Assume the existence of a Phone class. Define a subclass, CameraPhone that contains two instance variables: an integer named, imageSize, representing the size in megapixels(for simplicity assume a pixel takes up one byte — thus megapixels equals megabytes) of each picture (i.e., 2 means each image is composed of 2 megapixels), and an integer named memorySize, representing the number of gigabytes in the camera’s memory (i.e., 4 means 4 Gigabyes of memory). There is a constructor that accepts two integer parameters corresponding to the above two instance variables and which are used to initialize the respective instance variables. There is also a method named numPictures that returns (as an integer) the number of pictures the camera’s memory can hold. Don’t forget that a gigabyte is 1,000 megabytes.

LANGUAGE: JAVA

CHALLENGE:

Assume the existence of a Phone class. Define a subclass, CameraPhone that contains two instance variables: an integer named, imageSize, representing the size in megapixels(for simplicity assume a pixel takes up one byte — thus megapixels equals megabytes) of each picture (i.e., 2 means each image is composed of 2 megapixels), and an integer named memorySize, representing the number of gigabytes in the camera’s memory (i.e., 4 means 4 Gigabyes of memory). There is a constructor that accepts two integer parameters corresponding to the above two instance variables and which are used to initialize the respective instance variables. There is also a method named numPictures that returns (as an integer) the number of pictures the camera’s memory can hold. Don’t forget that a gigabyte is 1,000 megabytes.

SOLUTION:

public class CameraPhone extends Phone {
   public CameraPhone(int imageSize, int memorySize) {
      this.imageSize = imageSize;
      this.memorySize = memorySize;
   }

   public int numPictures() {
      return memorySize * 1000 / imageSize;
   }

   private int imageSize;
   private int memorySize;
}

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