mincardinality of properties

if(someClass instanceof MinCardinalityRestriction){
  MinCardinalityRestriction mcr = (MinCardinalityRestriction)someClass;
  int minCard = mcr.getMinCardinality();
}

To check if it's on a certain property

  ...
  //toCheck instanceof Property
  if(mcr.onProperty(toCheck)){
    ...
  }

EDIT: Your code from the comment

//cc1 a class, op a property


if(cc1 instanceof MinCardinalityRestriction){ //check if an owl:Class represented
                                              //by cc1 has a valid
                                              //min-cardinality restriction 
                                              //defined

   MinCardinalityRestriction mcr = (MinCardinalityRestriction)cc1;      
                                              //cast it to an object from 
                                              //which you can
                                              //the cardinality information

   int minCard = mcr.getMinCardinality();     //get the value of the cardinality
                                              //from that object


   if( mcr.onProperty(op)) {                  //check if the cardinality is for 
                                              //the given property op
      System.out.println("minncarrrdinality"); 

   } 
} 

I don't know where to start I'm afraid. To explain what might be going wrong would be to explain Java, and that could take some time. You seem to be tackling three new things at once: Java, OWL and Jena.

I commented the code to try explain what goes on at each line.