Cmsc131 Final Exam Part 1

Front 1

What is meant by the term “algorithm”?

Back 1

A sequence of instructions or steps that can be followed in order to solve a relatively simple well-defined problem. Frequently there are many different known algorithms for solving a problem.

Front 2

Name several problems that can be solved with just an algorithm.

Back 2

Sorting an array of numbers; Finding the quickest route for going to the store; listing the first 1000 prime numbers; factoring an integer into it’s prime factors; combining many baskets of eggs into a single basket using a machine that takes two baskets as input and outputs one basket containing all of the eggs in the first two baskets combined; etc.

Front 3

Name several problems that are too complicated to be solved with just a single algorithm.

Back 3

Running a restaurant; a simulation of a submarine; scheduling the flights for a major airline company; predicting whether or not the economy will improve; etc.

Front 4

What is a “use case”? Imagine that you are working on online banking program. Describe several “use cases” that your program should be able to deal with. (Recall that there are three parts to the description of a “use case”: the pre-conditions, the actions, and the post-conditions.)

Back 4

A use case is a typical scenario that a program may encounter – it describes what factors are involved in the case, how the program handles the case, and what you can assume is true AFTER the program handles the case.

For a “banking program”, a typical “use case” is:

(Withdrawing Money from an ATM)

Pre-conditions: Customer has an account with money in it and has a valid ATM card; ATM has money in it; ATM has paper in order to print receipts.

Actions: Customer puts card into machine; ATM reads card; Customer enters withdrawal transaction; ATM spits out money; ATM spits out receipt; ATM spits out card

Post-conditions: Customer has more money; ATM has less money and less paper

Front 5

If you are working on a Java project outside of eclipse, what command would you type to compile a file called “Fish.java”?

Back 5

Javac Fish.java

Front 6

.If you are working on a Java project outside of eclipse, what command would you type to run the main method of a bytecode file called “Fish.class”?

Back 6

Java Fish

Front 7

What is the purpose of the parameter “args” in the prototype for the standard main method?

Back 7

It allows data to be passed to the program at the moment the program is executed.

Front 8

What style of comments do you use to the right of a statement?

Back 8

// This is a comment

Front 9

What style of comments do you use to describe a group of several statements?

Back 9

/* This is usually used for a block */

Front 10

What style of comments do you use to document your API?

Back 10

/** This is a javadoc comment */

Front 11

If you are writing Javadoc for a class, what information should you include? What should you leave out?

Back 11

A basic description of the class. You leave out a lot of small details that will be described in the documentation for the methods.

Front 12

If you are writing Javadoc for a method, what information should you include? What should you leave out?

Back 12

The javadoc should contain everything that the USER of the method needs to know. This includes pre-conditions and post-conditions, as well as a description of things that may go wrong. Frequently details of HOW the method works are left out, but are described in a non-javadoc style comment.

Front 13

Who is going to see your Javadoc comments? (Hint: there are two very different audiences.)

Back 13

The “user” of the class. (Another programmer who will be using this class in his/her project.)

Also anyone who inspects your code.

Front 14

.Who is going to see your internal comments (not Javadoc?) (Hint: just one audience.)

Back 14

Someone who is inspecting your code.

Front 15

Which type of comments should be used for members that are “public”?

Back 15

Always use javadoc; sometimes also use a non-javadoc comment for things that do not need to be mentioned in the API description.

Front 16

Which type of comments should be used for members that are “private”?

Back 16

Javadoc is not necessary here, just use non-javadoc comments to describe how the method works.

Front 17

Does it ever make sense for an internal (non-Javadoc) comment to duplicate the code?

Back 17

No.

Front 18

Does it ever make sense for a Javadoc comment to duplicate the code?

Back 18

Yes, since the “user” of the class typically does not get to see the code.

Front 19

What is the format of the document that the Javadoc utility creates?

Back 19

HTML

Front 20

True/False: A java source-code file can contain more than one class.

Back 20

True

Front 21

True/False: A java source-code file can contain more than one public class.

Back 21

False

Front 22

When you use a public class inside of it’s own package do you need to use a fully qualified name?

Back 22

No

Front 23

Can you use a public class outside of it’s package? Do you need to use a fully qualified name?

Back 23

Yes, and you MUST use the fully qualified name.

Front 24

When you use a non-public class (with no visibility specified) inside of it’s own package, do you need to use a fully qualified name?

Back 24

No.

Front 25

Can you use a non-public class (with no visibility specified) outside of it’s package?

Back 25

No.

Front 26

If you write a class without specifying a particular package, which package will it become part of?

Back 26

Default Package

Front 27

What syntax would you use at the top of a source-code file to specify that the class belongs in a subpackage called “stuff” that is part of a larger package called “junk”?

Back 27

package junk.stuff;