Lab 5A -- Arrays and Java Swing

This is the first of two new labs to come out this week. In this one, you will get some practice with arrays and Java Swing components, which will help you to prepare for the larger lab assignment that will be due the following week.

You may work alone or with a partner on this lab. Only one submission per group is needed.

To get your BlueJ environment set up for this week's lab assignment, start BlueJ and choose "New Project" from the "Project" menu. Navigate to your folder for this course and choose the name "Lab5A" (no spaces) for the project.

Create a document where you will record your answers to the lecture assignment and lab questions. If you use plain text, call it "lab5A.txt". If it's a Word document, you can call it whatever you'd like, but when you submit, be sure you convert it to a PDF document "lab5A.pdf" before you submit it.

We will usually discuss these questions at the start of class on the lab due date, so no credit can be earned for late submissions of lecture assignment questions.

LA Question 1: Write a method that takes an array of double values as its parameter and returns the sum of all elements in the array. (3 points)

LA Question 2: Write a method that takes an array of String values as its parameter and returns an array of int that contains the lengths of those Strings. That is, each element in the returned array contains the length of the String in the corresponding element of the parameter array. (4 points)

LA Question 3: Gaddis Algorithm Workbench exercise 5, p 532. (3 points)

LA Question 4: The popular Sudoku puzzle game consists of a board that has 9 rows and 9 columns of numbers ranging from 1-9. Suppose we are writing a class to store a Sudoku board. We will assume that filled-in entries contain a number 1 through 9, and blank entries are represented by 0.

Write a declaration of the instance variable board that would store the board using a two-dimensional array of int. Show also the construction of the array. (2 points)
Write a method checkRowValidity that takes a row number (let's use rows numbered 0-8 for simplicity) and checks that no two filled-in entries contain the same number within that row (this would be illegal in the game). It should return true if the row is legal, false if not. (4 points)
Assume you have a similar method checkColValidity (no need to write it). Using your checkRowValidity and checkColValidity methods as building blocks, write a method checkRowsColsValidity that checks that all rows and columns are valid in the current board. (4 points)

Practice Program: Your task is to add some functionality to the Matrix2D example and write code to test it in the main method there. The functionality you are to add:

A method max that returns the largest number in the matrix (4 points)
A destructive method, that is, a method that modifies the matrix on which it is called, named scale that multiplies each entry in the matrix by a number (4 points)
A non-destructive method, that is, one that does not change the matrix on which it is called, named multiply that works much like add but computes the matrix-matrix multiplication result. If you don't remember how to multiply matrices, see the "Matrix Product" section of the Wikipedia entry to Matrix multiplication. (7 points)
Appropriate tests in main (5 points)

Practice Program: Gaddis Programming Challenge 1, p. 448. Write this as a JApplet rather than a GUI application. (5 points)

Before 4:30 PM, Tuesday, June 24, 2014, submit your lab for grading. There are two things you need to do to complete the submission: (i) Copy your file with the answers to the lecture assignment and lab questions into your project directory. Be sure to use the correct file name. If you prepared your answers in Word, export to a PDF file and submit that. (ii) Upload a copy of your lab (a .7z or .zip file containing your project directory) using Submission Box under assignment "Lab5A".

> Feature	Value	Score
Lecture Assignment Quetions	20
`Matrix2D` `max` method	4
`Matrix2D` `scale` method	4
`Matrix2D` `multiply` method	7
`Matrix2D` `main` method enhancements	5
Programming Challenge 1	5
Total	45