Java Generic object initialization

Question

Please look at this snippet first :

public MultiThreadManager( Class<T> c) {
    T[] allJobs = (T[]) Array.newInstance( c , MAX_THREAD_SIZE ) ;
    for ( int i = 0 ; i < MAX_THREAD_SIZE ; i ++ ) {
        allJobs[i] = (T) new Object();
        service.submit( allJobs[i] );
        getWaitingThreads().add( allJobs[i] );
    }           
}

Here is the exception :

Exception in thread "main" java.lang.ClassCastException: java.lang.Object cannot be cast to slave.JobTemplate

What I am trying to do :

The Constructor of MultiThreadManager should take a generic type ( say Job.java ) which implements Callable. Create array of all those generic data type ( Job,java ) . Initialize it so the constructor of generic data type ( Job.java ) will run and execute them in a executor service.

Please help me identify my error or please suggest a better way.

Thank You in advance

Thanks you all , but things are little more complex : Herez the other information :

public class Job extends JobTemplate<String> {...details ...}
public abstract class JobTemplate< T > implements Callable<T> {...details..}

and finally

MultiThreadManager< Job > threadManager = new MultiThreadManager< Job >( Job.class );

Again thanks :)

Answer 1

You'll need more reflection, just as you need to create the array:

allJobs[i] = c.newInstance();

and surround with try-catch for all those pesky checked exceptions.

However, I would suggest using new Callable[] because there's no need to go into the specifics of the actual job type. You should also consider a design where reflection is unnecessary: the caller instantiates the jobs instead of passing in the class object. The current solution suffers from the restriction on the Job type to be instantiated only through the default constructor.