Question

Build a java program that has Student class, use arrays of objects {name, age, gpa} to saves 3 students records. Use printable interface with abstract print method. Student class inherits from an abstract Person class that has name, age as attributes. It also has the following 2 methods: abstract setAge and concrete setGPA. Below is the hierarchy and a sample run (using netbeans): Hierarchy: Printable Interface print(Object ( ) ): object ] Abstract Person Class Name: String Age: int Abstract setAge(Object ( ) ar, Integer newAge) Concrete setGPA(Object ( ) arr, Double newGPA) Student std 1: Object () std2: Object () std3: Object () Sample Run: Students Records vi: Ahmed 20 3.5 Ali 21 3.7 Islam 19 3.9 Students Records V2: Ahmed 21 3.3

Answer 1

solution:

public abstract class Person {
   // data member
   protected String name;
   protected int age;
   protected double gpa;
  
   // default constructor
   public Person(){
       this.name="";
       this.age=0;
       this.gpa=0;
   }
  
   // default constructor with argument
   public Person(String nm){
       this.name=nm;
       this.age=0;
       this.gpa=0;
   }
  
   // abstract method
   abstract public void setAge(int age);
  
   // concrete method
   public void setGPA(double gpa){
       this.gpa=gpa;
   }
}

/////////////////////////////////////

public interface Printable {
   public void print();
}

/////////////////////////////////////////////

public class Student extends Person implements Printable{

   // constructor
   public Student(){
       // call super class
       super();
   }
  
   public Student(String s){
       // call super constructor
       super(s);
   }
  
   // implement method
   @Override
   public void print() {
       System.out.println(super.name+" "+super.age+" "+super.gpa);
   }

   // override abstract method
   @Override
   public void setAge(int age) {
       super.age=age;
   }

}

////////////////////////////////

public class Driver {
   public static void main(String [] args){
      
       // three array
       String [] name={"Ahmed","Ali","Islam"};
       int [] age={20,21,19};
       double [] gpa={3.5,3.7,3.9};
      
       Student [] students=new Student[3];
      
       // using three array create three student object
       for(int i=0;i<3;i++){
           students[i]=new Student(name[i]);
           students[i].setAge(age[i]);
           students[i].setGPA(gpa[i]);
       }
      
       // print them
       System.out.println("Students Records VI:");
       for(int i=0;i<3;i++){
           students[i].print();      
       }
      
   }
}
/////////////////////////////////////////////

Students Records VI: Ahmed 20 3.5 Ali 21 3.7 Islam 19 3.9

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