read：

import java.io.FileReader; //導入包
import java.io.IOException; //導入包

public class read {

package com.chinasoft.java.wangluobiancheng;

import java.io.FileReader;
import java.io.IOException;

public class read {
    
    public static void main(String []args)throws IOException{
        
            FileReader f2
 
=new FileReader("haha1.txt");
            int i= f2.read();
            while(i!=-1){
                System.out.print((char)i);
                i=f2.read();
            }
            //while((f2.read())!=-1){
            //    System.out.print((char)f2.read());
            //}
            f2.close();
        }
    }
 

write:

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
public class write {

    public static void main(String[] args) throws IOException {
        // TODO Auto-generated method stub

        FileWriter f1=new FileWriter("haha1.txt");        
        String str="hahahha";
        f1.write(
 
"hahahha");
        f1.flush();
        f1.close();
    }
    }

read 和write