Develop Reference

Android Parcelable: reading and writing

I want to make a custom entity class Parcelable.. I have some fields in it: a String[] and another custom entity object (which is parcelable).. I want to know how to read and write these objects and lists..
public class CustomEntity implements Parcelable {
private int number;
private String[] urls;
private AnotherEntity object;
public CustomEntity(Parcel in) {
number = in.readInt();
// how should I read urls?
// how should I read object?
}
#Override
public void writeToParcel(Parcel parcel, int i) {
parcel.writeInt(number);
// how should I write urls?
// how should I write object?
}
}

For a String[] you can use the API
parcel.writeStringArray(url)
For AnotherEntity you need to extend it with Parcelable again
parcel.writeParcelable();

https://github.com/mcharmas/android-parcelable-intellij-plugin use this plugin!
Your AnotherEntity must implemented Parcelable too!

I definitely think you should NOT handle the boilerplate yourself.
There are libraries around like Parceler where with only one annotation on your POJO and one line like Parcel.wrap or Parcel.unwrap you can do instant serialization.

Haxe: How can I setup a class to store data in an array of type that I pass in the constructor

I am coding in Haxe, Lime, OpenFl. I am trying to set up a Class to store data in a Map, referenced by class instance. The class type is to be passed in the constructor, via inference. But I am quite new to all this and can't quite figure out the syntax, this is what I got so far:
class DynamicStore<A>
{
private var hashA:Map<Class<A>,String>;
public function new<A>(paramA:Class<A>) {
hashA = new Map();
}
}
But this gives me the following error:
Abstract Map has no #:to function that accepts IMap<Class<DynamicStore.A>, String>
Is there a way to do this?

A question first:
do you really want to use classes as key? or objects?
In classes should be the key
It would be much simpler to use the classe's full name as key, like "mypackage.blob.MyClass". It's safer, easier to handle and debug.
Map<String, String>
Would suffice in that case.
If objects should be keys
Then the code would look like:
import haxe.ds.ObjectMap;
class Test<A>
{
static function main() {}
private var hashA :ObjectMap<A,String>;
public function new(paramA:A) {
hashA = new ObjectMap<A,String>();
}
}
The reason "Map" cannot be directly used in this case is that "Map" is a syntactic sugar, being resolved to StringMap, IntMap or others depending on the key type. If it doesn't know what kind of map to be used, it cannot proceed (this is mainly due to cross-compiling issues).
Remark
As a final note, I would mention your construction seems a bit wacky/strange to me. It would be interesting to know what you are trying to achieve and why you structure it the way you do.

I don't think you can use Class as the key of a Map. A good work around it to use a String as a key and the fully qualified names of the types. You can also define an abstract to move from the Type to String easily ... something like the following (code not-tested);
private var hashA : Map<String, String>;
public function addClass(className : ClassId, ...)
And the abstract will look something like this:
abstract ClassId(String) {
inline public function new(name : String) this = name;
#:from public static inline function fromClass(cls : Class<Dynamic>)
return new ClassId(Type.getClassName(cls));
#:to public inline function toClass() : Class<Dynamic>
return Type.resolveClass(this);
#:to public inline function toString() : String
return this;
}

Pass the arraylist from one activity to another

I am trying to pass the complete arraylist from one activity to another.
i have tried like this way..
arraylist=new ArrayList<HashMap<String,Object>>();
Intent i= new Intent(ListActivity.this,search.class);
i.putExtra("arraylist", arraylist);
startActivity(i);
Could somebody help me out #thanks

This will not work because the Object class in Java is not serializable. See this question for an explanation as to why.
The Intent.putExtra() method requires a type that implements the serializable interface, Object does not implement this so consequently it will not work. I would suggest rather than having a HashMap<String,Object> you replace the Object with a more specific type that implements the Serializable interface. See this tutorial for how to do this.
UPDATE
If the data you are passing is large there could be a fairly significant overhead associated with serializing and deserializing. Consequently it might be worth using a Static Singleton class to store the arraylist. The code sample below shows how you could implement this:
public class DataStore {
private static final DataStore instance = new DataStore ();
private arraylist = new ArrayList<HashMap<String,Object>>();
//Private constructor
private DataStore () {}
//Class is only accessible through this method
public static Singleton getInstance() {
return instance;
}
//Accessors for your data
private ArrayList<HashMap<String,Object>> getArrayList()
{
return arraylist;
}
private void setArrayList(ArrayList<HashMap<String,Object>> value)
{
arraylist = value;
}
}
For reference here is a tutorial on static singletons.

