JAVA读取文件内容生成文件txt

package tuohang.ces;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;

public class erlangshen {
public static void main(String[] args) throws IOException, InterruptedException {
//readFilePath就是读取的txt文件夹
    String readFilePath="G:\\360MoveData\\Users\\123\\Desktop\\数据处理平台2.0\\TestData\\供应商筛选";
//writerFilePath是将合并的txt文件夹输出到那个目录下
    String writerFilePath="G:\\360MoveData\\Users\\123\\Desktop\\数据处理平台2.0\\TestData\\供应商筛选-合并10个txt"+"\\";
    File file = new File(readFilePath);
    File[] listFiles = file.listFiles();
    int a=0;
    
    StringBuffer stringBuffer = new StringBuffer();
    

    

for (int i = 0; i < listFiles.length; i++) {
    System.out.println(listFiles[i]);
    ddd(listFiles,i,stringBuffer);
    System.out.println(i);
    System.out.println(a);
    if(a==9) {
        System.out.println(i);
        System.out.println(a);
         File file2 = new File(writerFilePath+i+".txt");
         file2.createNewFile();
         FileWriterDemo(stringBuffer,file2);
         stringBuffer.setLength(0);
        a=-1;
    }
    a++;
}
System.out.println("完成");
}
public static void FileWriterDemo(StringBuffer content,File file2){
    try(
        FileWriter fileWriter = new FileWriter(file2)) {
        fileWriter.append(content);
    } catch (Exception e) {
        e.printStackTrace();
    }

}
public static void ddd(File[] listFiles,int i,StringBuffer stringBuffer) throws IOException {
    FileInputStream fin = new FileInputStream(listFiles[i]);
    InputStreamReader reader = new InputStreamReader(fin);
    BufferedReader buffReader = new BufferedReader(reader);
    String strTmp = "";
    while((strTmp = buffReader.readLine())!=null){
        stringBuffer.append(strTmp+System.getProperty("line.separator"));
    }
    reader.close();
    buffReader.close();
}
}