ClassPopularity

package org.scratch.test;

import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Random;
import java.util.concurrent.atomic.AtomicBoolean;

import javax.swing.JFrame;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
import javax.swing.Timer;

import org.scratch.main.util.Pair;
//Pair is a basic utility class that simply stores two fields. Can be implemented in about 50 lines of code if needed, based on Apache Commons Pair.

public class ClassPopularity {
	public static class Results {
		final List<Pair<Integer, Integer>> sample;
		final List<Pair<Integer, Boolean>> thresholds;
		public Results(List<Pair<Integer, Integer>> b, List<Pair<Integer, Boolean>> c) {
			sample = b;
			thresholds = c;
		}
	}
	
	public static Results sample(Random engine, int numOfBuckets, int numOfParticipants, int threshold) {
		List<Pair<Integer, Integer>> results = new ArrayList<>();
		for(int i = 0; i < numOfBuckets; i++) {
			results.add(Pair.of(i, 0));
		}
		for(int i = 0; i < numOfParticipants; i++) {
			int bucket = engine.nextInt(numOfBuckets);
			results.set(bucket, Pair.of(bucket, results.get(bucket).second + 1));
		}
		Collections.sort(results, new Comparator<Pair<Integer, Integer>>() {
			@Override
			public int compare(Pair<Integer, Integer> arg0,
					Pair<Integer, Integer> arg1) {
				return arg1.second - arg0.second;
			}
		});
		List<Pair<Integer, Boolean>> thresholds = new ArrayList<>();
		for(int i = 0; i < numOfBuckets; i++) {
			threshold -= results.get(i).second;
			thresholds.add(Pair.of(i, threshold <= 0));
		}
//		Collections.sort(results, new Comparator<Pair<Integer, Integer>>() {
//			@Override
//			public int compare(Pair<Integer, Integer> arg0,
//					Pair<Integer, Integer> arg1) {
//				return arg0.first - arg1.first;
//			}
//		});
		return new Results(results, thresholds);
	}
	
	public static void main(String[] args) {
		final int NUM_OF_BUCKETS = 12;
		final int NUM_OF_PARTICIPANTS = 30;
		final int THRESHOLD = (int)(NUM_OF_PARTICIPANTS * 0.50);
		JFrame frame = new JFrame("Popularity Graph");
		frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
		JTextArea resultsPanel = new JTextArea(NUM_OF_BUCKETS * 2 + 3, 50);
		resultsPanel.setEditable(false);
		resultsPanel.setFont(new Font("Courier New", Font.PLAIN, 18));
		frame.getContentPane().add(resultsPanel);
		frame.pack();
		frame.setVisible(true);
		frame.setLocationRelativeTo(null);
		frame.setResizable(false);
		final AtomicBoolean running = new AtomicBoolean(true);
		frame.addWindowListener(new WindowAdapter() {
			@Override
			public void windowClosing(WindowEvent arg0) {
				running.set(false);
			}
		});
		final AtomicBoolean shouldPrintResults = new AtomicBoolean(true);
		Timer updateTimer = new Timer(500, new ActionListener() {
			@Override
			public void actionPerformed(ActionEvent arg0) {
				shouldPrintResults.set(true);
			}
		});
		updateTimer.start();

		long numOfTrials = 0;
		long[] numOfSuccesses = new long[NUM_OF_BUCKETS];
		Arrays.fill(numOfSuccesses, 0L);
		Random engine = new Random();
		while(running.get()) {
			Results results = sample(engine, NUM_OF_BUCKETS, NUM_OF_PARTICIPANTS, THRESHOLD);
			numOfTrials++;
			for(Pair<Integer, Boolean> threshold : results.thresholds){
				if(threshold.second)
					numOfSuccesses[threshold.first]++;
			}
			if(shouldPrintResults.get()) {
				shouldPrintResults.set(false);
				setTextArea(resultsPanel, numOfTrials, numOfSuccesses, results, THRESHOLD, NUM_OF_PARTICIPANTS);
			}
		}
		System.out.println("Done.");
		updateTimer.stop();
	}

	private static void setTextArea(final JTextArea resultsPanel, final long numOfTrials, long[] numOfSuccesses, final Results currentResults, final int threshold, final int numOfParticipants) {
		final long[] currentSuccesses = Arrays.copyOf(numOfSuccesses, numOfSuccesses.length);
		SwingUtilities.invokeLater(new Runnable() {
			@Override
			public void run() {
				String text = "";
				text += "Num of Trials:" + String.format("%10d", numOfTrials) + " (PARTICIPANTS=" + numOfParticipants + ")\n";
				text += "Num of Successes (THRESHOLD=" + threshold + "): \n";
				for(int i = 0; i < currentSuccesses.length; i++) {
					text += String.format("    %2d:       %10d (%5.2f%%)\n", i + 1, currentSuccesses[i], (double)currentSuccesses[i] / numOfTrials * 100.0);
				}
				
				text += "Current Results:\n";
				for(Pair<Integer, Integer> ret : currentResults.sample) {
					text += "    " + String.format("%-10s", classNames.get(ret.first)) + ": " + ret.second + "\n";
				}
				text = text.substring(0, text.length() - 1);
				resultsPanel.setText(text);
			}
		});
	}
	
	static Map<Integer, String> classNames = new HashMap<>();
	static {
		classNames.put(0, "Barbarian");
		classNames.put(1, "Bard");
		classNames.put(2, "Cleric");
		classNames.put(3, "Druid");
		classNames.put(4, "Fighter");
		classNames.put(5, "Paladin");
		classNames.put(6, "Rogue");
		classNames.put(7, "Monk");
		classNames.put(8, "Ranger");
		classNames.put(9, "Wizard");
		classNames.put(10, "Warlock");
		classNames.put(11, "Sorcerer");
	}
}