MySetArray

/**
   MySetArray - array implementation of the MySet interface
*/
public class MySetArray implements MySet{
   //define the data container
   private Object[] set;
   public int cardinality; //holds the count of the actual elements in a set
   private int position; //utility variable

   //constructors
   public MySetArray(int size)         { this.set=new Object[size];}
   public MySetArray()                 { this(10);} //set default set size to ten(10) elements
   //
   public MySetArray(Object[] items)    {
      this.cardinality=items.length;
      this.set=new Object[cardinality];
      for(int i=0;i<cardinality;i++){
         set[i]=items[i];
      }
   }


   //sentinel methods
   public boolean isFull()             { return cardinality==set.length; }
   public boolean isEmpty()            { return cardinality==0;}
   //utility methods
   public boolean isElement(Object item){ //test if an item is in the container
      boolean found=false;
         if(!isEmpty()){
            //use sequential search
            for(int i=0;i<cardinality;i++){
               if(item.equals(set[i])){
                  position=i;
                  found=true;
                  break;
               }
            }
         }
      return found;
   }
   public boolean addElement(Object item){
      boolean ok=!isFull() && !isElement(item);
         if(ok){
            set[cardinality++]=item;
         }
      return ok;
   }
   public boolean deleteElement(Object item){
      boolean ok=isElement(item);
         if(ok){
            // set[position]=set[cardinality-1];
//             set[--cardinality]=null;
            set[position]=set[--cardinality];
         }
      return ok;
   }
   //allowable operations
   public MySet union(MySet parset){
      MySetArray sset=(MySetArray)parset;
      int size=cardinality+sset.cardinality;
      //create a result set
      MySet result=new MySetArray(size);
      //populate the result set, using the current set values
      for(int i=0;i<cardinality;result.addElement(set[i]),i++);
      //populate the result set, using the parameter set values
      java.util.StringTokenizer st=new java.util.StringTokenizer(sset.toString(),"{},");
      for(;st.hasMoreTokens();result.addElement(st.nextToken()));
      // for(;st.hasMoreTokens();){
//          result.addElement(st.nextToken());
//       }
      return result;
   }
   public MySet intersect(MySet parset)   {
      MySetArray sset=(MySetArray)parset;
      int size=(cardinality>sset.cardinality)?cardinality:sset.cardinality;
      MySet result=new MySetArray(size);
         for(int i=0;i<cardinality;i++){
            if(sset.isElement(set[i]))
               result.addElement(set[i]);
         }
      return result;
   }
   public MySet difference(MySet parset)  {
      MySetArray sset=(MySetArray)parset;
      int size=(cardinality>sset.cardinality)?cardinality:sset.cardinality;
      MySet result=new MySetArray(size);
         for(int i=0;i<cardinality;i++){
            if(!sset.isElement(set[i]))
               result.addElement(set[i]);
         }
      return result;
   }
   public MySet crossproduct(MySet parset){
      MySetArray sset=(MySetArray)parset;
      String[] par_array=new String[sset.cardinality];
      //
      int size=cardinality*sset.cardinality;
      MySet result=new MySetArray(size);
      java.util.StringTokenizer st=new java.util.StringTokenizer(sset.toString(),"{},");
      for(int i=0;st.hasMoreTokens();par_array[i++]=st.nextToken());

         for(int i=0;i<cardinality;i++){
            for(int j=0;j<sset.cardinality;j++){
               //temp MySet object with max of 2 elements
               MySetArray temp=new MySetArray(2);
                  temp.addElement(set[i]);
                  temp.addElement(par_array[j]);
                  if(temp.cardinality==2)
                     result.addElement(temp);
            }
         }
      return result;
   }
   //
   public String toString(){
      StringBuffer sb=new StringBuffer();
         sb.append("{");
            for(int i=0;i<cardinality;i++){
               sb.append(set[i]);
               if(i<cardinality-1)
                  sb.append(",");
            }
         sb.append("}");
      return sb.toString();
   }

}//end of class