CODEWITHSUNDEEP
javaarrays2d
Somnath Kadam
Somnath Kadam

Reputation: 6377

How to get 2D subarray from 2D array in JAVA?

Suppose I have 2D array as follow:

int[][] temp={
              {1,2,3,4},
              {5,6,7,8},
              {9,10,11,12}};

and i want to get sub-array start from X direction 1 to 2 and Y direction 1 to 2 i.e. 

{6,7}
{10,11}

can anyone give me solution for above problem.

Upvotes: 10

Views: 17887

Answers (3)

Matt Hyde
Matt Hyde

Reputation: 1650

As an example without using the Arrays class:

int[][] temp = { { 1, 2, 3, 4 }, { 5, 6, 7, 8 }, { 9, 10, 11, 12 } };
int[][] subArray = new int[temp.length][];
for (int i = 0; i < subArray.length; i++) {
    subArray[i] = new int[2];
    subArray[i][0] = temp[i][1];
    subArray[i][1] = temp[i][2];
}

You can then access any part of subArray that you want. This will access the values [[6, 7], [10, 11]]:

for (int x = 1; x < 3; x++) {
    System.out.println(subArray[x][0]);
    System.out.println(subArray[x][1]);
}

[Additional] To address the modified question:

If you want to create a smaller array you can play around with the start and end points of the loop, and the indices accessed within the loop, for example this will create the array you ask for:

int[][] subArray = new int[2][];
for (int i = 1; i < temp.length; i++) {
    subArray[i-1] = new int[2];
    subArray[i-1][0] = temp[i][1];
    subArray[i-1][1] = temp[i][2];
}

Upvotes: 1

Evgeniy Dorofeev
Evgeniy Dorofeev

Reputation: 136062

Here you are

    int[][] temp = { { 1, 2, 3, 4 }, { 5, 6, 7, 8 }, { 9, 10, 11, 12 } };
    int[][] a = new int[temp.length][];
    for (int i = 0; i < temp.length; i++) {
        a[i] = Arrays.copyOfRange(temp[i], 1, 3);
    }
    System.out.println(Arrays.deepToString(a));

output

[[2, 3], [6, 7], [10, 11]]

answering your question in comment if we want to access only [[6, 7], [10, 11]]

    int[][] a = new int[2][];
    for (int i = 1, j = 0; i < 3; i++, j++) {
        a[j] = Arrays.copyOfRange(temp[i], 1, 3);
    }

output

[[6, 7], [10, 11]]

Upvotes: 10

John
John

Reputation: 16007

You could instantiate a new array and loop through the appropriate indices of the original array to initialize the subarray.

Upvotes: 0

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