Data Sharing between Fragments and Activity in Android

Question

Ive asked a similar question before and didn't get an answer and seems many other ppl are searching for an answer. So I am posting this question to hopefully get a clear answer that everyone can benefit from.

I have an activity with 2 fragments in it. I want fragment2 to set a boolean variable in Activity when a checkbox is checked so that fragment1 can know if the checkbox was checked.

This is my Code:

Activity:

public class modestab extends Activity{ public static Context appContext; public boolean lf=false; public void onCreate(Bundle savedInstanceState){ appContext=this; super.onCreate(savedInstanceState); ActionBar tabbar= getActionBar(); tabbar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS); ActionBar.Tab ModesTab =tabbar.newTab().setText("Modes"); ActionBar.Tab CatTab =tabbar.newTab().setText("Categories"); Fragment ModesFragment =new modes(); Fragment CatFragment =new cats(); ModesTab.setTabListener(new MyTabsListener(ModesFragment)); CattTab.setTabListener(new MyTabsListener(CatFragment)); tabbar.addTab(ModesTab); tabbar.addTab(CatTab); }

Fragment 1:(Where I want to read the boolean lf set in Acitivity above:

@TargetApi(11) public class tabmodes extends Fragment{ @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View V=inflater.inflate(R.layout.tab_modes, container, false); button1.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub if(lf==false) //lf here is the lf in Activity which I want to get

Fragment 2: Where I want to set lf in Activity

..... lifecheck.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener(){ @Override public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) { if(lifecheck.isChecked()) getActivity().lf=true;//Where I want to set the lf flag in Activity ; } });

The code doesn't compile and I am not knowing how to set lf in the Activity nor how to read it. Someone suggested I do getActivity() but I am not able to see the variable.

I tried to create a function setlf(boolean jk) but also I am not able to see it...

Any help is welcome :)

Roses · Accepted Answer · 2017-09-21 14:23:49Z

Many ways :

1) Activity -> Fragment

In your Activity : create a bundle and use fragment.setArguments(bundle)
in your Fragment : use Bundle bundle = getArguments()

2) Activity -> Fragment

In your Fragment : create a public method
In your Activity : call an active fragment public method :

getSupportFragmentManager().findFragmentById(R.id.your_fragment).publicMethod(args)

3) Fragment -> Activity

In your Fragment : create un interface with getter and setter methods (callback methods)
In your Activity : implement the interface

4) Fragment -> Activity

In your Activity : Create public getter and setter or other methods
In your Fragment : called public activity getter, setter or other methods using :

getActivity().getSomething(), getActivity().setSomething(args) or getActivity().someMethod(args)

You just solved a big problem for me and saved me a whole bunch of work. Thanks!
why is it bad to use a static variable . and cant we use a static object instead of static methods and variables
Nicely written answer with multiple options really helps. I'm wondering about the trade-offs of each (are there benefits or negatives to each? - or are they all basically equal?) and are these still the 4 main ways in the present (2019) since this answer is 6 years old? Just curious.

RajeshVijayakumar · Accepted Answer · 2012-11-18 23:43:59Z

2

You can pass data between fragments in two ways,

First, you can do it by using setArguments(...) and getArguments(....)

Second,you can do it using Call back

answered Nov 18, 2012 at 23:43

RajeshVijayakumar

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4 Comments

Syntax_Error Over a year ago

Is this the only way to share data by passing arguments between the fragments? can't I set and get the variables in the activity directly?

RajeshVijayakumar Over a year ago

Otherwise you can use sharedpreferences for data sharing

Nicholas TJ Over a year ago

I'm pretty new to this, do you have any example on the setArguments and getArguments

Ojonugwa Jude Ochalifu Over a year ago

For a question that specifically asks for clear answers, yours doesn't help much.

Mete · Accepted Answer · 2016-01-18 11:47:19Z

Also you can use EventBus. It's really simple. https://github.com/greenrobot/EventBus

Definitely don't use static methods like my old answer :)

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