Part A: Shopping ArrayList
A classic application program is the shopping list: a way of keeping track of which groceries or other items need to be bought, and which of them have already been purchased. Your answer to this question will implement such a shopping list, and simulate a user's changes to the list with data read in from a text file.
First, you will need a class to represent items in the list. Objects of this class will contain two instance variables, a String name of the desired item, and an int quantity that needs to be purchased.
Secondly, you will need two ArrayLists in your program. The first list will keep track of items that still need to be bought (call this the shopping list), and the quantity needed. The second will keep track of the items purchased, and the quantity that has been purchased (call this the purchase list).
The data file used as input to the program will consist of lines containing one of three commands. The first of these is add, which is followed by a quantity and an item name, separated by commas. This will add to the shopping list; if an item with that name already exists, increase the quantity desired by the given number. Otherwise, add a new item to the list with that name and quantity.
The second command is buy, which is also followed by a quantity and an item name. This will add to the purchase list in a similar fashion. Also, if an item with that name is already in the shopping list, reduce the quantity desired by that number. If the quantity of that item reaches zero (or less), remove it from the shopping list. Finally, the list command should print out both lists, showing both the quantity and the item name, one item per line.
Part B: Scatterplot
Write a complete Java program that draws a scatterplot by reading in points of data from a file and displaying them. The input data file consists of a pair of integers representing a point on each line of the file; the first integer is the x coordinate, and the second is the y coordinate of the point. It should then plot a least squares regression line on top of the points.
You may assume that all valid points have x-coordinates in the range [0, 40] and y-coordinates in the range [1, 20]. The least-squares line is calculated using the following formula:
Your program should be able to deal with errors in the data file (by catching NumberFormatException when converting text to integers). Ignore lines containing invalid data or points with coordinates out of range, but do not stop reading the file.
Use a two-dimensional array of characters to store the plot.
Your program should print two scatterplots, using the input files a3plot1.txt and a3plot2.txt.
Attachment:- Assignment.rar