Java 读取文件字符串和本身设置的字符串长度不相等

用java读取文件中的值并做比较，发现竟然不一样！！这让我当时百思不得其解，还以为是IDEA出现了问题呢

话不多说看代码

import java.io.*;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

public class MatchingData {

    private static ArrayList<String> bankfin = new ArrayList<>();

    public static void main(String[] args)  {

        ArrayList<String> banksall = readFileByLines("C:\\Users\\EDZ\\Desktop\\banks.txt");

        HashMap<String, String> bankallMap = new HashMap<>();
        for (int n = 0; n<banksall.size();n++){
            String[] split = banksall.get(n).split(",");

            bankallMap.put(split[1],split[0]);
        }


        ArrayList<String> banksli = readFileByLines("C:\\Users\\EDZ\\Desktop\\littlebank.txt");



        for (int i = 0 ;i<banksli.size();i++){

            //将少数银行数据的表 通过，切割
            String[] bankslittle = banksli.get(i).split(",");

            String aa = bankslittle[0].trim().replaceAll("\\uFEFF","");

            System.out.println(aa.length());


            String bankname ;
            bankname = bankallMap.getOrDefault(aa,"-");

            //  System.out.println(bankname+".....");

            if (bankname.equals("-")){

                bankname =  bankallMap.getOrDefault(aa.substring(0,aa.length()-1)+"股份有限公司'","-");

                //   System.out.println(bankname+"/////");

                if(bankname.equals("-")){
                    bankname = (String) bankallMap.getOrDefault((aa.substring(0,aa.length()-1)+"有限责任公司'"),"-");

                    // System.out.println(bankname+";;;;;;;;;");

                    if(bankname.equals("-")){

                        String concat = banksli.get(i).toString().concat(",null");

                        bankfin.add(concat);
                    }else{
                        String bankkey = aa.substring(0, aa.length() - 1) + "有限责任公司',";
                        String concat= bankkey+ bankslittle[1] + "," + bankallMap.get(bankkey.substring(0,bankkey.length()-1));
                        bankfin.add(concat);
                    }

                }else {

                    String bankkey = aa.substring(0, aa.length() - 1) + "股份有限公司',";
                    String concat= bankkey + bankslittle[1] + "," + bankallMap.get(bankkey.substring(0,bankkey.length()-1));
                    bankfin.add(concat);
                }

            }else {
                String concat = banksli.get(i).toString().concat("," + bankallMap.get(aa));
                bankfin.add(concat);
            }


        }

            writeFileByLines("C:\\Users\\EDZ\\Desktop\\test.txt");


    }

    public static ArrayList<String> readFileByLines(String fileName) {
        File file = new File(fileName);
        BufferedReader reader = null;
        ArrayList<String> list1 = new ArrayList<>();

        try {
            reader = new BufferedReader(new FileReader(file));
            String tempString = null;
            int line = 1;
            // 一次读一行，读入null时文件结束
            while ((tempString = reader.readLine()) != null) {
                // Thread.sleep(1);
                //System.out.println(tempString);
                list1.add(tempString);
                line++;
            }
            reader.close();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (reader != null) {
                try {
                    reader.close();
                } catch (IOException e1) {
                    e1.printStackTrace();
                }
            }
            return list1;
        }

    }

    public static void writeFileByLines(String fileName){
        File file = new File(fileName);  //存放数组数据的文件
        // FileWriter out = null;
        BufferedWriter bw =null;
        FileOutputStream writerStream = null;
        try {
            writerStream = new FileOutputStream(file);
            bw = new BufferedWriter(new OutputStreamWriter(writerStream, "UTF-8"));
        } catch (Exception e) {
            e.printStackTrace();
        }

        for(int m = 0;m<bankfin.size();m++){
            try {
                bw.write(bankfin.get(m));
                bw.newLine();

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


            System.out.println( "写入成功");
        }

        try {
            bw.close();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
}


打印结果

文件字符串：中国银行
文件字符串长度：5
-------------------------
本身设置字符串：中国银行
本身设置字符串长度：4

最后发现原来是两个文件的编码格式不太一样，一个是UTF8无BOM格式，一个是UTF8格式，这两种格式虽然都是UTF8，但还是有区别的，在Windows下用文本编辑器创建的文本文件，如果选择以UTF-8等Unicode格式保存，会在文件头（第一个字符）加入一个BOM标识（从第二行开始便没有这个BOM标识了）。

解决 ：
将utf8的bom格式去掉
s.trim().replaceAll("\uFEFF","");