Java文件写入与读取实例求最大子数组

出现bug的点：输入数组无限大；

输入的整数，量大：

解决方案：向文件中输入随机数组，大小范围与量都可以控制。

源代码：

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.ArrayList;
import java.util.Random;

public class XieRuDuQu {
public static void main(String[] args) throws IOException{
  writeRandomByOutputStreamWriter("D:\\data.txt");
        System.out.println("最大子数组:"+max(readArrayByInputStreamReader("D:\\data.txt")));//输出最大子数组
    }

public static int max(int a[]) {
  /**
   * 求一维数组最大子数组
   */
  int x=a.length;
  int b[][]=new int[x][x];//存子数组
  int c[]=new int[x];//存二维数组每一行的最大值
  for(int i=0;i<x;i++) {//所有子数组存入二维数组中：以第i个开头的子数组们存入第i行
   for(int j=0;j<x;j++) {//求出二维数组的一行
    int sum=0;
    for(int s=i;s<=j;s++){//求每一个子数组
    sum+=a[s];
    }
    b[i][j]=sum;//存子数组
   }
  };
  for(int i=0;i<x;i++) {//i为行
   for(int j=0;j<x;j++) {//j为列
       if(b[i][j]>c[i]) {
        c[i]=b[i][j];
       }
   }
  }
  int s=0;
  for(int i=0;i<c.length;i++) {

   if(s<c[i]) {
    s=c[i];
   }
  };
  return s;
    }
public static int[] readArrayByInputStreamReader(String txt) {
  /**
   *读取
   */
  ArrayList arrayList = new ArrayList<>();
  try {
   String encoding = "UTF-8";
      File file = new File(txt);
      InputStreamReader read = new InputStreamReader(new FileInputStream(file), encoding);
   BufferedReader bufferedReader = new BufferedReader(read);
   if (file.isFile() && file.exists()) {
    String temp;
    while ((temp = bufferedReader.readLine()) != null) {
     arrayList.add(temp);
     }
    bufferedReader.close();
    read.close();
   }
  }catch (Exception e) {
   e.printStackTrace();
  }
   // 对ArrayList中存储的字符串进行处理
        int length = arrayList.size();
        int[] array = new int[length];
        for (int i = 0; i < length; i++) {
        String s = arrayList.get(i);
        array[i] = Integer.parseInt(s);
        }
  return array;
}
public static void writeRandomByOutputStreamWriter(String txt) {
  /**
    * 文件写入随机数
       */
       try {
      String encoding = "UTF-8";
   File file = new File(txt);
           if(!file.exists())
           {   //如果不存在data.txt文件则创建
               file.createNewFile();
               System.out.println("文件创建完成");
           }
           OutputStreamWriter write = new OutputStreamWriter(new FileOutputStream(file), encoding);
   BufferedWriter bufferedWriter = new BufferedWriter(write);
           //产生随机数据，写入文件
           Random random = new Random();
           for(int i=0;i<10;i++)
           {
               int randint =(int)Math.floor((random.nextDouble()*100.0));   //产生0-10000之间随机数
               bufferedWriter.write(String.valueOf(randint));      //写入一个随机数
               bufferedWriter.newLine();       //新的一行
           }
           bufferedWriter.close();
           write.flush();
           write.close();


     }catch (Exception e) {
    e.printStackTrace();
   }

}
}