer[pos=4 lim=4 cap=4]