java将二维数组转成稀疏数组存到map.data文件，读取map.data的稀疏数组转成二维数组

稀疏数组：是一个多行三列的数组，第一行存的是原始数组的行，列，有效值数量；主要是压缩存储空间，例如五子棋完成存盘和续上盘的功能

转成稀疏数组存储就是：

11 11 2

1   2   1

2   3    2

代码实现：

/**
 * @Description 稀疏数组
 * @Author
 * @Date
 **/
public class SparseTest{

    public static void main(String[] args) {
        //初始化原始二维数组
        int[][] num = new int[11][11];
        num[1][2] = 1;
        num[2][3] = 2;

        //将二维数组转成稀疏数组
        //1.计算总共有多少个有效值
        int count = 0;
        for (int[] ints : num) {
            for (int anInt : ints) {
                if(anInt!=0){
                    count++;
                }
            }
        }
        //2.初始化稀疏数组，数组行数=count+1
        int[][] parse = new int[count+1][3];
        //3.给稀疏数组赋值
        parse[0][0] = num.length;
        parse[0][1] = num[0].length;
        parse[0][2] = count;

        int index = 0;
        for(int i=0;i<num.length;i++){
            for(int j=0;j<num[i].length;j++){
                if(num[i][j]!=0){
                    index++;
                    parse[index][0] = i;
                    parse[index][1] = j;
                    parse[index][2] = num[i][j];
                }
            }
        }

        //将稀疏数组存到文件中
        BufferedWriter out;
        {
            try {
                out = new BufferedWriter(new FileWriter("E:\\Java\\test\\map.data"));
                for (int[] ints : parse) {
                    for (int anInt : ints) {
                        out.write(anInt+" ");
                    }
                    out.newLine();
                }
                out.flush();
                out.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        BufferedReader in;
        try {
            in = new BufferedReader(new FileReader("E:\\Java\\test\\map.data"));
            String line = "";
            int rows = 0;
            int cols = 0;
            int sum = 0;
            //读取第一行的值,获得原始数组几行几列，几个有效值
            line = in.readLine();
            String[] strings = line.split(" ");
            rows = Integer.parseInt(strings[0]);
            cols = Integer.parseInt(strings[1]);
            sum = Integer.parseInt(strings[2]);
            //初始化原始数组
            int[][] ori = new int[rows][cols];
            int start = 0;
            while ((line = in.readLine())!=null){
                start++;
                if(start<=sum){
                    String[] split = line.split(" ");
                    ori[Integer.parseInt(split[0])][Integer.parseInt(split[1])] = Integer.parseInt(split[2]);
                }
            }
            for (int[] ints : ori) {
                for (int anInt : ints) {
                    System.out.print(anInt+"\t");
                }
                System.out.println();
            }
            in.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}