Java puzzle 27: Implementing interfaces and casting

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The output of this program is 3200.0, 1199.0. Write only one statement at line 8.
As a result of your statement, the output of this code will be 3100.0, 1350.0
What is that statement?

Java puzzle 27: Implementing interfaces and casting

Level: Hard

public class Test
{
  public static void main(String[] args)
  {
    Payable pay = new Freelancer(3400);
    pay.setTax();
    Freelancer fr = new Freelancer(3500);
    // add your statement here!
    System.out.print(fr.wage + ", ");
    System.out.print(fr.tax);
  }
}
class Freelancer implements Payable
{
  public double wage;
  public double tax = 1234;
  
  public Freelancer(double wage)
  {
    this.wage = wage - 300;
    this.tax -= wage / 100;
  }
  public void setTax()
  {
    this.tax += 150;
  }
}
interface Payable
{
  public void setTax();
}

Author: Sar Maroof

Answer explanation

1. The statement should assign both values 3100.0 and 1350.0 respectively to th variables wage and tax.
2. The reference pay = new Freelancer(3400); assigns the value 3400 – 300 = 3100.0 to the variable wage, and assigns the value (tax = 1234 – 3400/100 = 1200) 1200 to the variable tax. By invoking the method pay.setTax(); the value (this.tax += 150 = 1200 + 150 = 1350) 1350  is assigned to the variable tax.
3. So, the statement is fr = (Freelancer) pay;

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Sar Maroof is graduated from HBO Amsterdam "higher professional education". He is a professional computer programming teacher, gives master classes and publishes technical articles. His experience with developing software started from 2001 and he has worked as a software developer for several big as well as small companies and later as a freelancer. He is the author of Java quizmaster and Build a Java application in 7 days.

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