Question

Add another method public static void displayObject(ArrayList list, int n) that will display then information on the nth object of list. If n is not a valid index, the method should generate and throw and exception that the main can then process. You get to decide what exception (one built into Java or a custom exception) and how you would like to “handle” the exception (terminate the program, prompt for more input, etc).

Here is the program so far:

import java.util.ArrayList;

public class TestGeometricThing
{
   public static void main (String[] args)
   {
       Square1 s1 = new Square1 (5);
       System.out.println(s1.toString());

       Square1 s2 = new Square1 (3);
       System.out.println(s2.toString());

       ArrayList<GeometricObject> go1 = new ArrayList<GeometricObject>();

       go1.add(new Square1(3));
       go1.add(new Square1(4));
       go1.add(new Square1(5));
       go1.add(new Square1(6));
       go1.add(new Circle(2.0));
       go1.add(new Circle(3.0));
       go1.add(new Circle(4.0));
       go1.add(new Rectangle(2,3));
       go1.add(new Rectangle(3,4));
       go1.add(new Rectangle(4,5));

       System.out.println("Total Area: " + sumArea(go1));
       System.out.println("Biggest Object: " +FindBiggestThing(go1));

   }

   public static double sumArea(ArrayList<GeometricObject>list)
   {
       double totalArea = 0.0;
       for (GeometricObject object:list)
       {
           totalArea += object.getArea();
       }

       return totalArea;

   }

   public static GeometricObject FindBiggestThing(ArrayList<GeometricObject>list)
   {
       GeometricObject biggest = list.get(0);
       for (GeometricObject object:list)
       {
           if (object.getArea() > biggest.getArea())
           {
               biggest = object;
           }
       }

       return biggest;
   }

   public static void displayObject(ArrayList<GeometricObject> list, int n)
   {
   }

}

Answer 1

try this:

public static void displayObject(ArrayList<GeometricObject> list, int n)
{
   if(n< list.size) {
       System.out.print(list.get(n));
   }
   else {
       while(n>= list.size) {
       Scanner scanner = new Scanner(System.in);
       System.out.print("Enter n less than "+n );
       n=scanner.nextInt();
         
   }
}