Java - Online Test - Oops concepts - javasearch.buggybread.com

Java - Test Questions on 'Oops concepts' - 10 questions found

Which of the following Java feature promotes access protection or Hiding ?

Reference

Core Java

Inheritance

Encapsulation

Abstraction

Composition

_{java java concepts java features oops concepts oops features access protection information hiding}

What is the relationship between Vehicle and Engine in this example ?

public class Vehicle {
   Enginer engine;
   public void move(){
      engine = new Engine();
      engine.start();
   }
}

Core Java

Composition ( Vehicle has a Engine )

Composition ( Engine has a Vehicle )

Inheritance ( Vehicle is a Engine )

Inheritance ( Engine is a Vehicle )

_{composition inheritance oops concepts}

What is the relationship between Car and Vehicle in the following code ?

public class Car extends Vehicle{
   Engine engine;

   public static void main(String[] args){
      Vehicle vehicle = new Car();
      car.move();
   }

   public void move(){
      engine = new Engine();
      engine.start();
   }
}

Core Java

Composition ( Vehicle has a Car )

Composition ( Car has a Vehicle )

Inheritance ( Vehicle is a Car )

Inheritance ( Car is a Vehicle )

_{Inheritance Composition Oops concepts}

What is the problem with the following code ?

public class Car extends Vehicle{
   Vehicle vehicle;

   Car(){
      super();
      this.vehicle = new Vehicle();
   }
}

Core Java

There is an Inheritance as well as Composition relationship between Vehicle and Car which is not permitted

We cannot initialize the parent class instance within the constructor

Call to super is illegal

There is no problem

_{Composition Inheritance OOPS concepts}

Which of the following Java feature promotes Code Re usability ?

Core Java

Abstraction

Encapsulation

Inheritance

Polymorphism