Java/Others/CRC32.java at dev · primary-code-test/Java · GitHub

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package Others;

import java.util.BitSet;

/** Generates a crc32 checksum for a given string or byte array */

public class CRC32 {

public static void main(String[] args) {

System.out.println(Integer.toHexString(crc32("Hello World")));

}

public static int crc32(String str) {

return crc32(str.getBytes());

}

public static int crc32(byte[] data) {

BitSet bitSet = BitSet.valueOf(data);

int crc32 = 0xFFFFFFFF; // initial value

for (int i = 0; i < data.length * 8; i++) {

if (((crc32 >>> 31) & 1) != (bitSet.get(i) ? 1 : 0))

crc32 = (crc32 << 1) ^ 0x04C11DB7; // xor with polynomial

else crc32 = (crc32 << 1);

}

crc32 = Integer.reverse(crc32); // result reflect

return crc32 ^ 0xFFFFFFFF; // final xor value

}