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 :)

Answer 1

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)