Why is my code causing “unchecked or unsafe operations” warning being flagged by compiler?

Question

My java compiler is complaining that my code uses "unchecked or unsafe operations". Any idea which lines are causing that in the two code snippets?

    @SuppressWarnings("unchecked")
private final void prepareChannelAccountStringsParserImplementedClassConstructor() {
    try {
        String channelAccountStringsParserImplementedClassName = channelIdentifier + "AccountStringsParser";
        Class channelAccountStringsParserImplementedClass = Class.forName(channelAccountStringsParserImplementedClassName);
        Class[] channelAccountStringsParserImplementedClassArguments = new Class[1];
        channelAccountStringsParserImplementedClassArguments[0] = String.class;
        channelAccountStringsParserImplementedClassConstructor = channelAccountStringsParserImplementedClass.getConstructor(channelAccountStringsParserImplementedClassArguments);
        channelAccountStringsParserImplementedParseMethod = channelAccountStringsParserImplementedClass.getMethod("parse", String.class);
        channelAccountStringsParserGetRequestIDMethod = channelAccountStringsParserImplementedClass.getMethod("getRequestID");
    } catch (ClassNotFoundException classNotFoundException) {
        NotifyMeListenersLogsDB notifyMeListenersLogsDB = DatabaseController.getInstance().getNotifyMeListenersLogsDB();
        notifyMeListenersLogsDB.writeDeveloperException(classNotFoundException);
    } catch (NoSuchMethodException noSuchMethodException) {
        NotifyMeListenersLogsDB notifyMeListenersLogsDB = DatabaseController.getInstance().getNotifyMeListenersLogsDB();
        notifyMeListenersLogsDB.writeDeveloperException(noSuchMethodException);
    }
}

    @SuppressWarnings("unchecked")
public synchronized final void requestChannelAccountsCompletionSuccess(String responseContent) {
    Object channelAccountStringsParserImplementedInstance;
    ArrayList<ChannelAccount> channelAccounts = null;
    String requestID = null;
    try {
        channelAccountStringsParserImplementedInstance = channelAccountStringsParserImplementedClassConstructor.newInstance(responseContent);
        channelAccounts = (ArrayList<ChannelAccount>) channelAccountStringsParserImplementedParseMethod.invoke(channelAccountStringsParserImplementedInstance, responseContent);
        requestID = (String) channelAccountStringsParserGetRequestIDMethod.invoke(channelAccountStringsParserImplementedInstance);
    } catch (InstantiationException instantiationException) {
        NotifyMeListenersLogsDB notifyMeListenersLogsDB = DatabaseController.getInstance().getNotifyMeListenersLogsDB();
        notifyMeListenersLogsDB.writeDeveloperException(instantiationException);
    } catch (IllegalAccessException illegalAccessException) {
        NotifyMeListenersLogsDB notifyMeListenersLogsDB = DatabaseController.getInstance().getNotifyMeListenersLogsDB();
        notifyMeListenersLogsDB.writeDeveloperException(illegalAccessException);
    } catch (InvocationTargetException invocationTargetException) {
        NotifyMeListenersLogsDB notifyMeListenersLogsDB = DatabaseController.getInstance().getNotifyMeListenersLogsDB();
        notifyMeListenersLogsDB.writeDeveloperException(invocationTargetException);
    }
    channelAccountStringsParserImplementedInstance = null;
    try {
        startChannelConnections(channelAccounts);
        isStarted = true;
        LoadBalancer.getInstance().sendSuccessAcknowledgement(requestID);
    } catch (NotifyMeListenersApplicationInitializationException notifyMeListenersApplicationInitializationException) {
        NotifyMeListenersLogsDB notifyMeListenersLogsDB = DatabaseController.getInstance().getNotifyMeListenersLogsDB();
        notifyMeListenersLogsDB.writeNotifyMeListenersException(notifyMeListenersApplicationInitializationException);
        System.exit(1);
    }
}

Of course, I put the @SuppressWarnings to suppress it, but I'd like to know the cause. Anyone can help?

Answer 1

Class is a parameterized class. you should use Class<?> (or something more specific if necessary). of course, the compiler error probably tells you exactly where the problem is.

Also, this line is an unchecked cast, but you have no choice on that one:

channelAccounts = (ArrayList<ChannelAccount>)channelAccountStringsParserImplementedParseMethod.invoke(channelAccountStringsParserImplementedInstance, responseContent);