How can you convert a 2 dimensional array into a 1 dimensional array in Java

Question

I would like to know how to convert a 2 dimensional array into a 1 dimensional array. I have come up with some code but it doesn\'t exactly seem to work. Can someone please

Answer 1

The length of the 1-dimensional array must be the sums of the lengths of all rows in the 2-dimensional array. Of course, Java doesn't really have "true" 2-dimensional arrays, but arrays of arrays. This code works, and is wrapped in a simple demo program.

public class ArrayFlattening {

public static final String[][] STRINGS2 = {
    {"my", "dog", "has", "fleas"},
    {"how", "now", "brown", "cow"},
    {"short", "row"},
    {"this", "is", "a", "final", "row", "in", "this", "test"},
};

public static String[] flatten(String[][] a2) {
    String[] result = new String[totalSize(a2)];
    int index = 0;
    for (String[] a1 : a2) {
        for (String s : a1) {
            result[index++] = s;
        }
    }
    return result;
}

public static int totalSize(String[][] a2) {
    int result = 0;
    for (String[] a1 : a2) {
        result += a1.length;
    }
    return result;
}

public static void main(String[] args) {
    System.out.println("" + STRINGS2.length + " rows");
    for (String[] strings1 : STRINGS2) {
        System.out.println("" + strings1.length + " strings");
        for (String s : strings1) {
            System.out.print("\t" + s);
        }
        System.out.println();
    }
    String[] strings1 = flatten(STRINGS2);
    System.out.println(strings1.length + " strings");
    for (String s : strings1) {
        System.out.print("\t" + s);
    }
    System.out.println();
}

}