### Question:
PendingTransactionFilter extends Filter<String> { public PendingTransactionFilter(Web3j web3j, Callback<String> callback) { super(web3j, callback); } PendingTransactionFilter(Web3j web3j, Callback<String> callback);   }### Answer:
@Test public void testPendingTransactionFilter() throws Exception { EthLog ethLog = objectMapper.readValue( "{\"jsonrpc\":\"2.0\",\"id\":1,\"result\":[\"0x31c2342b1e0b8ffda1507fbffddf213c4b3c1e819ff6a84b943faabb0ebf2403\",\"0xccc0d2e07c1febcaca0c3341c4e1268204b06fefa4bb0c8c0d693d8e581c82da\"]}", EthLog.class); runTest(ethLog, web3j.ethPendingTransactionHashObservable()); }
@Test public void testPendingTransactionFilter() throws Exception { PlatonLog ethLog = objectMapper.readValue( "{\"jsonrpc\":\"2.0\",\"id\":1,\"result\":[\"0x31c2342b1e0b8ffda1507fbffddf213c4b3c1e819ff6a84b943faabb0ebf2403\",\"0xccc0d2e07c1febcaca0c3341c4e1268204b06fefa4bb0c8c0d693d8e581c82da\"]}", PlatonLog.class); runTest(ethLog, web3j.platonPendingTransactionHashObservable()); }
@Test public void testPendingTransactionFilter() throws Exception { EthLog ethLog = objectMapper.readValue( "{\"jsonrpc\":\"2.0\",\"id\":1,\"result\":[\"0x31c2342b1e0b8ffda1507fbffddf213c4b3c1e819ff6a84b943faabb0ebf2403\",\"0xccc0d2e07c1febcaca0c3341c4e1268204b06fefa4bb0c8c0d693d8e581c82da\"]}", EthLog.class); runTest(ethLog, web3j.ethPendingTransactionHashFlowable()); }