cast

[oll3i]

 public static IBagResult cartesianProduct(IAbstractQueryResult resLeft, 
         IAbstractQueryResult  resRight){
      IBagResult  elements = null;
      List   resLeftL= new ArrayList();
      List   resRightL= new ArrayList();
 
 
     resRightL.add(resRight);
 
     resLeftL.add(resLeft);
 for(int i=0; i<=resLeftL.size(); i++){
 
     for(int j=0; j<= resRightL.size(); j++)
 
     { Integer cP = resLeftL.get(i)*resRightL.get(j);         
 
         elements.addElements(cP);
 
     }   
         }
 return elements;
 
 }

Integer cP = resLeftL.get(i)*resRightL.get(j);

i dont know how to cast it to multiply it

[Nepomuk]

The way I see it, resLeft and resRight (the elements you're adding to the Lists resLeftL and resRightL respectively) aren't numbers so you can't multiply them. What value from them are you trying to multiply?

Also, you should not use raw Lists. Rather than

List resLeftL = new ArrayList();
List resRightL = new ArrayList();

you should use

List<IAbstractQueryResult> resLeftL = new ArrayList<IAbstractQueryResult>();
List<IAbstractQueryResult> resRightL = new ArrayList<IAbstractQueryResult>();

That way the element type returned by resLeftL.get(i) will be known at compile time.

[oll3i]

i want two integers passed as (IAbstractQueryResult resLeft,
IAbstractQueryResult resRigh)
cast them to Integer

where should i cast them

[oll3i]

Exception in thread "main" java.lang.ClassCastException: s4409_s4409_pr2.IntegerResult cannot be cast to java.lang.Integer
at s09_.QExecUtils.cartesianProduct(QExecUtils.java:4 2)
at s09_s4409_pr2.(_pr2.java:38)
Java Result: 1

[oll3i]

how to cast IntegerResult to Integer

[oll3i]

public class IntegerResult implements IIntegerResult{
 Integer i =null;
@Override
public  Integer getValue(){ return i;} 
 
public IntegerResult(Integer i){ 
    this.i=i;
}
 
}

[Nepomuk]

You don't cast it, you call the getValue() function on it. That will return an Integer.