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Thread: Creating multiple arraylists with a loop?

  1. #1
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    Default Creating multiple arraylists with a loop?

    Hi, I am new to this forum and I am in desperate need of help. I am trying to simulate a boggle game with 16 dice. To import the dice, i created a text file of all the letters on all of the dice and created a scanner. I want to create 16 separate arraylists, or "dice", that contain the 6 letters, which are going to be chosen at random, or "rolled", at a later point.

    So far I have got this, and i know it wont work.

    for(int d = 1;d<17;d++){
    	ArrayList<String> dice(d) = new ArrayList<String>();
            for (int i = 0; i < 6; i++){
    		 dice(d).add(in.next());
            }
     }

    So inplace of the (d), i just want the value, or number, of d so in the end ill have dice1, dice2, dice3... etc.

    What are my options?

    please and thx


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    Default Re: Creating multiple arraylists with a loop?

    What you need to do it create a 2D array list.

    ArrayList< ArrayList<String> > dice = new ArrayList< ArrayList<String> >();
    for(int i = 0; i<16; i++){
       ArrayList<String> die = new ArrayList<String>();
       for (int j = 0; j < 6; j++){
           die.add(in.next());
       }
       dice.add(die);
     }

    dice.get(0).get(0); //return face 1 of dice 1

    Although might I add that if you are using fixed sized things, i.e. you will always have 16 dice wth 6 faces, you'd be better of using a 2D array,

    Chris
    chris[at]javaprogrammingforums[dot]com

    Prifysgol Bangor University, North Wales

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    Default Re: Creating multiple arraylists with a loop?

    Thx a bunch. this fixed most of my problems except for one.

    When i try to do "dice.get(int1).get(int2)" Eclipse gives me an error that reads "The method get(int) is undefined for the type Object"

    What do i do?

  4. #4
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    Default Re: Creating multiple arraylists with a loop?

    import java.util.ArrayList;
     
     
    public class Test {
    	public static void main(String[] args) {
    		ArrayList< ArrayList<Character> > dice = new ArrayList< ArrayList<Character> >();
    		for(int i = 0; i<16; i++){
    		   ArrayList<Character> die = new ArrayList<Character>();
    		   for (int j = 0; j < 6; j++){
    		       die.add((char)(Math.random()*17 + 65));
    		   }
    		   dice.add(die);
    		 }
     
     
    		for(int i = 0; i < dice.size(); i++){
    			System.out.print("Dice " + i + ": ");
    			for(int j = 0; j < dice.get(i).size(); j++){
    				System.out.print(dice.get(i).get(j) + " ");
    			}
    			System.out.println();
    		}
    	}
    }
    This works perfectly for me, perhaps you could provide more information about what it is you are doing?

    Chris
    chris[at]javaprogrammingforums[dot]com

    Prifysgol Bangor University, North Wales

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    Default Re: Creating multiple arraylists with a loop?

    Ok so im going to show you all of my code... embarrassing as it may be. I know its not written very well, but im a novice so i guess whatever.

     
    import java.io.*;
    import java.util.*;
     
    public class Boggle {
     
    	public static void main(String[] args){
    		new Boggle();
    	}
     
    	public Boggle(){
    		ArrayList<ArrayList<Character>> dice = new ArrayList<ArrayList<Character>>();
    		// import the cubes
    		importCubes(dice);
     
    		/* THIS CHECKS IF EVERYTHING IS IMPORTED CORRECTLY
    		for(int d = 0; d<dice.size(); d++){
    			for(int l = 0; l<dice.get(d).size(); l++){
    				System.out.print(dice.get(d).get(l) + "\t");
    			}
    			System.out.println();
    		}
    		*/
     
    		// import dictionary
    		// roll the dice
    		Character[][] letterBoard = roll(dice);
    		for(int d = 0; d<letterBoard.length; d++){
    			for(int l = 0; l<letterBoard[d].length; l++){
    				System.out.print(letterBoard[d][l] + "\t");
    			}
    			System.out.println();
    		}
     
    		// find all the possible words
    		// cross check against dictionary
    	}
     
    	public void importCubes(ArrayList x){
     
    		Scanner in = null;
    	    try {
    	      in = new Scanner(new File("Dice.txt"));
    	    }
    	    catch (IOException i)
    	    {
    	      System.out.println("Error: " + i.getMessage());
    	    }
     
    	    for(int i = 0; i<16; i++){
    	    	ArrayList<Character> die = new ArrayList<Character>();
    			for (int j = 0; j < 6; j++){
    				die.add(in.next());
    			}
    			x.add(die);
    	    }
    	}
     
     
    // So the method roll with go through all the 16 spots on the 4x4 grid and pick a random
    // 6 sided dice and put it in that spot, then "roll" it by picking at random one of it's sides and 
    // putting that into Character[][] board.
     
    	public Character[][] roll(ArrayList x){
    		Random rand = new Random();
    		int[] availability = {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1};
    		Character[][] board = null;
    		for(int r = 0;r<4;r++){
    			for(int c = 0;c<4;c++){
    				for(int tries=0;tries<10000;tries++){
    					int d = rand.nextInt(16);
    					if(availability[d]!=0){
    						int l = rand.nextInt(6);
    						board[r][c] =  x.get(d).get(l); // At this line, it underlined the second "get" in 
    						availability[d] = 0;      // red and it suggests to add cast to 'x.get(d)'
    						break;
    					}
    				}
    			}
    		}
     
    		return board;
     
    	}
     
    }

    I am trying to make a Boggle simulator that will be able to randomize(shake) the letters on the 4x4 grid and then find all the words that can be made. I am sure there are MANY things you could fix in this code to be more optimized, but i would like to figure it mostly for myself. Could you please help figure out what is broken?

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