import java.io.*;
public class  Test2{    
    public static void main(String[] args){
        FileOutputStream fos = null ;
        try{
            fos = new FileOutputStream("F:\\java_ex\\abc.txt");
        }catch(FileNotFoundException fnf){
            fnf.printStackTrace();
        }
        for(int i='A';i<'Z';i++){
            try{
                fos.write(i);
                fos.close();
            }catch(IOException ioe){
                ioe.printStackTrace();
            }
        }
    }
}