For this exercise, you and a partner will profile some monkey simulation software, and improve its performance by refactoring two methods (to be determined by the results of the profiling), as well as writing appropriate pinning tests for each of them. This will consist of several parts:
1. Profiling (before) to determine which methods are the most CPU-intensive
2. Adding at least two pinning tests (in the form of unit tests) to each modified method to show that the functionality is unchanged by your modifications
3. Refactoring the method to be more performant (from a CPU and time perspective)
4. Profiling (after) showing that your rewrite helped make your method more performant
This code runs MonkeySim, which simulates a group of monkeys throwing a banana back around until it gets to the first monkey. It accepts one argument, which states which monkey has the banana initially.
The game shall continue until the first monkey gets the banana, at which point the simulation shall end.
The monkey who has the banana shall throw it to another monkey during each round.
If a monkey is even-numbered (e.g., monkey #2, monkey #4, etc.), then the monkey with the banana shall throw the banana to the monkey equal to one-half of that initial monkey's number. For example, monkey #4 shall throw the banana to monkey #2, and monkey #20 shall throw the banana to monkey #10.
If a monkey is odd-numbered (and not monkey #1), the monkey with the banana shall throw it to the monkey equal to three times the number of that monkey plus one (3n + 1). For example, monkey #5 shall throw the banana to monkey #16 ((3 * 5) + 1).
If Monkey #1 catches the banana, the system shall display the number of rounds it took for Monkey #1 to catch the banana and then the program shall exit.
At each round, the current status of who is doing the throwing and who is catching shall be displayed, along with the round number (which should start at 1). It should use the following format: "Round 1: Threw banana from Monkey (#54 / ID 223546) to Monkey (#27 / ID 223519)"
Each monkey has an ID; this ID shall remain constant. For instance, Monkey #5 shall always have ID 223497, and Monkey #160 shall always have ID 223652. Any changes to the code should not modify the ID value.
Output for a given input should be EXACTLY the same as the initial output. Sample runs are shown in the sample_runs.txt file. Please be sure that your code operates the exact same way as the initial code.
In case of ambiguity in the requirements, the sample_runs.txt file shall be considered the correct implementation.
If you encounter an infinite loop (where, if the algorithm is implemented correctly, the first monkey NEVER gets the banana), you will receive a sizable amount of extra credit, assuming you let me know the initial number you entered.
In order to determine the "hot spots" of the application, you will need to run a profiler such as VisualVM. Using a profiler, determine a method you can use to measurably increase the speed of the application without modifying behavior.
As part of this assignment, you should create "pinning tests". Pinning tests are unit tests which should check that the behavior of a modified method was not changed by your refactor (see the chapter on testing legacy code in AFIST for examples). This program should work EXACTLY the same as before, except it should be faster and take up less CPU time. The only exception is if you come across an error and fix it - no points will be taken off as long as you note it in your email.

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import java.util.*;

public class MonkeySim {

    private static List<Monkey> _monkeyList = new LinkedList<Monkey>();

    public static final int HEADER = 50000;
    * Print out use message and exit with
    * error code 1.

    public static void errorAndExit() {
System.out.println("java MonkeySim <num_monkeys>");
System.out.println("<num_monkeys> must be a positive signed 32-bit integer");

    * Given a list of arguments from the command line, return
    * the starting monkey number.
    * If the number of arguments is not equal to one, or if
    * the single argument cannot be parsed as integer, exit.
    * @param args - array of args from command line
    * @return int - starting monkey
    public static int getStartingMonkeyNum(String[] args) {

int s = 0;

if (args.length != 1) {

try {
    s = Integer.parseInt(args[0]);
} catch (Exception e) {

if (s < 1) {

return s;


    * Get a reference to the first monkey in the list.
    * @return Monkey first monkey in list
    public static Monkey getFirstMonkey(List<Monkey> ml) {

int x = ml.size() - 1;
int f = x * 33;
int r = 17;
int q = f;
for (int j = x; j >= 0; j--) {
    if (ml.get(j).getMonkeyNum() != 1) {
for (int k = 0; k < 50000; k++) {
    q += Math.atan(j) - Math.acos(x) + Math.asin(q);
    } else if (ml.get(j).getMonkeyNum() == 1) {
if (q == 0) {
    r = 4;
return ml.get...

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