Re: [android-developers] How to send reference object to a fragment in android studio

2015-12-04 Thread Mark Phillips 
As an alternative, why not store the ArrayList in the Application
object, and have getArrayList and setArrayList methods.
The Fragment can access the ArrayList and update
ArrayList with these methods. Since the Application object is a
singelton, there will only be one valid copy of ArrayList.

Mark

On Fri, Dec 4, 2015 at 1:20 AM, Doug  wrote:

>
>
> On Thursday, December 3, 2015 at 8:03:24 PM UTC-8, TreKing wrote:
>>
>>
>> On Thu, Nov 26, 2015 at 12:35 AM, Vinayak Mestri 
>> wrote:
>>
>>> I want to do like above code i.e student is reference variable so if i
>>> change any values of student arraylist will reflect to actual object in
>>> activity
>>
>>
>> 1 - Look at the documentation for Fragment which shows the static
>> constructor pattern that is typically used to construct a fragment with
>> parameters.
>> http://developer.android.com/reference/android/app/Fragment.html
>> Your model object would implement the Parcelable interface to be passed
>> along as data.
>>
>> 2 - You can then let the Activity know when changes are made via
>> callbacks:
>>
>> http://developer.android.com/guide/components/fragments.html#CommunicatingWithActivity
>>
>> You generally don't want the exact same data object in the activity and
>> fragment.
>>
>
> You generally *do* want the exact same data object if the object is large
> and would take significant time and memory to serialize and deserialize in
> a fully duplicated form.  This is especially OK if your source object is
> immutable and therefore threadsafe and immune to tampering for read
> operations.
>
>
>> If you really really do, you could alternative expose it as a public
>> method in the Activity then instead of passing it to the fragment, access
>> your activity in the fragment (onAttach or onActivityCreated or something)
>> and get the list data, which would be the actual list both objects would
>> share.
>>
>
> Also, if serialization is not a well-performing option, sending the
> fragment an indicator on how to find the collection would be fine.
> Sometimes people use an event bus to publish stored data object to
> dependents.  Sometimes receiving from a singleton is good enough as long as
> it's not adding too much weight to the app.  Sometimes querying a content
> provider (backed by sqlite database) for very large collections is
> appropriate.
>
> Doug
>
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> .
>
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Re: [android-developers] How to send reference object to a fragment in android studio

2015-12-04 Thread Doug 


On Thursday, December 3, 2015 at 8:03:24 PM UTC-8, TreKing wrote:
>
>
> On Thu, Nov 26, 2015 at 12:35 AM, Vinayak Mestri  > wrote:
>
>> I want to do like above code i.e student is reference variable so if i 
>> change any values of student arraylist will reflect to actual object in 
>> activity
>
>
> 1 - Look at the documentation for Fragment which shows the static 
> constructor pattern that is typically used to construct a fragment with 
> parameters.
> http://developer.android.com/reference/android/app/Fragment.html
> Your model object would implement the Parcelable interface to be passed 
> along as data.
>
> 2 - You can then let the Activity know when changes are made via callbacks:
>
> http://developer.android.com/guide/components/fragments.html#CommunicatingWithActivity
>
> You generally don't want the exact same data object in the activity and 
> fragment.
>

You generally *do* want the exact same data object if the object is large 
and would take significant time and memory to serialize and deserialize in 
a fully duplicated form.  This is especially OK if your source object is 
immutable and therefore threadsafe and immune to tampering for read 
operations.
 

> If you really really do, you could alternative expose it as a public 
> method in the Activity then instead of passing it to the fragment, access 
> your activity in the fragment (onAttach or onActivityCreated or something) 
> and get the list data, which would be the actual list both objects would 
> share.
>

Also, if serialization is not a well-performing option, sending the 
fragment an indicator on how to find the collection would be fine.  
Sometimes people use an event bus to publish stored data object to 
dependents.  Sometimes receiving from a singleton is good enough as long as 
it's not adding too much weight to the app.  Sometimes querying a content 
provider (backed by sqlite database) for very large collections is 
appropriate.

Doug

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Re: [android-developers] How to send reference object to a fragment in android studio

2015-12-03 Thread TreKing 
On Thu, Nov 26, 2015 at 12:35 AM, Vinayak Mestri  wrote:

> I want to do like above code i.e student is reference variable so if i
> change any values of student arraylist will reflect to actual object in
> activity


1 - Look at the documentation for Fragment which shows the static
constructor pattern that is typically used to construct a fragment with
parameters.
http://developer.android.com/reference/android/app/Fragment.html
Your model object would implement the Parcelable interface to be passed
along as data.

2 - You can then let the Activity know when changes are made via callbacks:
http://developer.android.com/guide/components/fragments.html#CommunicatingWithActivity

You generally don't want the exact same data object in the activity and
fragment. If you really really do, you could alternative expose it as a
public method in the Activity then instead of passing it to the fragment,
access your activity in the fragment (onAttach or onActivityCreated or
something) and get the list data, which would be the actual list both
objects would share.

-
TreKing  - Chicago
transit tracking app for Android-powered devices

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[android-developers] How to send reference object to a fragment in android studio

2015-11-30 Thread Vinayak Mestri 

I want to send model object (ArraList) to a fragment using 
contructor but new Fragment does not allow to send reference of custom 
model object using constructor.
How can i achieve this.


1. ArrayList student; contains information of students
2. fragment contains UI/Events which can change some properties of selected 
student (e.g Name, age)



class StudentFrament extend Fagment
{

public StudentFragment(Context context;, ArrayList student)
{

}

} 



I want to do like above code i.e student is reference variable so if i 
change any values of student arraylist will reflect to actual object in 
activity

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