思路：
1、遍历原始数组，得到有效数据个数count；
2、根据第一步得到的数据新建稀疏数组arry[count][3];
3、将有效数据存入稀疏数组
//二维数组转稀疏数组
public static int[][] TwoDimensionalToSparseMartix(int[][] TwoDimensionalArray) {
int[][] TDA = TwoDimensionalArray;
int count = 0;
//循环内遍历得到二维数组内的有效值个数
//用来新建数组时候，确定数组行数
for (int i = 0; i < TDA.length; i++) {
for (int j = 0; j < TDA[0].length; j++) {
if (TDA[i][j] != 0) {
count++;
}
}
}
int[][] SAM = new int[count + 1][3];
SAM[0][0] = TDA.length;
SAM[0][1] = TDA[0].length;
SAM[0][2] = count;
int flag = 0;
//循环赋值
for (int i = 0; i < TDA.length; i++) {
for (int j = 0; j < TDA[0].length; j++) {
if (TDA[i][j] != 0) {
SAM[++flag][0] = i;
SAM[flag][1] = j;
SAM[flag][2] = TDA[i][j];
}
}
}
return SAM;
}
利用输入输出流来做（此处有借鉴其他视频及博文）
//从文件读入数组
public static int[][] readFromFile(String Path) throws IOException {
File file = new File(Path);
int[][] SMA = null;
BufferedReader bufferedReader = null;
try {
bufferedReader = new BufferedReader(new FileReader(file));
//获取稀疏数组大小
int sum = 0;
while (bufferedReader.readLine() != null) {
sum++;
}
SMA = new int[sum][3];
//读完以后关闭流，防止后面读到的为空
bufferedReader.close();
//打开流
bufferedReader = new BufferedReader(new FileReader(file));
String strs = bufferedReader.readLine();
int i = 0;
int j = 0;
while (strs != null) {
String[] str = strs.split(" ");
for(String s :str){
SMA[i][j] = Integer.parseInt(s);
j++;
}
j = 0;
i++;//行指针自增
}
} catch (IOException e) {
e.printStackTrace();
} catch (NumberFormatException e) {
e.printStackTrace();
}
if(bufferedReader != null) bufferedReader.close();
return SMA;
}
1、通过稀疏数组的第一行，新建二维数组。
2、遍历稀疏数组，根据第2-n行数据将有效值赋值给二维数组
//稀疏数组转二维数组
public static int[][] SparseMartixToTwoDimensional(int[][] SparseMartixArray) {
int[][] SAM = SparseMartixArray;
//根据稀疏数组的第一行初始化得到二维数组
int[][] TDA = new int[SAM[0][0]][SAM[0][1]];
//根据稀疏矩阵数据还原
for (int i = 1; i < SAM.length; i++) {
TDA[SAM[i][0]][SAM[i][1]] = SAM[i][2];
}
return TDA;
}
//将数据写入文件中
public static void writeTotext(int[][] array, String path) {
File file = new File(path);
//创建字符输出流
FileWriter writer = null;
try {
writer = new FileWriter(file, true);
//写数据
for (int i = 0; i < array.length; i++) {
writer.write(array[i][0] + " ");
writer.write(array[i][1] + " ");
writer.write(array[i][2] + " " + "\n");
}
} catch (IOException e) {
e.printStackTrace();
}
//关闭流
if (writer != null) {
try {
writer.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
package SparseMatrix;
import java.io.*;
import java.util.Scanner;
/**
* @author fuyaling
* @create 2022-06-28-17:07
* 稀疏矩阵的代码实现
*/
public class SparseMartrix {
public static void main(String[] args) {
//新建scanner对象接收输入
Scanner scanner = new Scanner(System.in);
//获取数组行数
int m = scanner.nextInt();
//获取数组列数
int n = scanner.nextInt();
//初始化m行n列的数组
int[][] arry = InitialValue(m, n);
//输出原数组
PrintArry(arry);
//转稀疏数组
int[][] SparseMartix = TwoDimensionalToSparseMartix(arry);
//输出转后的系数数组
