Question

Suppose we have the following Java Interface:

public interface Measurable {   

double getMeasure(); // An abstract method   

static double average(Measurable[] objects) { // A static method   

double sum = 0;   

for (Measurable obj : objects) {   

sum = sum + obj.getMeasure();   

}   
if (objects.length > 0) { return sum / objects.length; }   

else { return 0; }   
}
}
Write a class, called Person, that has two instance variables, name (as String) and age (as double), that implements Measurable interface. Implement required method from the Measurable interface, such that it returns the age of the person.
Then complete the following tester class:
public class MeasurableTester {   

public static void main(String[] args) {   

// Calling the static average method with an array of Person objects   

Measurable[] persons = new ____________[3];   

persons[0] = new _________(10);   

persons[1] = new _________(25);   

persons[2] = new _________(13);   

double averageAge = _____________________________;   

System.out.println("Average ages: " + ______________); }

}

Answer 1

//Measurable.java
public interface Measurable {

  double getMeasure(); // An abstract method
  static double average(Measurable[] objects) { // A static method

    double sum = 0;

    for (Measurable obj : objects) {

      sum = sum + obj.getMeasure();

    }
    if (objects.length > 0) { return sum / objects.length; }

    else { return 0; }
  }
}

==========================================

//Person.java
public class Person implements Measurable {
  String name;
  public double age;

  public Person(double age) {
    this.age = age;
  }


  public double getMeasure() {
    return age;
  }
}

=====================================

//MeasurableTester.java
public class MeasurableTester {

  public static void main(String[] args) {

// Calling the static average method with an array of Person objects

    Measurable[] persons = new Person[3];

    persons[0] = new Person(10);

    persons[1] = new Person(25);

    persons[2] = new Person(13);

    double averageAge = Measurable.average(persons);

    System.out.println("Average ages: " + averageAge);
  }

}

Average ages: 16.0