Question

Task at hand:Consider a class ratingScore that represents a numeric rating for some thing such as a move. Attributes: A description of what is being rated, The maximum possible rating, rating.

It will have methods to: get rating from ta user, Return the maximum rating posisble, return the rating, return a string showing the rating in a format suitable for display.

a. write a method heading for each method
b. write pre and post conditions for each method
c. write some java statements to test the class
d. implement the class.

I think i did what i was supposed to do, but it is a method and i am not sure that i put enough room for it to be changed much, this is what i have so far.

import java.util.*;
public class MovieRating 
{
    // instance variables
    private String description = " A movie that shows how racism affect our lives and choices";
    private int maxRating = 10;
    private int rating;

    // methods 

    //precondition: Must have maxRating, rating and description before you post it back to the user.
    //rating between 1 and 10, maxRating is set to 10, description of a movie
    public void writeOutput()
    {
        System.out.println("The max rating is: " + maxRating );
        System.out.println("Your rating is: " + rating );

        System.out.println("The rating for" + description + " is " + rating); 
        System.out.println("while the max rating was " + maxRating);
    }

    // PostCondition: Will write maxRating, rating and description to the user.

    //Precondition: description, enter the rating
    public void readInput()
    {
        Scanner keyboard = new Scanner(System.in);
        System.out.println("What would you rate the movie \"American History x\" out of ten");
        System.out.println(description);
        rating = keyboard.nextInt();
    }
    //postcondition: rating will be set to user's input for the movie American History x.



}

This is my Tester program.. not much so far

public class MovieRatingTester 
{
    public static void main(String[] args)
    {

        //object of the class MovieRating
        MovieRating rating1 = new MovieRating();

        rating1.readInput();

        rating1.writeOutput();

    }

}

SO did i cover what was told to cover? i think i did but i think i did it the wrong way, let me know please.

Answer 1

Ok, my point of view is:

Your class, MovieRating is missing some basic elements of OOP, and that is what I think you suppose to learn in this homework.

The first element missing is a constructor method, what you did is automatically assigning each new MovieRating the same description. The job of the constructor function is giving a unique values to the Object when it first built in the system.

The constructor method is special, it is public and has the exact same name is the class, as we said, in this method you suppose to assign values to your object variables.

the second thing will be to put getters/setters, these are methods who has access to your private values and will be used to assign/get the values from them. Note the use of them in the code:

import java.util.*;
public class MovieRating 
{

// instance variables
private String description;
private int maxRating;
private int rating;

/*This is the constructor
  Note the use of .this - the expression is used to call the class form withing  
  itself*/
public MovieRating(String description, int maxRating, int rating) {
    this.setDescription(description);
    this.setMaxRating(maxRating);
    this.setRating(rating);
}

/*These are the getters and setters - get is used for getting the value
  and set is used for assigning a value to it*/
public String getDescription() {
    return description;
}

public void setDescription(String description) {
    this.description = description;
}

public int getMaxRating() {
    return maxRating;
}

public void setMaxRating(int maxRating) {
    this.maxRating = maxRating;
}

public int getRating() {
    return rating;
}

public void setRating(int rating) {
    this.rating = rating;
}

//This is a method for the printing commands - notice the use of the get methods//
public void printRatings()
{
    System.out.println("The max rating is: " + this.getMaxRating() );
    System.out.println("Your rating is: " + this.getRating() );

    System.out.println("The rating for" + this.getDescription() + " is " + 
                        this.getRating()); 
    System.out.println("while the max rating was " + this.getMaxRating();
    }

// PostCondition: Will write maxRating, rating and description to the user.

/*Precondition: description, enter the rating
  Note the use of this.setRating()*/
public void readInput()
{
    Scanner keyboard = new Scanner(System.in);
    System.out.println("What would you rate the movie \"American History x\" out of ten");
    System.out.println(description);
    this.setRating(keyboard.nextInt());
}
//postcondition: rating will be set to user's input for the movie American History x.

}

Using the constructor, you can create a different rating from your tester program

MovieRating rating1 = new MovieRating("description 1", 10, 5);
MovieRating rating2 = new MovieRating("description 2", 9, 7);