Multidimensional array

[saloni jhanwar]

class Multi 
{
	public static void main(String[] args) 
	{
		int[][] i=new int[3][];
		i[0]=new int[2];
		i[1]=new int[3];
		i[0][0]=1;
		i[0][1]=2;
		i[1][0]=3;
		i[1][1]=4;
		i[1][2]=5;

		for(int[] j:i){
			//Various way to iterate it ??
		}
	}
}

[Greg Brannon]

Two nested for loops that iterate from 0 to < the array.length should work nicely.

[Campbell Ritchie]

There is no such thing as a 2D array. You do realise you are going to hit some nulls when you iterate that array?

[Edwin Torres]

Like they said, initialize the third row (to avoid the null) and use a nested loop:

        for(int[] j:i){
            for (int k=0; k < j.length; k++) {
                System.out.println(j[k]);                     
            }
        }

[Greg Brannon]

Working with arrays of arrays can be confusing, requiring extrapolating simple ideas you probably already know into more complex ones in ways you might not think of or realize are possible. For that reason, I put together a short runnable example that should answer most of your questions. Please ask if you have more.

public class Test5
{
    public static void main(String[] args)
    {
        // define an array of 3 arrays which can be thought of as 3 rows,
        // each of a different number of columns: 2, 3, and 4
        
        // define the number of 'rows' as 3
        int[][] myArray = new int[3][];
        
        // then define the width of each of the rows
        myArray[0] = new int[2];
        myArray[1] = new int[3];
        myArray[2] = new int[4];
        
        // a variable to be used as an array element
        int k = 0;

        for ( int i = 0 ; i < myArray.length ; i++ )
        {
            for ( int j = 0 ; j < myArray[i].length ; j++ )
            {
                // store the element in the array and increment it
                myArray[i][j] = k++;
                
                // print the element at the i, j location
                System.out.println( "Array element [" + i + "][" + j
                        + "] = " + myArray[i][j] );
            }
            
            // add a line feed after each row has printed
            System.out.println();
        }
    }
} 

[Winston Gutkowski]

Edwin Torres wrote:Like they said, initialize the third row (to avoid the null) and use a nested loop:

for(int[] j:i){
   for (int k=0; k < j.length; k++) {...

Or indeed:

for(int[] row : i){
   for (int element : row) {
      System.out.println(element);                     
   }
}

Winston

[saloni jhanwar]

Thanks everyone