Incompatible type error

[PaulNickel]

Hello everybody,
I have been working on this code segment for about three days and cannot figure out what is causing this error. I am trying to get a specific value out of an arraylist of sorted objects.
Here is the code:

public RateEstimator getMinRate()
    {
        
        
        // return null if array list empty
        
        // first sort the collection via a method call

        // now return the first element in list
        
        // declare a RateEstimator called tmp
        RateEstimator tmp;
        // check for empty array
        if (rates.size() == 0) return null;
        {
            // sort by method call
            sortByRate(); 
            //assign the value in rates position 0 to temp
            tmp = rates.get(0);
            // assign the value of the getRateMethod of temp to
            // a double called smallest
            double smallest = tmp.getTermRate();
            //return the value in smallest
            return smallest;
        }
      
    }

When I try to compile this I get the error : Incompatible types - found double but expected RateEstimator.
RateEstimator is the name of the arrayList I'm working with.

This is in fact part of a homework problem, but I have been through every Java book I own and cannot nail this down. I'm sure I'm missing something simple as I think my basic approch is correct. Any advice would be greatly apriciated.
Thanks
-Paul

[VernonDozier]

Hello everybody,
I have been working on this code segment for about three days and cannot figure out what is causing this error. I am trying to get a specific value out of an arraylist of sorted objects.
Here is the code:

public RateEstimator getMinRate()
    {
        
        
        // return null if array list empty
        
        // first sort the collection via a method call

        // now return the first element in list
        
        // declare a RateEstimator called tmp
        RateEstimator tmp;
        // check for empty array
        if (rates.size() == 0) return null;
        {
            // sort by method call
            sortByRate(); 
            //assign the value in rates position 0 to temp
            tmp = rates.get(0);
            // assign the value of the getRateMethod of temp to
            // a double called smallest
            double smallest = tmp.getTermRate();
            //return the value in smallest
            return smallest;
        }
      
    }

When I try to compile this I get the error : Incompatible types - found double but expected RateEstimator.
RateEstimator is the name of the arrayList I'm working with.

This is in fact part of a homework problem, but I have been through every Java book I own and cannot nail this down. I'm sure I'm missing something simple as I think my basic approch is correct. Any advice would be greatly apriciated.
Thanks
-Paul

Look at lines 1, 22, and 24. Line 1 specifies that this function's return type is RateEstimator. Line 22 specifies that smallest has a type of double. Line 24 says:

return smallest;

Again, smallest is a double and you have declared in line 1 that you are going to return an object of type RateEstimator, not a double. That is your error. You're returning a double, not an object of type RateEstimator, in line 24. So if you want to return a double, change the function to return a double. In that case you'll have to change line 14 so it doesn't return null. If it should return an object of type RateEstimator, you'll need to change line 24.

[PaulNickel]

Thanks for the help, it did indeed correct one problem.
The other problem was that I had written the Junit test wrong.
Now both problems are fixed and that part of my project is working well.
Thanks again.
-Paul