Basic operations and understanding of java producer stream writer and reader

What is the difference between a character and a byte ...... I don't know.

1. Basic operation instance

import java.io.*;public class CharDemo{public static void main(String[] args){File f=new File("F:\\workspace\\Javaprj\\test.txt");Writer out=null;Reader in=null;try{out=new FileWriter(f);String str="Hello World!!!";out.write(str);System.out.println("The string "+"\"Hello World!!!\""+" has been written into "+f.getName()+".");out.close();in=new FileReader(f);char[] buf=new char[1024];int num=in.read(buf);if(num!=-1){System.out.println("The string \""+ new String(buf,0,num) +"\" has been read from the file "+f.getName()+".");}else{System.out.println("The file \""+f.getName()+"\" is empty!");}}catch(IOException e){e.printStackTrace();}}}

2. Notes

Comment out. close ();

import java.io.*;public class CharDemo{public static void main(String[] args){File f=new File("F:\\workspace\\Javaprj\\test.txt");Writer out=null;Reader in=null;try{out=new FileWriter(f);String str="Hello World!!!";out.write(str);System.out.println("The string "+"\"Hello World!!!\""+" has been written into "+f.getName()+".");//out.close();in=new FileReader(f);char[] buf=new char[1024];int num=in.read(buf);if(num!=-1){System.out.println("The string \""+ new String(buf,0,num) +"\" has been read from the file "+f.getName()+".");}else{System.out.println("The file \""+f.getName()+"\" is empty!");}}catch(IOException e){e.printStackTrace();}}}