[Java] PrintWriter

import java.io.*; public class CopyFileTest4{     public static void main(String[] args) throws IOException{         FileReader fr = new FileReader("CopyFileTest4.java");         BufferedReader br = new BufferedReader(fr);                 FileWriter fw = new FileWriter("temp.txt");         PrintWriter pw = new PrintWriter(fw);                 String read = br.readLine();         while(read!=null){             pw.println(read);             read = br.readLine();         }         pw.flush();         pw.close();     } } //PrintWriter可以提供println()方法,直接输出一行