Is it possible to send a custom object with an Intent as an Extra

I'm asking this question: instread of giving a string, a int and so on, can we push a custom object during the creation fo a new Intent?
newActivity.PutExtra("JsonDataResult", business.getJSON());
In fact I have one object constructed thanks to a JSON (from webrequest) , I parse it and I put it on an object.
At this point I'm passing the string returned from the webrequest to another intent but the parsing takes a long time tu be done, so it could be super-cool the ability to pass custom object with intent.
EDIT : I'm using monodroid / xamarin, so
Android.OS.IParcelable cannot be implemented,
Java.IO.ISerializable cannot be implemented.

You can either let your custom classes implement Parcelable (Google says its faster, but you have to do more coding) or Serializable.
Then add your objects to a bundle (or to the "extra"):
Bundle b = new Bundle()
b.putParcelable("myObject",myObject);
b.putSerializable("myObject",myObject);
For info to Parcelablecheckout this
And if you're interested in the difference between Parcelable and Serializable in more detail check out this
I personally prefer the usage of Serializable for simple object-passing, since the code ist not spoiled with so much code.
Edit: ok isn't your question very similar to this then?

As you've specified you're using Monodroid, it looks like it's not straightforward. I did a quick search and found this forum post
Which listed the following solutions to this problem in Monodroid:
Store the custom Object to be passed as a global variable somewhere, and just read it from your second activity
Which is a bit messy and bad practice, but would work.
Or
serialize your class to a string and send the string to the second Activity
Which will be a little more hard work, but better practice

This is an example how to create a Parcelable class:
public class Person implements Parcelable {
private String name;
private String surname;
private String email;
// Get and Set methods
#Override
public int describeContents() {
return hashCode();
}
#Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeString(name);
dest.writeString(surname);
dest.writeString(email);
}
// We reconstruct the object reading from the Parcel data
public Person(Parcel p) {
name = p.readString();
surname = p.readString();
email = p.readString();
}
public Person() {}
// We need to add a Creator
public static final Parcelable.Creator<person> CREATOR = new Parcelable.Creator<person>() {
#Override
public Person createFromParcel(Parcel parcel) {
return new Person(parcel);
}
#Override
public Person[] newArray(int size) {
return new Person[size];
}
};
Give a look here if you want to use Parcelable.

android pass ArrayList<self_Obj> by Intent

I had create a class named ChannelObj that contains values like this
public class ChannelObj {
public String enable;
public String id;
public String name;
public String ptz;
public ChannelObj(Node n){
this.enable = n.getAttributes().getNamedItem("enabled").getNodeValue();
this.id = n.getAttributes().getNamedItem("id").getNodeValue();
this.name = n.getAttributes().getNamedItem("name").getNodeValue();
this.ptz = n.getAttributes().getNamedItem("ptz").getNodeValue();
}
}
and this Class can create Obj that contains what data I need;
after that,I have an ArrayList named allChannel contains all ChannelObj i have
like this
for(int i = 0;i<num_of_channel;i++)
{
allChannel.add(new ChannelObj(n1.item(i)));
}
i've checked the data in allChannel is correct
but i want pass this ArrayList to next Activity
i've tried ways like
Intent i = new Intent(this,ChannelListActivity.class);
Bundle b = new Bundle();
b.putParcelableArrayListExtra("dd", ArrayList<ChannelObj> allChannels);
i.putExtra(String name,b);
startActivity(i);
but didn't work and still wrong
what i suppose to do?
thanks for your help!

An alternative to the answer given by Benoir is to have your ChannelObj class implement the Serializable interface. You're only using simple data types, so all the (de)serializing will be automa(g)(t)ically done underwater.
If your class implements Serializable, then you can add it to a Bundle as follows:
bundle.putSerializable("CHANNELOBJ_LIST", mChannelObjList);
Note that you may need to cast to an ArrayList<ChannelObj> (or some other concrete implementation of List<T>) as the List<T> interface does not implement Serializable.
Retrieving the list of objects in the next activity is similarly easy:
List<ChannelObj> mChannelObjList = (ArrayList<ChannelObj>) bundle.getSerializable("CHANNELOBJ_LIST");

Your clas must implement Parcelable check it out here: http://developer.android.com/reference/android/os/Parcelable.html