java 字符流writer、reader基本操作及理解
时间:2014-05-03 23:57:18
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字符和字节有什么区别,额……这个我也不知道。
1、基本操作实例
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、注意的问题
将out.close();注释掉
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();
}
}
}
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