Single to multi-dimension array

[Migy]

I read file line by line, which, for example, looks like this:

0 5 6 3
5 9 7 1
2 9 4 3

array dimensions should look line that [line number][element in line]

Here's the code I'm using

        FileReader fr = new FileReader("out.txt"); 
        BufferedReader br2 = new BufferedReader(fr); 
        String line; 
        String[] temp = {};
        String[][] temp2 = {{},{}};
        int line_nr = 0;
        while((line = br2.readLine()) != null)
        { 
        	temp = line.split(" ");
        	for(int i=0; i<=temp.length-1; i++)
        	{
        		temp2[line_nr][i] = temp[i];
        	}
        	line_nr++;
        } 
        fr.close();

But for loop is giving me "java.lang.ArrayIndexOutOfBoundsException: 0" error and I don't see why I should be getting it.
I tried using lots of different approaches, but ended up just wasting my time.

[Petr]

All array is immutable in Java. You need set some size your array or use Collections.

[Migy]

All array is immutable in Java. You need set some size your array or use Collections.

I tested single dimension array without setting it's size and it was working just fine ('n still does), so I decided that same would apply to multiple dimensions =/

Thing is I wouldn't know what size I should set to array, without reading file twice.
If I haven't been told to use array, I wouldn't be using it =D
Just tried to escape using shortest way =D