CS46A Spring 19

8A

Complete the class XRectangle. An XRectangle has a x,y location of the upper left hand corner. It represents a rectangle of X's with 4 rows and 5 columns in random colors

You are given a class X which represents a graphical X and that can draw itself at a specified location in a specified color. You can look at its documentation to see the details. Open the X class and select "Documentation" in the upper right drop down menu.

Provide a constructor that takes the x, y coordinates of the upper left hand corner as parameters. Do not draw in the constructor

Provide the method

• draw() which draws 4 rows each containing 5 X objects. Each X is drawn in a random color either red, blue, green or black. You will write and call a getRandomColor method to figure out the color to use. Iterate through the rows in the outer loop and through the columns in the inner loop. That means you will draw the first row, then the second, etc.
• getRandomColor() gets a random color either Color.RED, Color.BLUE, Color.GREEN, Color.BLACK. You are provided with a Random object. Use it and do not change the seed. Generate a random integer 0 to 4 and use the constants defined in the XRectangle class to determine the color. For example if the random number is RED (0) the method will return Color.RED

Other instructions

• Use the constants given in the X class. The numbers 20 and 15 should not appear in your code.
• Use the constants for in the XRectangle class. Don't use 4, 5, etc. The only number in the your statements with be 0.
• You must use nested loops

Your output for the final will look like this.

For the draft, complete the constructor. Implement the draw method to draw the first column all in red. You must use a loop.

8A draft:
8A final:

8B

Write an application CountryList. It will have a main method. In the main method, do the following:

• Create an ArrayList of Strings called countries
• Add "China", "India", "Mexico", "Peru" in that order.
• Add "Spain" at position 1
• Replace the element at index 2 with "Vietnam". You must use the set method
• Replace the next to the last element with "Brazil". Do this in a manner that would replace the next to the last element, no matter the size of the array list. Think about how to find the last element in an array list, then find the index of the next to the last element and use the set method. Don't just use 3 in the set method
• Remove the object "China" Do not remove at an index. Your code should work if "China" was at a different location.

  Note: There is a version of remove method that will remove a specific object. Use that. Do not use the index. Here is the code to remove target from the ArrayList called stuff

  stuff.remove(target);

• Get and print the 0th element followed by "***"
• Print the elements on one line in the [xxx, yyy, ...] format

  Note: To print an ArrayList in the [xxx, yyy, ...] format, use its toString method like this

  System.out.println(stuff.toString());

• Print the entire array list one element to a line (use the enhanced for loop)

Note: You must use an ArrayList and its methods. Do not fake it by just printing the correct strings. You will need to know how to use these methods in a situation where the output can not be faked.

8B draft:
8B final:

8C

Write a class Bookstore which manages Book objects.

The Book class is provided for you. It has a constructor that takes the title of book and its price as parameters. It has methods to getPrice and getTitle. Copy the Book class into your project. Do not change it in any way.

A Bookstore has an instance variable ArrayList<Book>. Call the instance variable books. It has a no-argument constructor (That means it takes no parameters) which initializes the instance variable (the ArrayList of Book objects) to an empty ArrayList.

Provide these methods

• public void add(Book b) which adds the Book to the Bookstore
• public void swap(int index1, int index2) - swaps the element at index1 with the element at index2. If either index is out of bounds, do not changing anything.
• public String cheapest() gets the title for the Book with the lowest price. If more than one Book has the same price, return the title of the first. If the Bookstore object is empty, return the empty string
• public String toString() gets a string representation of the Books in the Bookstore - provided. (This is why the instance variable must be called books.)

Provide Javadoc.

For the draft, define the instance variable and implement the constructor. Also implement the add method.

8C draft:
8C final: