java FileReader与FileWriter 代码笔记

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.Reader;
import java.text.FieldPosition;

public class FileReaderWriter {
//FielRader 用于读取纯文本文件
    public static void main(String[] args) {

                    //读取与拷贝
                    try {
                        FileReader fr=new FileReader("data.txt");
                        BufferedReader br=new BufferedReader(fr);

                        FileWriter fw=new FileWriter("data.txt");
                        BufferedWriter bw=new BufferedWriter(fw);

                        String line;
                        while((line=br.readLine())!=null){
                            bw.write(line);//写出
                        }
                        bw.flush();  //强制输出
                        bw.close();
                        fw.close();
                        br.close();
                        fr.close();

                    } catch (FileNotFoundException e) {

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


    }

}