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Java Java Data Structures - Retired Efficiency! Custom Serialization

Matthew Francis
Matthew Francis
6,967 Points
Posted by Matthew Francis
Matthew Francis
6,967 Points

Newbie - Serialization, Why not use system.out.printf() instead of PrintWriter.printf()?

  public void exportTo(String fileName){
    try(
      fileOutputStream fos = new FileOutputStream(fileName);
      PrintWriter writer = new PrintWriter(fos);//PrintWriter prints formatted representations of objects to a text-output stream., 
                                                  we used ToString(), so printWriter works
    ){
      for(Song song : mSongs){
        writer.printf("%s|%s|%s %n", song.getArtist(), song.getTitle(). song.getVideoUrl());
       //Why not use system.out.printf()? Why use PrintWriter.printf()?
      }
    }catch(IOException ioe){
      System.out.printf("Problem saving %s %n", fileName);
      ioe.printStacktrace();
    }
  }

3 Answers

Matthew Francis
Matthew Francis
6,967 Points
Matthew Francis
Matthew Francis
6,967 Points

Thanks, one question though, why do you want to write it to a file? I'm guessing it's something relating to serialization/deserilization?

Alexander Nikiforov
seal-mask
.a{fill-rule:evenodd;}techdegree seal-36
Alexander Nikiforov
Java Web Development Techdegree Graduate 22,175 Points
Alexander Nikiforov
.a{fill-rule:evenodd;}techdegree seal-36
Alexander Nikiforov
Java Web Development Techdegree Graduate 22,175 Points

No I think, no serialization here. when you write:

writer.printf("%s|%s|%s %n", song.getArtist(), song.getTitle(). song.getVideoUrl());

All you get: is simple line "Artist|Title|VideoUrl" in file. Text file.

If you want to save something using serialization, then you have to use the code, like here:

http://www.tutorialspoint.com/java/java_serialization.htm

import java.io.*;

public class SerializeDemo
{
   public static void main(String [] args)
   {
      Employee e = new Employee();
      e.name = "Reyan Ali";
      e.address = "Phokka Kuan, Ambehta Peer";
      e.SSN = 11122333;
      e.number = 101;

      try
      {
         FileOutputStream fileOut =
         new FileOutputStream("/tmp/employee.ser");
         ObjectOutputStream out = new ObjectOutputStream(fileOut);
         out.writeObject(e);
         out.close();
         fileOut.close();
         System.out.printf("Serialized data is saved in /tmp/employee.ser");
      }catch(IOException i)
      {
          i.printStackTrace();
      }
   }
}

You see how ObjectOutputStream is used. I haven't tried that myself, but I do believe this code, and in the video, Crais save files just as text

Colby Wise
Colby Wise
3,165 Points
Colby Wise
Colby Wise
3,165 Points

Alexander - so to help me break this down into layman's terms: you use serialization to [read / write] text files / data? Or what's the big idea or purpose for it. What are the benefits of someone implementing serialization?

Colby Wise
Colby Wise
3,165 Points
Colby Wise
Colby Wise
3,165 Points

As always, thanks AN