PrintArry(SparseMartix);
//稀疏数组转二维数组
int[][] TDA = SparseMartixToTwoDimensional(SparseMartix);
PrintArry(TDA);
}
//遍历二维数组
public static void PrintArry(int[][] arry) {
if (arry != null) {
for (int i = 0; i < arry.length; i++) {
for (int j = 0; j < arry[i].length; j++) {
System.out.print(arry[i][j]);
}
System.out.println();
}
}
}
//获取原数组并赋值
public static int[][] InitialValue(int m, int n) {
//新建m行n列的二维数组
int[][] arry = new int[m][n];
for (int i = 0; i < m; i++) {
for (int j = 0; j < n; j++) {
if (j == i - 1) {
arry[i][j] = i;
}//else arry[i][j] = 0;
}
}
return arry;
}
//二维数组转稀疏数组
public static int[][] TwoDimensionalToSparseMartix(int[][] TwoDimensionalArray) {
int[][] TDA = TwoDimensionalArray;
int count = 0;
//循环内遍历得到二维数组内的有效值个数
//用来新建数组时候，确定数组行数
for (int i = 0; i < TDA.length; i++) {
for (int j = 0; j < TDA[0].length; j++) {
if (TDA[i][j] != 0) {
count++;
}
}
}
int[][] SAM = new int[count + 1][3];
SAM[0][0] = TDA.length;
SAM[0][1] = TDA[0].length;
SAM[0][2] = count;
int flag = 0;
//循环赋值
for (int i = 0; i < TDA.length; i++) {
for (int j = 0; j < TDA[0].length; j++) {
if (TDA[i][j] != 0) {
SAM[++flag][0] = i;
SAM[flag][1] = j;
SAM[flag][2] = TDA[i][j];
}
}
}
return SAM;
}
//稀疏数组转二维数组
public static int[][] SparseMartixToTwoDimensional(int[][] SparseMartixArray) {
int[][] SAM = SparseMartixArray;
//根据稀疏数组的第一行初始化得到二维数组
int[][] TDA = new int[SAM[0][0]][SAM[0][1]];
//根据稀疏矩阵数据还原
for (int i = 1; i < SAM.length; i++) {
TDA[SAM[i][0]][SAM[i][1]] = SAM[i][2];
}
return TDA;
}
//从文件读入数组
public static int[][] readFromFile(String Path) throws IOException {
File file = new File(Path);
int[][] SMA = null;
BufferedReader bufferedReader = null;
try {
bufferedReader = new BufferedReader(new FileReader(file));
//获取稀疏数组大小
int sum = 0;
while (bufferedReader.readLine() != null) {
sum++;
}
SMA = new int[sum][3];
//读完以后关闭流，防止后面读到的为空
bufferedReader.close();
//打开流
bufferedReader = new BufferedReader(new FileReader(file));
String strs = bufferedReader.readLine();
int i = 0;
int j = 0;
while (strs != null) {
String[] str = strs.split(" ");
for (String s : str) {
SMA[i][j] = Integer.parseInt(s);
j++;
}
j = 0;
i++;//行指针自增
}
} catch (IOException e) {
e.printStackTrace();
} catch (NumberFormatException e) {
e.printStackTrace();
}
if (bufferedReader != null) bufferedReader.close();
return SMA;
}
//将数据写入文件中
public static void writeTotext(int[][] array, String path) {
File file = new File(path);
//创建字符输出流
FileWriter writer = null;
try {
writer = new FileWriter(file, true);
//写数据
for (int i = 0; i < array.length; i++) {
writer.write(array[i][0] + " ");
writer.write(array[i][1] + " ");
writer.write(array[i][2] + " " + "\n");
}
} catch (IOException e) {
e.printStackTrace();
}
//关闭流
if (writer != null) {
try {
writer.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
编码养成良好习惯，特别是Java学习，对于复用性高，容易造成不必要冗余的且能封装的方法尽量封装。