2D Array population and possible Access Control

[Lost Prophet]

Hi

I have the below code which is to generate a 2D Array... The problem is that I need to populate it by part of array... not by complete array.

For example...
map[1][0] = 1;
map[1][1] = 1;
map[1][2] = 1;

map[3][5] = 2;
map[3][5] = 2;
map[3][5] = 2;

map[6][5] = 3;
map[6][6] = 3;
map[5][5] = 3;

Whenever I am trying to populate the individual element (or any element for that matter), an error is returned saying 'Incompatible types - found int but expected Map'. I know it has something to do with the constructor but I need this as I need the array to be widely available to a number of classes

All the other values can be the default 0 (this would make things easy!). The idea behind it is I need to create a 'map' where the array elements represent a group of individuals and Access Control requests are passed around the determine if the group of individuals can or cannot move to. Essentially its a game like battleships, but more complex

class Map
{
    private Map[][] map;
 
    public Map()
    {
        Map map[][] = new Map[8][10];
    }
 
    public void populateMap(Map[][] map)
    {
        map[1][0] = 1;
    }
 
    public Map getMapData(int x, int y)
    {    
        return map[x][y];  
    }
}

Thanks

[JosAH]

Your 'map' can store 'Map's (note the lower and uppercase) so you can't put an
int in there. Make up your mind of what you want to store in every element of
your two dimensional array.

kind regards,

Jos

[Lost Prophet]

Your 'map' can store 'Map's (note the lower and uppercase) so you can't put an
int in there. Make up your mind of what you want to store in every element of
your two dimensional array.

kind regards,

Jos

All I need in every element is a 1, 2, 3 or 4 so an int but im confused by the above. I used notation from a past example and think that I have got the wrong idea from it

Whenever I try certain things I get different errors so im confused

[JosAH]

All I need in every element is a 1, 2, 3 or 4 so an int but im confused by the above. I used notation from a past example and think that I have got the wrong idea from it

Whenever I try certain things I get different errors so im confused

Why don't you simply make your map an array of ints (or better: bytes) then:

// construct the matrix:
int[][] map= new int[8][10];
...
// put a value in the map:
map[3][4]= 1;
 

Read up on arrays in a tutorial.

kind regards,

Jos

[Lost Prophet]

Why don't you simply make your map an array of ints (or better: bytes) then:

// construct the matrix:
int[][] map= new int[8][10];
...
// put a value in the map:
map[3][4]= 1;
 

Read up on arrays in a tutorial.

kind regards,

Jos

I did this but then the array didnt become available to other methods or classes so thought it would need the constructor or some kind of return value. I'll try again anyway and reply to this if I have any problems with it again

[Lost Prophet]

Two classes below to test the passing of the array from one class to another, its all working but the array in ComplexScript comes out null (so a nullPointerException. This is furthest I have got with it but dont understand why its doing it as I have set the code up in the exact same way that the code was in the workbench that I produced (and that worked). Any pointers?

class ComplexScript
{
    public ComplexScript script;
    public int intMap[][];
 
    public static void main(String args[]) 
    {           
        ComplexScript test = new ComplexScript();
        test.run();
    }
 
    public void run()
    {            
 
        //set up thread for initial explosion
        Runnable initialExplosion = new InitialExplosion(this);
        Thread t1 = new Thread(initialExplosion);
    }
 
    public void print()
    {       
        for (int y = 0;y<10;y++)
        {
            for (int x=0 ; x<8 ; x++)
            {
                //map[x][y]=10*x+y;
                //map[x][y] = 0;
 
                //System.out.print("( "+x+","+y+")  ");
                System.out.print("  " + intMap[x][y] + "   ");
            }
        }      
    }
}

/**
 * Write a description of class array3 here.
 * 
 * @author (your name) 
 * @version (a version number or a date)
 */
public class InitialExplosion implements Runnable
{
    private ComplexScript script;
 
    public InitialExplosion(ComplexScript c)
    {
        script = c;
        run();
    }
 
    public void run()
    {
        populate();   
    }
 
    public void populate()
    {        
        int intMap[][] = new int[8][10];
        //Location of team1
        intMap[0][0] = 1;
        intMap[0][1] = 1;
        intMap[0][2] = 1;
        intMap[1][0] = 1;
        intMap[1][1] = 1;
        intMap[2][0] = 1;
 
        //Location of team2
        intMap[0][7] = 2;
        intMap[0][8] = 2;
        intMap[0][9] = 2;
        intMap[1][8] = 2;
        intMap[1][9] = 2;
        intMap[2][9] = 2;
 
        //Location of team3
        intMap[7][7] = 3;
        intMap[7][8] = 3;
        intMap[7][9] = 3;
        intMap[6][8] = 3;
        intMap[6][9] = 3;
        intMap[5][9] = 3;
 
        //Location of Civilian team
        intMap[5][4] = 4;
        intMap[2][5] = 4;
        intMap[7][4] = 4;
        intMap[7][3] = 4;
        intMap[4][4] = 4;
        intMap[7][0] = 4;
        intMap[3][2] = 4;
 
        script.print();
    }
 
}
 

[JosAH]

When you declare an identifier think of it that you have the remote control
to a television but you haven't got the television yet. You have to explicitly new
the TV set so your remote can control/manipulate it. So:

int[][] map; // you have the remote now
map= new int[8][10]; // and now you have the tv as well.
 

You can shorten this a bit to one step:

int[][] map= new int[8][10]; // a remote and a tv
 

If you don't new a television then all you have is a remote and if you want
to do something with it you get this NullPointerException.

kind regards,

Jos

[Lost Prophet]

Oh sorry. The error was in a different part. I put print statements in other areas and all works fine but in the ComplexScript class the NullPointer is in...

System.out.print("  " + intMap[x][y] + "   ");

Thanks for the help and suggestion though :-D