java – Stream from the two-dimensional array in java

To process items only, use flatMap as in Rohit’s answer.

To process elements with their indices, you can use IntStream.range as follows.

import Java.util.stream.IntStream;
import static Java.util.stream.IntStream.range;

public class StackOverflowTest {
    public static void main(String... args) {
        int[][] arr = { { 1, 2, 3 }, { 4, 5, 6 }, { 7, 8, 9 } };
        // Map the two dimensional array with indices.
        final IntStream intStream = range(0, arr.length).flatMap(row -> range(0, arr[row].length).map(col -> {
            final int element = arr[row][col];
            // E.g. multiply elements in odd numbered rows and columns by two.
            return row % 2 == 1 || col % 2 == 1 ? element * 2 : element;
        }));
        // Prints "1 4 3 8 10 12 7 16 9 ".
        intStream.forEachOrdered(n -> System.out.print(n + " "));
    }
}