java 文件读写demo

分析错误日志：

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

public class tongji {

    @SuppressWarnings({ "unused" })
    public static void main(String[] args) throws IOException {
        //error.log-2017-02-24
         StringBuffer sb= new StringBuffer("");

         FileReader reader = new FileReader("D:\\document\\error.log-2017-02-24");
         BufferedReader br = new BufferedReader(reader);

         String str = null;

         while((str = br.readLine()) != null) {
               if(str.length()>80){
                   System.out.println(str);
               }
         }
         br.close();
         reader.close();
    }
}