Assignment 1

Java for C programmers

In this assignment you will write a few simple java programs in a procedural (not Object Oriented) style. The purpose of this assignment is to refresh your memory on the Intro to CS course material, and get you up to speed with the basic java syntax.

Task 1: Factorial

Write a program for calculating the factorial function. Your code should reside in a file named Factorial.java. The program will read a number n from the commandline, and will then calculate n! twice, once using a recursive definition, and once using an iterative procedure, and print out the result.

For example, invocation of your program should look like this:

> java Factorial 5
recursive: 120
iterative: 120

(lines starting with > are what you write to the shell, other lines are expected output).

Your main(String[] args) method will read the input number from the args array and convert it from a string to an integer. It will then call the two methods:

public static long factorialIter(long n);
public static long factorialRecursive(long n);

and print the results.

Note: you can convert a string to an integer using the following code:

int n = Integer.parseInt("123");

Task 2: Arrays

Write a program called DescribeNumbers that gets a list of numbers in the commandline, and prints their minimum, maximum, and average values.

> java DescribeNumbers 12 2 3 -9 8
min: -9
max: 12
avg: 3.2

Your program must define and use (at least) the following functions:

public static int[] stringsToInts(String[] numbers);
public static int min(int[] numbers);
public static int max(int[] numbers);
public static float avg(int[] numbers);

Task 3: Sorting

Write a program called Sort that will take a sorting order followed by a list of numbers from the commandline and print out the sorted list of numbers:

> java Sort asc 12 2 3 -9 8 
-9 2 3 8 12
> java Sort desc 12 2 3 -9 8 
12 8 3 2 -9

here, asc means ascending order and desc means descending order.

Note: string comparison is performed using the the .equals() method of String:

String s = "hello";
if (s.equals("hello")) {
   // do something
} 
if (s.equals("goodbye")) {
   // do something else
}

For sorting, you can use the Bubble Sort algorithm.

Submission Instructions

Submit through the Submission System

Please follow the general Submission Instructions for the course.

Make sure your code follows the CodingStyle.

You may ask questions on piazza