Return the index of an arbitrary Object in a 2d array java.

Question

I'm trying to find the index of an object placed in an array. The array has been populated like this

for(i = 0 ; i<n ;i++){
    for(j=0; j<n ;j++){
        squares[i][j]= new Square(i,j)
        }

So the array is basically full of Square objects with no name. I want to make a method that returns the index of a square object, like:

getObject(Square s){
{

I've seen other answers calling for the use of

Arrays.asList(array)

And stuff like that, but they all try to return the index for an int or a String.

How should i go about returning the index for any object?

zakinster · Accepted Answer · 2013-04-17 08:12:26Z

1

As long as the comparison operator (equals() method) of your Square is suitable for you, then any of these method would work :

Converting to ArrayList and unsing indexOf and get
Using java.util.Arrays.binarySearch
Do a foreach loop and search manually
etc.

You only need a valid comparison operator, if the default Object.equals()(comparison of object instances) is suitable for your need, then you don't have much to do :

Point getObject(Square s){
{
    for(int i = 0; i<n; i++){
        for(int j = 0; j<n; j++){
            if( squares[i][j].equals(s) ) {
                return Point(i, j);
            }
        }
    }
    return null;
}

Note that if your array is large, it's not the fastest way to do it.

edited Apr 17, 2013 at 8:12

answered Apr 17, 2013 at 8:02

zakinster

10.7k1 gold badge45 silver badges54 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

oko · Accepted Answer · 2013-04-17 08:21:20Z

0

if you can use equals method (assuming n is defined also, or you can use length) :

public int[] getObject(Square s){

int[] returnIndex = new int[2];

for(int i = 0 ; i<this.n ;i++){
    for(int j=0; j<this.n ;j++){ 

        if(s.equals(this.squares[i][j])) {
               returnIndex[0] = i;
               returnIndex[1] = j;
               return returnIndex;
            }

       }
    }
    return null;
}

edited Apr 17, 2013 at 8:21

answered Apr 17, 2013 at 8:13

oko

1,3351 gold badge14 silver badges31 bronze badges

Comments

Sumit · Accepted Answer · 2015-04-29 04:29:45Z

0

i have solved like this

private ArrayList<Square> squareList= new ArrayList<Square>(9);

  for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                mSquare[i][j] = new Square(i, j);
                squareList.add(mSquare[i][j]);
            }
        }

    public int index(int r, int c) {
        return squareList.indexOf(Square(r, c));
    }

answered Apr 29, 2015 at 4:29

Sumit

1,13214 silver badges20 bronze badges

Collectives™ on Stack Overflow

Return the index of an arbitrary Object in a 2d array java.

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related