Thread: Problems getting value of index in 2D array operation

Before starting to tell the problem with my method, I want to greet everyone in Java community

This time, I have a problem with an 2D array.
Arr is of integer type with dimensions of [4][4].
Let me display the code...

... public static void main(String args[]) { int[][]arr = new int[4][4]; int size=0; for (int i = 0; i < size; i++) { for (int j = 0; j < size; j++) { arr[i][j] = size * j + i; IO.outputln("result is: "+arr[i]+arr[j]); } } }

I would like to know the value stored in arr[1][3] after executing the code above.
I can't see the value in the console. What is missing ?

What result are you getting? Copy and post the console from a sample run.

You've used the 'size' variable before (I think), and you shouldn't be. That's what you're missing in this case. Post your corrected code, and then I'll show you a better way.

Hi Greg.
I can't tell you the result of the operation, because the terminal window doesn't show me anything.
About the variable size, I don't know. I just copied this small line of code from my teacher example to create a better understanding program with an output result ^^

That you're seeing nothing in the terminal window is the result, and it's significant.

Trace the code - keep track of the variable values with pencil and paper if you need to - and determine what will happen at the for loops with size set to 0.

Glad you figured it out. As I said earlier, the code below demonstrates a more appropriate way to write for() loops to iterate arrays.

// a method to demonstrate the declaration and initialization // of a 2D array with 4 rows and 4 columns. the first element of // each row of the array is initialized to the row number, and // each element in the row thereafter increases by one public static void arrayMethod() { // declare a 2D array with 4 rows and 4 columns int[][] arr = new int[4][4];   // initialize the array // for each row, i: arr.length = number of rows for (int i = 0 ; i < arr.length ; i++) { // for each column, j: arr[i].length = the number of // elements or columns in the row i for (int j = 0 ; j < arr[i].length ; j++) { arr[i][j] = j + i; } }   // display the completed array System.out.println( Arrays.deepToString( arr ) );   } // end method arrayMethod()