Question

I have a project and I am facing a problem I had before again.

We have this Tester file given. Should not edit it.
I want you to focus on this line:

System.out.println(bb) ;

It prints the object right?

import java.util.Arrays ;
/**
   Presents some problems to the BillBoard class.
 */
public class BillboardTester
{
    public static void main(String[] args) 
    {
    int[] profits = new int[]{1, 2, 3, 1, 6, 10} ;
    int k = 2 ;
    System.out.println("Profits: " + 
               Arrays.toString(profits) + "   k = " + k)  ;
    Billboard bb = new Billboard(profits, k) ;
    System.out.println("Maximum Profit = " + bb.maximumProfit()) ;
    System.out.println(bb) ;

    k = 3 ;
    profits = new int[]{7, 4, 5, 6, 1, 7, 8, 9, 2, 5} ;
    System.out.println("Profits: " + 
               Arrays.toString(profits) + "   k = " + k)  ;
    bb = new Billboard(profits, k) ;
    System.out.println("Maximum Profit = " + bb.maximumProfit()) ;
    System.out.println(bb) ;
    }
}

Then by printing the object, he expects this result:

Billboards removed (profit): 3(1) 0(1) => profit loss of 2
total value of billboards = 23
remaining maximum profit = 21

I don’t know what method do I have to create in the actual Billboard class, so I can get this printed out. Do you have any suggestions? I want to know the logic behind this, rather than a solution to that particular problem.

Answer 1

Override toString method.

Whenever you print any instance of your class, the toString method is called. If you don’t override it, Object's class toString will be used, which returns a representation having type@someNumber form.

To print your own representation, just override it, and then your implementation of toString will be invoked.

@Override
public String toString() {
    return this.getProfit();
}

You can change your returned string accordingly. I don’t know what your k is, but you can also include that in your returned string.