write object to file java -

i creating application manages agenda. each contact must written in object file. how can check if file exists , there way write next object without overwriting??

my class:

import java.io.*;  public class writefile {     public void setcontact(agenda contact){         objectoutputstream out;          try{             file file = new file("contacts.txt");             out = new objectoutputstream(new fileoutputstream(file));             out.writeobject(contact);               out.flush();             out.close();             system.out.println("object written file");         }         catch (filenotfoundexception ex) {             system.out.println("error specified file") ;             ex.printstacktrace();         }         catch (ioexception ex) {             system.out.println("error i/o processes") ;             ex.printstacktrace();         }                  }  } 

using code, believe easiest thing make use of file.exists() method check see if file exists.

boolean exists = file.exists(); 

then can use following constructor the fileoutputstream:

public fileoutputstream(file file, boolean append) throws filenotfoundexception 

to append end of file. construction of object should wrapped in if-else clause, depending on value of file.exists().