Comparing values inside a 2D Array in java

Question

I'm working on a question where I need to compare the values inside a 2D Array in java. For example:

int N = 2, c = 2;
int [][] arr = new int[N][c];

System.out.println("Enter the values to a 2D array: ");

for(int i=0; i<N;i++) {
    for (int j=0;j<c;j++) {
        arr[i][j]=in.nextInt();
    }     
}

So in the above code, the user enters the values inside a 2d array. Now I want to compare if arr[i]>=0 and arr[j]>=0 separately and if yes, I need to perform some other operation on this.

But I'm not able to do it that way. Example:

for(int i=0; i<N;i++) {
    for (int j=0;j<c;j++) {
        if (arr[i]>=0 && arr[j]>=0) {
            //Some operation//
        }
    }
}

Kindly suggest me a way to do this operation - comparing the values individually. Thank you.

it is not clear what are you trying to achieve.

John
– John

2015-06-13 11:00:58 +00:00
Commented Jun 13, 2015 at 11:00 — John
– John, Commented Jun 13, 2015 at 11:00

Eran · Accepted Answer · 2015-06-13 10:56:33Z

4

arr1[i] is an array of integers, not an integer, so you can't compare it to an integer. arr1[i][j] is an int, and can be compared to integers.

if (arr[i][j]>=0) is a valid syntax, but it's not clear if that's what you want.

edited Jun 13, 2015 at 10:56

answered Jun 13, 2015 at 10:51

Eran

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2 Comments

sdgd Over a year ago

how do it individually compare there values .. is there any way ?

Eran Over a year ago

@Dev Compare what? An array of integers to 0? What's the meaning of such a comparison? Do you wish to compare each number in the array to 0?

Md. Nasir Uddin Bhuiyan · Accepted Answer · 2015-06-13 11:18:29Z

1

To compare value of a two dimensional array you should go through with each value of that array.

2x2 array

. .

. .

when i=0, j=0

x .

. .

when i=0, j=1

. x

. .

when i=1, j=0

. .

x .

when i=1, j=1

. .

. x

   for(int i=0; i<N;i++) {
      for (int j=0;j<c;j++) {
         if (arr[i][j]>=your_comparable_value ) {
             //Some operation//
         }
      }
   }

answered Jun 13, 2015 at 11:18

Md. Nasir Uddin Bhuiyan

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Comments

VILLAIN bryan · Accepted Answer · 2015-06-13 13:13:03Z

1

You are storing integers in a 2D array. If it helps, you can visually model 2D arrays by thinking of rows and columns - each row and column pair references it's respective storage location in the array. Example:

arr[0][1] = 5; // sets the value of row [0] column [1] to 5

In the second nested 'for' loop (the one you are having some trouble with), you incorrectly referencing the values of your 2D array. Remember, you must specify the pair - arr[int][int] - in which you wish to reference.

if (arr[i]>=0 && arr[j]>=0); //  incorrect way of referencing the desired respective location in the 2D array

Your revised nested 'for' loop with the syntactically accurate 'if' statement:

for(int i=0; i<N; i++)
    for (int j=0; j<c; j++) // side note: consider using final constant(s) replacing variables N and c. In your case, you are explicitly referencing two integers that store the same value - 2
        if (arr[i][j]>=0)
            System.out.println("Array Position [" + i + "][" + j + "] is greater than or equal to 0");

edited Jun 13, 2015 at 13:13

answered Jun 13, 2015 at 11:40

VILLAIN bryan

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2 Comments

Mr Tsjolder from codidact Over a year ago

arr does not expect two integers. arr[i] is a valid array of integers, but can't be compared with 0.

sdgd Over a year ago

thanks for the help. Understood the logic behind it.

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