スパース配列学習の小さなデモ

public class ArrayDemo {
    public static void main(String[] args) {
        int[][] commonArray = new int[11][10];
        commonArray[3][4] = 1;
        commonArray[4][5] = 2;
        for (int[] row : commonArray) {
            for (int value : row) {
                System.out.print(" " + value + " ");
            }
            System.out.println();
        }
        toSparseArray(commonArray);
    }

    private static void toSparseArray(int[][] commonArray) {
        System.out.println("=============拿到一个二维数组开始进行转换");
        if (commonArray != null && commonArray.length != 0){
            int row = commonArray.length;
            if (commonArray[0] != null){
                int col = commonArray[0].length;
                int sum = 0;
                for (int[] commonRow : commonArray) {
                    for (int value : commonRow) {
                        if (value != 0){
                            sum++;
                        }
                    }
                }
                int[][] sparseArray = new int[sum+1][3];
                sparseArray[0][0] = row;
                sparseArray[0][1] = col;
                sparseArray[0][2] = sum;
                int sparseRow = 0;
                sparseRow ++;
                for (int i = 0; i < commonArray.length; i++) {
                    for (int j = 0; j < commonArray[i].length; j++) {
                        if (commonArray[i][j] != 0){
                            sparseArray[sparseRow][0] = i;
                            sparseArray[sparseRow][1] = j;
                            sparseArray[sparseRow][2] = commonArray[i][j];
                            sparseRow ++;
                        }
                    }
                }
                for (int[] newRow1 : sparseArray) {
                    for (int i : newRow1) {
                        System.out.print(" " + i + " ");
                    }
                    System.out.println();
                }
                toReverse(sparseArray);
            }
        }
    }

    private static void toReverse(int[][] array) {
        System.out.println("================从一个稀疏数组还原成普通数组");
        int[][] reArray = new int[array[0][0]][array[0][1]];
        for (int i = 1; i < array.length; i++) {
            reArray[array[i][0]][array[i][1]] = array[i][2];
        }
        for (int[] row : reArray) {
            for (int value : row) {
                System.out.print(" " + value + " ");
            }
            System.out.println();
        }
    }
}