Name not displaying in program

Guys,
I have a question for you all. I'm writing a random access file, that will
take my input and store the information to the file.
This is my output from the program. The last name isn't showing at all. I
know it has to do with string buffer. Please let me know what i can do?

Account number First Name Last Name
3 Jeff : 0

 // read a record from the specified RandomAccessFile
   public void read( RandomAccessFile file ) throws IOException
   {
      setAccountNumber(file.readInt());
      setFirstName( padName( file ) );
      setLastName( padName( file ) );
   }

   // ensure that name is proper length
   private String padName( RandomAccessFile file ) throws IOException
   {
      char name[] = new char[ 30 ];

      for ( int i = 0; i < name.length; i++ )
         name[ i ] = file.readChar();

      return new String( name ).replace( '\0', ' ' );
   }
    // write a record to the specified RandomAccessFile
   public void write( RandomAccessFile file ) throws IOException
   {
      file.writeInt( getAccountNumber() );

      StringBuffer buffer;

      if ( FirstName != null )
         buffer = new StringBuffer( FirstName );
      if ( LastName != null )
          buffer = new StringBuffer( LastName );

      else
         buffer = new StringBuffer(30);

        buffer.setLength( 30 );

      file.writeChars( buffer.toString() );

       }