Another Measurer in Java

Using a different Measurer object, process a set of Rectangle objects to find the rectangle with the largest perimeter.

You need to supply the following class in your solution:
PerimeterMeasurer

Use the following class as your tester class:
import java.awt.Rectangle;

/**
This program tests the measurement of rectangles by perimeter.
*/
public class PerimeterTester
{
public static void main(String[] args)
{
DataSet data = . . .;

data.add(new Rectangle(5, 10, 20, 30));
data.add(new Rectangle(10, 20, 30, 40));
data.add(new Rectangle(20, 30, 5, 10));

double avg = . . .;
Rectangle max = . . .;

System.out.println("Average perimeter: " + avg);
System.out.println("Expected: ");
System.out.println("Largest perimeter: " + max);
System.out.println("Expected: ");
}
}

/**
Computes the average of a set of data values.
*/
public class DataSet
{
private double sum;
private Object maximum;
private int count;
private Measurer measurer;

/**
Constructs an empty data set with a given measurer.
@param aMeasurer the measurer that is used to measure data values
*/
public DataSet(Measurer aMeasurer)
{
sum = 0;
count = 0;
maximum = null;
measurer = aMeasurer;
}

/**
Adds a data value to the data set.
@param x a data value
*/
public void add(Object x)
{
sum = sum + measurer.measure(x);
if (count == 0
|| measurer.measure(maximum) < measurer.measure(x))
maximum = x;
count++;
}

/**
Gets the average of the added data.
@return the average or 0 if no data has been added
*/
public double getAverage()
{
if (count == 0) return 0;
else return sum / count;
}

/**
Gets the largest of the added data.
@return the maximum or 0 if no data has been added
*/
public Object getMaximum()
{
return maximum;
}
}

/**
Describes any class whose objects can measure other objects.
*/
public interface Measurer
{
/**
Computes the measure of an object.
@param anObject the object to be measured
@return the measure
*/
double measure(Object anObject);
}.