Convert sparse array to disk and read out the array (Silicon Valley Data Structure Notes)
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The code is as follows (example):
package com.Array;
import java.io.*;
import java.util.Arrays;
public class SparseArr {
public static void main(String[] args) {
// 创建一个原始的二维数组11*11
// 0：表示没有棋子，1表示黑子2表蓝子
int chessArr[][] = new int[11][11];
chessArr[1][2] = 1;
chessArr[2][4] = 2;
//转换稀疏数组
int[][] sparse = toSparse(chessArr);
for (int[] inner : sparse) {
for (int data : inner) {
System.out.printf("%d\t",data);
}
System.out.println();
}
saveArray(sparse);
//还原数组
System.out.println();
int[][] array = toArray(sparse);
for (int[] inner : array) {
for (int data : inner) {
System.out.printf("%d\t",data);
}
System.out.println();
}
System.out.println();
int[][] loadArray = loadArray();
for (int[] inner : loadArray) {
for (int data : inner) {
System.out.printf("%d\t",data);
}
System.out.println();
}
}
/**
*
* @param sparse 稀疏数组（还原）
*/
private static int[][] toArray(int[][] sparse) {
int row = sparse[0][0];
int column = sparse[0][1];
//建立好待还原数组
int[][] array = new int[row][column];
//稀疏数组值填充待还原数组
for (int i = 1;i < sparse.length;i++){
//计算元素在待还原数组的坐标和值
int x = sparse[i][0];
int y = sparse[i][1];
int value = sparse[i][2];
array[x][y] = value;
}
return array;
}
/**
*
* @param array 普通数组转换稀疏数组
* @return
*/
public static int[][] toSparse(int[][] array){
//计算数组中不为0的个数
int sum = 0;
for (int[] inner : array) {
for (int i = 0;i < inner.length;i++){
if (inner[i] != 0){
sum ++;
}
}
}
//创建稀疏数组
int[][] sparseArray = new int[sum + 1][3];
//初始化第一行
sparseArray[0][0] = array[array.length-1].length;
sparseArray[0][1] = array.length;
sparseArray[0][2] = sum;
//把数据存入稀疏数组
//count用来计数
int count = 0;
for (int i = 0; i < array.length;i++){
for (int j = 0; j < array[i].length; j++){
if (array[i][j] != 0){
++count;
sparseArray[count][0] = i;
sparseArray[count][1] = j;
sparseArray[count][2] = array[i][j];
}
}
}
return sparseArray;
}
//保存数组
public static boolean saveArray(int[][] array){
File file = null;
FileWriter writer = null;
try {
//我是Mac系统路径，注意要是win系统可能修改路径符号
file = new File("./src/main/resources/map.txt");
if (!file.exists()){
file.createNewFile();
}
writer = new FileWriter(file,true);
for (int[] inner : array) {
for (int data : inner) {
writer.write( data + "\t");
}
writer.write("\n");
}
return true;
}catch (Exception e){
e.printStackTrace();
return false;
}finally {
if (writer != null){
try {
writer.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
//加载数组到内存中
public static int[][] loadArray(){
File file = null;
FileReader reader = null;
//先把文件里的数据存buffer里
StringBuffer buffer = new StringBuffer();
try {
file = new File("./src/main/resources/map.txt");
reader = new FileReader(file);
int len = 0;
char[] data = new char[10];
while ((len = reader.read(data)) != -1){
for (int i = 0; i < len;i++){
buffer.append(data[i]);
}
}
}catch (Exception e){
e.printStackTrace();
}finally {
if (reader != null){
try {
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
//将buffer转换string
String result = new String(buffer);
//正则表达式拆分字符串（拆每行）
String[] row = result.split("\n");
//拆0行有多少列 为new
String[] col = row[0].split("\t");
//准备填充数组准备 返回returnArray确定列树木
int[][] returnArray = new int[row.length][col.length];
for (int i = 0;i < row.length;i++){
//拆分每行
String[] column = row[i].split("\t");
for (int j = 0;j < column.length;j++){
//将string转换int类型
returnArray[i][j] = Integer.parseInt(column[j]);
}
}
return returnArray;
}
}
Summarize
提示：关于IO读写你可以加缓冲流加快读写速度：代码参考尚硅谷老师代码完成的