Introduction to Java file reading and writing operations

Simple reading and writing of files

package com.file;

import java.io.*;

/**
 * Created by elijahliu on 2017/2/11.
 */
public class ReadFile {
  public static void main(String[] args) {
    File file = new File("new Hello.txt");
    if(file.exists()){
      System.err.print("exsit");
      try (FileInputStream fis = new FileInputStream(file)) {//文件输入流 这是字节流

        InputStreamReader isr = new InputStreamReader(fis,"UTF-8");//inputstreamReader是一个字节流，将字节流和字符流转化的时候，就需要制定一个编码方式，不然就会乱码
        BufferedReader br = new BufferedReader(isr);//字符缓冲区

        String line;
        while((line = br.readLine())!=null){//这里将缓冲区里的内容如果非空就读出来打印
          System.out.println(line);

        }
        br.close();//最后将各个线程关闭
        isr.close();
        fis.close();
      } catch (FileNotFoundException e) {
        e.printStackTrace();
      } catch (IOException e) {
        e.printStackTrace();
      }
    }
    File newfile = new File("newtext.txt");
    try {
      FileOutputStream fos = new FileOutputStream(newfile);//这里如果文件不存在会自动创建文件
      OutputStreamWriter osw = new OutputStreamWriter(fos, "UTF-8");//和读取一样这里是转化的是字节和字符流
      BufferedWriter bw = new BufferedWriter(osw);//这里是写入缓冲区

      bw.write("厉害了我的哥");//写入字符串

      bw.close();//和上面一样 这里后打开的先关闭 先打开的后关闭
      osw.close();
      fos.close();
      System.out.println("done");
    } catch (FileNotFoundException e) {
      e.printStackTrace();
    } catch (UnsupportedEncodingException e) {
      e.printStackTrace();
    } catch (IOException e) {
      e.printStackTrace();
    }

  }
}

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