Assignment #3: Nested Loops, parameters and return values and Scanner Solution

How to hand it in:




Submit files RocketLaunch.java through the Assignment 3 link on the CSC110 conneX site.




Learning Outcomes:




When you have completed this assignment, you should understand:




How to use a nested for loop to repeat a statement a specified number of times.



The effect of escape sequences on printed strings.
More practice with static methods that take parameters and return a value.
Using Scanner to get input from the command line



The flow of control (i.e. the effects of method calls and assignment statements, parameters passed in and return values).



Part 1 – Rocket Launch




Write a set of methods that will output an ascii image as shown above. Your implementation must include the following static method:




/*

PURPOSE:
to
print
a ascii
rocket
ship
of the rocket
INPUT:
int size, controls the proportions
OUTPUT:
int numBoosters,
controls how many
boosters
are drawn
an
ascii
representation
of Apollo Spaceship


*/




public static void drawRocket(int size, int numBoosters)







To receive full marks you must decompose your implementation into multiple methods. That is, your drawRocket method should call other methods to draw the pieces of the rocket. We have not specified what these methods to give you some control over the design of your program.




In your main method you must call your drawRocket method with values collected from the console. For example, here the program is prompting for the size of the rocket and then for the number of boosters. The image on the following page shows the output given this input and the method call: drawRocket(2, 2).

The following is a screenshot of a sample run of drawRocket with a scale size of 2 and 2 boosters. drawRocket(2, 2). The pieces of the spaceship are labeled to give you ideas for deciding what your methods should be. Two more sample runs are provided on the following page.







Part II – Encryption/Decryption




With the release of the movie The Imitation Game, a story Alan Turing’s Life, it seems fitting to think about code breaking. AND every rocket launcher should be able to encrypt/decrypt messages J




You are required to write an encryption and a decryption method as described below.




/*

PURPOSE: encrypts msg given an encryption key between 1 and 95

INPUT: String msg, the message to be encrypted




int key, the amount to increase the ascii character by to encrypt the message




OUTPUT: an encrypted version of msg returned as a String

*/

public static String encrypt(String msg, int key)




/*




PURPOSE: decrypts msg given an encryption key between 1 and 95

INPUT: String msg, the message to be decrypted




int key, the amount to shift the ascii character by to decrypt the message




OUTPUT: a decrypted version of msg returned as a String

*/

public static String decrypt(String msg, int key)







A very basic encryption algorithm is:




message String comes in as a parameter Create a new empty String




For each character in the message String

convert each character to its integer value,

add the encryption key value to the integer value convert the new integer back to a character append the new character to the new String




//end of for loop

Return the new String




A similar, algorithm will work for decryption




message String comes in as a parameter Create a new empty String




For each character in the encrypted message String

convert each character to its integer value,

subtract the encryption key value to the integer value

convert the new integer back to a character

append the new character to the new String Return the new String




The following ASCII table will help you with the conversion of a char to its decimal value. https://www.cs.cmu.edu/~pattis/15-1XX/common/handouts/ascii.html




Your methods must support the conversion of the characters with integer values 32-126 (SPACE character to ~ character).

RECALL: You can cast a character to an integer to get its integer value. Use the table link above to verify the comments in the following example…




char c = ‘a’;
//
c is character a
here
int
x
=
(int) c;
//
x is 97 here
x is now 107
x =
x
+
10;
//
I add 10 to x so
char newC = (char)x;
//newC is the char equivalent of x(107), k



NOTICE: the algorithm above does not take into account when the conversion from a char to an int and the addition of the key results in an integer value out of range.




Ie. The ‘~’ character has an integer value of 126 if I add an encryption key of 5; we get an integer value of 131 which does not have a character value. Your method implementation should account for this.




One suggested solution is provided here for you. There are other ways to do this (use of the mod (%) operator and you may implement it however you chose. This following is just a suggestion.










FINALLY: In your main method you must ask your user if they want to decrypt or encrypt. You will then prompt your user for a message and a key to pass as parameters to the correct method.




This sample run on the following page shows an encryption of “Uptown Funk” with a key of 5 followed by the decryption of this String.




CHALLENGE: Get your implementation to work with a key 95. Hint: the mod operator (%) might be useful.




Grading:




Marks will be allocated for the following…




Your code must compile and run.



Your code should produce the output exactly as requested.
Your code must be indented and documented appropriately. Please follow the guidelines in Style_Guidelines.pdf, available in the Resources folder on conneX.