How to send objects through bundle

Question

I need to pass a reference to the class that does the majority of my processing through a bundle   The problem is it has nothing to do with intents or contexts and has a large amount of non-primitive objects  How do I package the class into a parcelable serializable and pass it to a startActivityForResult

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Possible solution   Bundle bundle   new Bundle    bundle putSerializable  key   new CustomObject       Class CustomObject   class CustomObject implements Serializable   private SubCustomObject1 sc1   private SubCustomObject2 sc2      Subcustom objects   class SubCustomObject1 implements Serializable     class SubCustomObject2  implements Serializable

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You can also use Gson to convert an object to a JSONObject and pass it on bundle  For me was the most elegant way I found to do this  I haven t tested how it affects performance   In Initial Activity  Intent activity   new Intent MyActivity this NextActivity class   activity putExtra  myObject   new Gson   toJson myobject    startActivity activity     In Next Activity  String jsonMyObject  Bundle extras   getIntent   getExtras    if  extras    null       jsonMyObject   extras getString  myObject      MyObject myObject   new Gson   fromJson jsonMyObject  MyObject class

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Figuring out what path to take requires answering not only CommonsWare s key question of  why  but also the question of  to what   are you passing it   The reality is that the only thing that can go through bundles is plain data - everything else is based on interpretations of what that data means or points to   You can t literally pass an object  but what you can do is one of three things   1  You can break the object down to its constitute data  and if what s on the other end has knowledge of the same sort of object  it can assemble a clone from the serialized data   That s how most of the common types pass through bundles   2  You can pass an opaque handle   If you are passing it within the same context  though one might ask why bother  that will be a handle you can invoke or dereference   But if you pass it through Binder to a different context it s literal value will be an arbitrary number  in fact  these arbitrary numbers count sequentially from startup    You can t do anything but keep track of it  until you pass it back to the original context which will cause Binder to transform it back into the original handle  making it useful again   3  You can pass a magic handle  such as a file descriptor or reference to certain os platform objects  and if you set the right flags Binder will create a clone pointing to the same resource for the recipient  which can actually be used on the other end   But this only works for a very few types of objects   Most likely  you are either passing your class just so the other end can keep track of it and give it back to you later  or you are passing it to a context where a clone can be created from serialized constituent data    or else you are trying to do something that just isn t going to work and you need to rethink the whole approach

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I came across this question when I was looking for a way to pass a Date object  In my case  as was suggested among the answers  I used Bundle putSerializable   but that wouldn t work for a complex thing as the described DataManager in the original post   My suggestion that will give a very similar result to putting said DataManager in the Application or make it a Singleton is to use Dependency Injection and bind the DataManager to a Singleton scope and inject the DataManager wherever it is needed  Not only do you get the benefit of increased testability but you ll also get cleaner code without all of the boiler plate  passing dependencies around between classes and activities  code   Robo Guice is very easy to work with and the new Dagger framework looks promising as well

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The Parcelable interface is a good way to pass an object with an Intent     How can I make my custom objects Parcelable  is a pretty good answer on how to use Parcelable  The official google docs also include an example

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another simple way to pass object using a bundle    in the class object  create a static list or another data structure with a key when you create the object  put it in the list data structure with the key  es  the long timestamp when the object is created  create the method static getObject long key  to get the object from the list in the bundle pass the key  so you can get the object later from another point in the code

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One More way to send objects through bundle is by using bundle putByteArray Sample code  public class DataBean implements Serializable   private Date currentTime   public setDate         currentTime   Calendar getInstance   getTime        public Date getCurrentTime         return currentTime         put Object of DataBean in to Bundle   class FirstClass  public void onCreate Bundle savedInstanceState    super onCreate savedInstanceState     Your code       When you want to start new Activity    Intent dataIntent  new Intent FirstClass this  SecondClass class               Bundle dataBundle new Bundle                DataBean dataObj new DataBean                dataObj setDate                try                   dataBundle putByteArray  Obj byte array   object2Bytes dataObj                   catch  IOException e                       TODO Auto-generated catch block                 e printStackTrace                                dataIntent putExtras dataBundle                startActivity dataIntent       Converting objects to byte arrays         Converting objects to byte arrays     static public byte   object2Bytes  Object o   throws IOException         ByteArrayOutputStream baos   new ByteArrayOutputStream          ObjectOutputStream oos   new ObjectOutputStream  baos          oos writeObject  o          return baos toByteArray            Get Object back from Bundle    class SecondClass  DataBean dataBean  public void onCreate Bundle savedInstanceState    super onCreate savedInstanceState     Your code       Get Info from Bundle        Bundle infoBundle getIntent   getExtras        try           dataBean    DataBean bytes2Object infoBundle getByteArray  Obj byte array           catch  IOException e               TODO Auto-generated catch block         e printStackTrace          catch  ClassNotFoundException e               TODO Auto-generated catch block         e printStackTrace              Method to get objects from byte arrays          Converting byte arrays to objects     static public Object bytes2Object  byte raw             throws IOException  ClassNotFoundException         ByteArrayInputStream bais   new ByteArrayInputStream  raw          ObjectInputStream ois   new ObjectInputStream  bais          Object o   ois readObject          return o          Hope this will help to other buddies

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You can also make your objects Serializable and use the Bundle s getSerializable and putSerializable methods

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This is a very belated answer to my own question  but it keep getting attention  so I feel I must address it  Most of these answers are correct and handle the job perfectly  However  it depends on the needs of the application  This answer will be used to describe two solutions to this problem    Application The first is the Application  as it has been the most spoken about answer here  The application is a good object to place entities that need a reference to a Context  A  ServerSocket  undoubtedly would need a context  for file I o or simple  ListAdapter  updates   I  personally  prefer this route  I like application s  they are useful for context retrieving  because they can be made static and not likely cause a memory leak  and have a simple lifecycle    Service The Service  is second  A  Service is actually the better choice for my problem becuase that is what services are designed to do   A Service is an application component that can perform long-running operations in the background and does not provide a user interface   Services are neat in that they have a more defined lifecycle that is easier to control  Further  if needed  services can run externally of the application  ie  on boot   This can be necessary for some apps or just a neat feature   This wasn t a full description of either  but I left links to the docs for those who want to investigate more  Overall the Service is the better for the instance I needed - running a ServerSocket to my SPP device

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You could use the global application state   Update   Customize and then add this to your AndroidManifest xml     lt application android label   string app name  android debuggable  true  android name   CustomApplication    And then have a class in your project like this    package com example   import android app Application   public class CustomApplication extends Application       public int someVariable   -1      And because  It can be accessed via getApplication   from any Activity or Service   you use it like this   CustomApplication application    CustomApplication getApplication    application someVariable   123     Hope that helps

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1 A very direct and easy to use example  make object to be passed implement Serializable   class Object implements Serializable      String firstName     String lastName      2 pass object in bundle  Bundle bundle   new Bundle    Object Object   new Object    bundle putSerializable  object   object     3 get passed object from bundle as Serializable then cast to Object   Object object    Object  getArguments   getSerializable  object

[android] How to send objects through bundle

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