Java problem: 2d-Arrays

[Piet Souris]

The difference between

public static int makeLastElementEqualToSumOfOtherElements(int[] myArray)

and

public static int[] makeLastElementEqualToSumOfOtherElements(int[] myArray)

is that the first method returns a single int, while the second one returns an array of ints.

If you have a 2D array (in java that is an array of arrays, so where each element is an array itself) you can iterate through the rows as Norm showed you (and that is indeed called an enhanced for-loop)

for (int[] row: my2DArray) {
    // do something with row
}

or using a traditional loop:

for (int i = 0; i < my2DArray.length; i++) {
    // do something with my2DArray[i]
}

My idea to solve your assignment is to have a method say

public (static) int[][] changeLastElementOfAllRows(int[][] my2DArray) {...}

Now, create a 2D array int[][], name it solution, that has my2DArray.length rows. Then, for each row of my2DArray, invoke the method

makeLastElementEqualToSumOfOtherElements(row)

and the array that this method returns will be the corresponding row of the solution. So the method 'changeLastElementOfAllRows' would look something like:

int[][] solution = new int[my2DArray.length][];
for (int index = 0; index < my2DArray.length; index++) {
    solution[index] = ????
}
return solution;

This way, we do not change our 2D input array, but return a completely new 2D array.

Think about it.

[Adebiyi Itunuayo]

Thanks for the clarification sir.

Campbell Ritchie wrote:

Adebiyi Itunuayo wrote:. . . Why is it like that, I mean written with the square brackets together with a method. . . .

Because . . . .

[Adebiyi Itunuayo]

Thank you for this sir. I appreciate your help. I'll post my solution soon.

Piet Souris wrote:The difference between . . .