How to get the same instance of activity in fragments?

Question

Consider the situation: There is mainActivity. Form this activity we can call two fragments: fragmentA and fragmentB.

mainActivity has one getter getValue and one setter setValue.

Most of the time this is how application works: mainActivity is created. From it fragmentA is created. After back button is pressed in fragmentA, application moves back to mainActivity and goes to fragmentB.

What I want to do is, I want to setValue to mainActivity in fragmentA and get that value in fragmentB.

I am not able to do this since it looks like both fragments do not have the same instance of activity.

This is how I try to access setters/getters of mainActivity from fragmentA and fragmentB: ((MainActivity)getContext()).getValue();

What am I doing wrong?

Sounds like this. http://stackoverflow.com/questions/24777985/how-to-implement-onfragmentinteractionlistener — OneCricketeer, Apr 24 '17 at 07:52
@marius what is getValue you are passing to second fragment? — Vinod Pattanshetti, Apr 24 '17 at 07:52
@VinodPattanshetti it is int, other value is BigDecimal (I have more than one) — Marius, Apr 24 '17 at 07:55
@Marius You should [edit] your question to show your actual code — OneCricketeer, Apr 24 '17 at 08:03

score 1 · Answer 1 · answered Apr 24 '17 at 07:46

1

I would recommend using the following method:

((MainActivity) getActivity()).getValue;

Also, make sure that the getValue() method in the MainActivity is set to public.

I hope this helped.

answered Apr 24 '17 at 07:46

Anas Imran Tasadduq

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As much as I know - you should use getActivity for UI related work, getContext for knowing certain states of application. – Marius Apr 24 '17 at 07:47
Well, I use the method I mentioned for sending and receiving data to and from my main activity. Correct me if I misunderstood you. – Anas Imran Tasadduq Apr 24 '17 at 07:50
Coupling your Fragment to any one Activity is a poor design – OneCricketeer Apr 24 '17 at 07:53
@cricket_007 Could you elaborate your point, please? I don't get what you mean by coupling. – Anas Imran Tasadduq Apr 24 '17 at 07:56
A Fragment should never know which specifiic Fragment they are attached to. https://en.wikipedia.org/wiki/Coupling_(computer_programming) – OneCricketeer Apr 24 '17 at 08:01
"You should design each fragment as a modular and reusable activity component" -- Meaning, you should be able to re-use your Fragments in *any activity*... What you have isn't wrong, but there are different ways to do it, that is all – OneCricketeer Apr 24 '17 at 08:03

Akshay More · Accepted Answer · 2017-08-17T07:17:56.297

0

create a Bunde object in Activity

Bundle bundle = new Bundle();

insert values in bundle (can pass multiple values)
key can be any String and should be unique to each value

 bundle.setString(key,"value");

create object of the corresponding Fragment and attach the bundle to it

 fragmentobject.setArguments(bundle);

in the receiving Fragment create Bundle Object

Bundle fragmentbundle = getArguments();
String value = fragmentbundle.getString(key);

this is how you pass value between fragments and activities or activities and activities

edited Aug 17 '17 at 07:17

answered Apr 24 '17 at 07:53

Akshay More

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Sure, this might be the most "correct" way of doing it. However, I also need to pass BigDecimal value and as much as I know, you can't (or you need to convert it to String). – Marius Apr 24 '17 at 07:58
`String value = "1,000,000,000.999999999999999"; BigDecimal money = new BigDecimal(value.replaceAll(",", "")); System.out.println(money);` – Akshay More Apr 24 '17 at 08:10
@Marius `BigDecimal` is `Serializable`. – Kevin Krumwiede Apr 24 '17 at 08:22

How to get the same instance of activity in fragments?

2 Answers2