Java实现二维数组和稀疏数组的相互转换

package datastructure.sparsearray;

import javax.lang.model.element.VariableElement;
import java.io.*;
import java.util.ArrayList;

/**
 * 二维数组<--->稀疏数组
 * 存盘/读盘
 *
 * @author clownadam
 */
public class SparseArray {
    public static void main(String[] args) throws IOException {
        /*创建一个原始的二维数组11*11*/
        int[][] chessArr1 = new int[11][11];
        chessArr1[1][2] = 1;
        chessArr1[2][3] = 2;
        chessArr1[4][5] = 2;
        /*输出原始的二维数组*/
        System.out.println("原始数组--------");
        for (int[] rows : chessArr1) {
            for (int data : rows) {
                System.out.printf("%d", data);
            }
            System.out.println();
        }
        /*将二维数组转成稀疏数组
         * 1.遍历二维数组，得到有效数据(非0数据个数)
         * */
        int sum = 0;
        for (int row = 0; row < chessArr1.length; row++) {
            for (int col = 0; col < chessArr1.length; col++) {
                if (0 != chessArr1[row][col]) {
                    sum++;
                }
            }
        }
        /*将二维数组转成稀疏数组
         * 2.创建对应的稀疏数组
         * */
        int[][] sparseArr = new int[sum + 1][3];
        //给稀疏数组赋值
        sparseArr[0][0] = chessArr1.length;
        sparseArr[0][1] = chessArr1.length;
        sparseArr[0][2] = sum;
        /*用于记录是第几个非0数据*/
        int count = 0;
        //二维数组的非0数据存入稀疏数组
        for (int row = 0; row < chessArr1.length; row++) {
            for (int col = 0; col < chessArr1.length; col++) {
                if (0 != chessArr1[row][col]) {
                    /*chessArr1[row][col]*/
                    count++;
                    sparseArr[count][0] = row;
                    sparseArr[count][1] = col;
                    sparseArr[count][2] = chessArr1[row][col];
                }
            }
        }
        /*输出稀疏数组的*/
        System.out.println();
        System.out.println("稀疏数组--------");
        for (int[] rows : sparseArr) {
            for (int row : rows) {
                System.out.printf("%d\t", row);
            }
            System.out.println();
        }
        /*将稀疏数组写入文件*/
//        writeSparseArrToFile(sparseArr);
//        readSparseArrToFile("sparse.txt");
        /*将稀疏数组恢复成原始的二维数组
         * 1.先读取稀疏数组第一行,根据第一行的数据,创建原始的二维数组
         * */
        int row = sparseArr[0][0];
        int col = sparseArr[0][1];
        int[][] chessArr2 = new int[row][col];
        for (int i = 1; i < sparseArr.length; i++) {
            chessArr2[sparseArr[i][0]][sparseArr[i][1]] = sparseArr[i][2];
        }
        /*输出二维数组*/
        System.out.println("二维数组--------");
        for (int[] rows : chessArr2) {
            for (int data : rows) {
                System.out.printf("%d", data);
            }
            System.out.println();
        }
        /*-------------------读取稀疏数组文件case-----------------------------*/
        int[][] demos = readSparseArrToFile("sparse.txt");
        for (int[] demo : demos) {
            for (int i : demo) {
                System.out.print(i+"\t");
            }
            System.out.println();
        }

    }

    /**
     * 读取文本文件并将其转换为稀疏数组
     * @param fileName 文件名
     * @return 稀疏数组
     * @throws IOException
     */
    private static int[][] readSparseArrToFile(String fileName) throws IOException {
        File sparseFile = new File(fileName);
        FileReader reader = new FileReader(sparseFile);
        BufferedReader br = new BufferedReader(reader);
        String line;
        ArrayList<int[]> list = new ArrayList<>();
        int rows = 0;
        while ((line = br.readLine()) != null) {
            String[] str = line.split("\t");
            if(rows<str.length){
                rows = str.length;
            }
            int[] col = new int[3];
            for (int i = 0; i < str.length; i++) {
                col[i] = Integer.parseInt(str[i]);
                System.out.println(col[i]);
            }
            list.add(col);
        }
        int[][] sparseArr = new int[list.size()][rows];
        for (int i = 0; i < list.size(); i++) {
            for (int j = 0; j < rows; j++) {
                sparseArr[i][j] = list.get(i)[j];
            }
        }
        br.close();
        reader.close();
        return sparseArr;

    }

    /**
     * 实现将稀疏数组写到磁盘文件中
     * @param sparseArr 稀疏数组
     * @throws IOException
     */
    private static void writeSparseArrToFile(int[][] sparseArr) throws IOException {
        File sparseFile = new File("sparse.txt");
        FileWriter writer = new FileWriter(sparseFile);
        BufferedWriter bw = new BufferedWriter(writer);
        for (int[] row : sparseArr) {
            for (int data : row) {
                bw.write(data+"\t");
            }
            bw.write("\n");
            bw.flush();
        }
        bw.close();
        writer.close();
    }
}