### Question:
ECKey implements Serializable { @Nullable public byte[] getPrivKeyBytes() { return bigIntegerToBytes(priv, 32); } ECKey();  ECKey(SecureRandom secureRandom);  ECKey(@Nullable BigInteger priv, ECPoint pub); static ECPoint compressPoint(ECPoint uncompressed); static ECPoint decompressPoint(ECPoint compressed); static ECKey fromPrivate(BigInteger privKey); static ECKey fromPrivate(byte[] privKeyBytes); static ECKey fromPrivateAndPrecalculatedPublic(BigInteger priv, ECPoint pub); static ECKey fromPrivateAndPrecalculatedPublic(byte[] priv, byte[] pub); static ECKey fromPublicOnly(ECPoint pub); static ECKey fromPublicOnly(byte[] pub); ECKey decompress(); boolean isPubKeyOnly(); boolean hasPrivKey(); static byte[] publicKeyFromPrivate(BigInteger privKey, boolean compressed); byte[] getAddress(); byte[] getNodeId(); byte[] getPubKey(); byte[] getPubKey(boolean compressed); ECPoint getPubKeyPoint(); BigInteger getPrivKey(); String toString(); String toStringWithPrivate(); ECDSASignature doSign(byte[] input); ECDSASignature sign(byte[] messageHash); static ECKey signatureToKey(byte[] messageHash, String signatureBase64); byte[] decryptAES(byte[] cipher); static boolean verify(byte[] data, ECDSASignature signature, byte[] pub); boolean verify(byte[] sigHash, ECDSASignature signature); boolean isPubKeyCanonical(); static boolean isPubKeyCanonical(byte[] pubkey); @Nullable static ECKey recoverFromSignature(int recId, ECDSASignature sig, byte[] messageHash, boolean compressed); @Nullable byte[] getPrivKeyBytes(); @Override boolean equals(Object o); @Override int hashCode(); static final ECDomainParameters CURVE; static final BigInteger HALF_CURVE_ORDER; }### Answer:
@Test public void testGetPrivKeyBytes() { ECKey key = new ECKey(); assertNotNull(key.getPrivKeyBytes()); assertEquals(32, key.getPrivKeyBytes().length); }