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I need a way to save an ArrayList of objects. I have browsed similar issues in the site and I (seem ;-) to have implemented what I found, but I get two problems:

  1. If I define the class as Serializable and put the constructor, it crashes at launch
  2. Otherwise, It does not save the array

Can you please help? I am developing code for a volunteer's project and I am stuck...

Thank you a lot in advance.

My application has the following defined class: Globals (file Globals.java)

public class Globals extends Application implements Serializable {  

    private int position=-1;
    private ArrayList<RaccoltaPunti> raccoltePuntiList = new ArrayList<RaccoltaPunti>();
    public static final long serialVersionUID = 1L;
    /** constructor - seem required by Serializable, but creating it crashes app */
    public Globals(int position, ArrayList<RaccoltaPunti> raccoltePuntiList) {
        this.position = position;
        this.raccoltePuntiList = raccoltePuntiList;
    }
     // {getters and setters…}

    public void saveData(){

        String filename = getResources().getString(R.string.GLB_filename);
        String fileWithPath = this.getFilesDir().getPath().toString()+"/"+filename;
        Toast.makeText(this, "Salvataggio testo..."+ fileWithPath, Toast.LENGTH_LONG).show();
        try {
            FileOutputStream fos = new FileOutputStream(fileWithPath);
            ObjectOutputStream oos = new ObjectOutputStream(fos);
            oos.writeObject(this.raccoltePuntiList);    
            oos.close();
            Toast.makeText(Globals.this, "DatiSalvati ", Toast.LENGTH_SHORT).show();
        } catch (IOException e) {
            Log.e("FileSave", "CDM - IOException", e);
            Toast.makeText(this, "Errore saving file", Toast.LENGTH_LONG).show();
        }
    }
}

The class referenced is: RaccoltaPunti.java

public class RaccoltaPunti {

    private String nomeRaccolta;
    private String nomePromoter;
    private String numeroTessera;
    private Long puntiPusseduti;
    private String dataScadenzaPunti;
    private String sitoWeb;
    private String sitoWebUsername;

        // constructor, getters and setters…….
}
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2
  • can you post the stacktrace when it crashes? Commented Aug 24, 2012 at 12:12
  • The exception tells you exactly what is wrong. Don't just ignore it, and don't just reduce every error you see to 'application crash'. Commented Aug 25, 2012 at 10:19

3 Answers 3

Reset to default
2
  • If you want to save the list RaccoltaPunti must be Serializable.
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1 Comment

Tahnk you all!I will try and let you know.
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Try creating a default constructor : 

public Globals(){

}

Since the class extends Application class, it will be called from outside through reflection and it might expect for a default constructor. By default, if you are not writing any constructor, default constructor will be there already.

Make RaccoltaPunti also Serializable

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4 Comments

A default constructor is not required in a serializable class. 'Try' and 'might' indicate guesswork. The final sentence contradicts the others. Not an answer.
@EJB.Hope you see "If I define the class as Serializable and put the constructor, it crashes at launch". That crash is because its an Application class and it doesn't have a default constructor. Being an Application class it is supposed to be entered in the manifest file and that means the android System is calling it. So definitely i can say, it is using reflection to call it. Bu default, When Android tries to create an instance of the application class using reflection, it is looking for the default constructor. So I mentioned about the default and not coz of Serialization. Read CAREFULLY!!
@EJP : Try creating an application class with a parameterized constructor and mention it in the Manifest file, you can see whether I'm correct or not, You will get "java.lang.RuntimeException" stating "no empty constructor". The one thing that you said above is correct..."Guess Work". But now I tried and I'm sure that I'm correct (Not about serialization but about the crash). I respect your reputation in Stack overflow, but being a good Technical guy means you need to listen to others even what ever foolish they were speaking...
Dear all,I was in the impossibility to test in the last days. I will check your valuable suggestions and give you feedback as soon as possible.
0


The problem seems resolved (now the file is successfully saved without errors and by manually opening it it seems to contain all the info).
Thank you to you all.

I summarise the solution for the benefit of any other future reader with the same issue.

The problem was resolved by making the class RaccoltaPunti Serializable, as per following code fragment:

    import java.io.Serializable;
    ...

    public class RaccoltaPunti implements Serializable {
    ...

I noted that RaccoltaPunti had already a constructor with parameters:

    public  RaccoltaPunti(
        String nomeRaccolta,
        String nomePromoter,
        String numeroTessera,
        Long puntiPusseduti,
        String dataScadenzaPunti,
        String sitoWeb,
        String sitoWebUsername) {



For reference, the error reported in the log was referring to the line of code:

    oos.writeObject(this.raccoltePuntiList);



Regarding the constructor for the Globals class, my experiments showed that everything is working by just commenting it out. I did not try all possible combinations (i.e. with or without parameters): I just removed it.

Thank you all who helped.

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