BitcoinUtil { public static long convertVarIntByteBufferToLong(ByteBuffer byteBuffer) { byte[] varIntByteArray=convertVarIntByteBufferToByteArray(byteBuffer); return getVarInt(varIntByteArray); } private  BitcoinUtil(); static long convertSignedIntToUnsigned(int signedInt); static byte[] convertIntToByteArray(int intToConvert); static byte[] convertLongToByteArray(long longToConvert); static byte[] convertBigIntegerToByteArray(BigInteger bigIntegerToConvert,int exactArraySize); static byte[] convertVarIntByteBufferToByteArray(ByteBuffer byteBuffer); static long convertVarIntByteBufferToLong(ByteBuffer byteBuffer); static BigInteger getVarIntBI(byte[] varInt); static long getVarInt(byte[] varInt); static byte getVarIntSize(byte firstByteVarInt); static long getSize(byte[] byteSize); static byte[] reverseByteArray(byte[] inputByteArray); static byte[] convertHexStringToByteArray(String hexString); static String convertByteArrayToHexString(byte[] byteArray); static Date convertIntToDate(int dateInt); static boolean compareMagics(byte[] magic1,byte[] magic2); static byte[] getTransactionHash(BitcoinTransaction transaction); static byte[] getTransactionHashSegwit(BitcoinTransaction transaction);  }
@Test public void convertVarIntByteBufferToLong() { ByteBuffer testByteBuffer = ByteBuffer.allocate(1).put(new byte[]{0x01}); testByteBuffer.flip(); long convertedLong = BitcoinUtil.convertVarIntByteBufferToLong(testByteBuffer); assertEquals(1L, convertedLong,"0x01 in ByteBuffer must be 1 as a long"); }