import java.util.Arrays;

import java.util.Collections;

import java.util.LinkedList;

public class Singleton {

private static Singleton firstInstance = null;

String[] scrabbleLetters = {"a", "a", "a", "a", "a", "a", "a", "a", "a",

"b", "b", "c", "c", "d", "d", "d", "d", "e", "e", "e", "e", "e",

"e", "e", "e", "e", "e", "e", "e", "f", "f", "g", "g", "g", "h",

"h", "i", "i", "i", "i", "i", "i", "i", "i", "i", "j", "k", "l",

"l", "l", "l", "m", "m", "n", "n", "n", "n", "n", "n", "o", "o",

"o", "o", "o", "o", "o", "o", "p", "p", "q", "r", "r", "r", "r",

"r", "r", "s", "s", "s", "s", "t", "t", "t", "t", "t", "t", "u",

"u", "u", "u", "v", "v", "w", "w", "x", "y", "y", "z",};

private LinkedList<String> letterList = new LinkedList<String> (Arrays.asList(scrabbleLetters));

// Used to slow down 1st thread

static boolean firstThread = true;

// Created to keep users from instantiation

// Only Singleton will be able to instantiate this class

private Singleton() { }

// We could make getInstance a synchronized method to force

// every thread to wait its turn. That way only one thread

// can access a method at a time. This can really slow everything

// down though

// public static synchronized Singleton getInstance()

public static Singleton getInstance() {

if(firstInstance == null) {

// This is here to test what happens if threads try

// to create instances of this class

if(firstThread){

firstThread = false;

try {

Thread.currentThread();

Thread.sleep(1000);

} catch (InterruptedException e) {

e.printStackTrace();

}

}

// Here we just use synchronized when the first object

// is created

synchronized(Singleton.class){

if(firstInstance == null) {

// If the instance isn't needed it isn't created

// This is known as lazy instantiation

firstInstance = new Singleton();

// Shuffle the letters in the list

Collections.shuffle(firstInstance.letterList);

}

}

}

// Under either circumstance this returns the instance

return firstInstance;

}

public LinkedList<String> getLetterList(){

return firstInstance.letterList;

}

public LinkedList<String> getTiles(int howManyTiles){

// Tiles to be returned to the user

LinkedList<String> tilesToSend = new LinkedList<String>();

// Cycle through the LinkedList while adding the starting

// Strings to the to be returned LinkedList while deleting

// them from letterList

for(int i = 0; i <= howManyTiles; i++){

tilesToSend.add(firstInstance.letterList.remove(0));

}

// Return the number of letter tiles requested

return tilesToSend;

}

}