import java.io.*;

public class Append1 
{
  public static void main(String[] args)
  {
    String filename= "C:\\file.txt" ;
    
    System.out.print( "Use file : "  + filename);
   
//  1  вариант
    try{
       FileWriter sw = new FileWriter(filename,true);
       sw.write( "Add this text to the end of datafile by FileWriter"  +  "\n" );
       sw.close();
    }catch(Exception e){
       System.out.print(e.getMessage());
   }    

//  2 -ой вариант
    try {
    RandomAccessFile file = new RandomAccessFile(filename,  "rw" );
    file.skipBytes((int)file.length()); //skip to the end of the file
    file.writeBytes( "Add this text to the end of datafile by RandomAccessFile\n" );       
    file.close();
    }catch(Exception e){
     System.out.print(e.getMessage());
   }    

//  3 -ий вариант
    PrintStream out = null;
    
    try {
     out = new PrintStream(
              new BufferedOutputStream(
               new FileOutputStream(filename, true)));
     out.println( "Add this text to the end of datafile by FileOutputStream" );
    } catch(IOException e) {
     e.printStackTrace();
    } finally {
       if (out != null) {
         out.close();
       }
   }
   
  }
}