Create BigInteger from byte array
import java.math.BigInteger; public class Main { public static void main(String[] argv) throws Exception { // A negative value byte[] bytes = new byte[] { (byte) 0xFF, 0x00, 0x00 }; // -65536 // A positive value bytes = new byte[] { 0x1, 0x00, 0x00 }; // 65536 BigInteger bi = new BigInteger(bytes); } }