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name Punditsdkoslkdosdkoskdo

Data Sharing between Fragments and Activity in Android

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:


public class modestab extends Activity{
    public static Context appContext;

    public boolean lf=false;

    public void onCreate(Bundle savedInstanceState){
ActionBar tabbar= getActionBar();
        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));



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

public class tabmodes extends Fragment{
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
View V=inflater.inflate(R.layout.tab_modes, container, false);
button1.setOnClickListener(new View.OnClickListener() {

            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(){
                public void onCheckedChanged(CompoundButton buttonView,
                        boolean 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 :)

Many ways :

1) Activity -> Fragment

2) Activity -> Fragment

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)

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    • why is it bad to use a static variable . and cant we use a static object instead of static methods and variables
      • 2
    • 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.

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

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