Java-Send data from activity to tab fragment in Android Studio

Question

I am new to Java. The activity is to receive an ID and reuse that ID to get the detail of the recipe with a Recipe API. I am using three tabs to show different content. The problem that I could not figure out is that the first (description tab) and the third (step tab) can receive the string from main activity, but the second tab (ingredient tab) always receives null value from the main activity. Also, The string does not show on the first tab immediately when I run the activity. It only shows after I click on the third tab and come back to the first one.

Activity

public class SearchHomeResultActivity extends AppCompatActivity {


private SectionsPagerAdapter mSectionsPagerAdapter;
private ViewPager mViewPager;
public String RecipeId = "479101";
public String SInstruction;
public String SIngredients;
public String STitle;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_search_result);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
    // Set up the ViewPager with the sections adapter.
    mViewPager = (ViewPager) findViewById(R.id.container);
    mViewPager.setAdapter(mSectionsPagerAdapter);

    TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);

    mViewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
    tabLayout.addOnTabSelectedListener(new TabLayout.ViewPagerOnTabSelectedListener(mViewPager));
    new CallMashapeAsync().execute(RecipeId);
}

public class CallMashapeAsync extends AsyncTask<String, Integer, HttpResponse<JsonNode>> {

    protected HttpResponse<JsonNode> doInBackground(String... msg) {


        HttpResponse<JsonNode> request = null;
        try {
            request = Unirest.get("https://spoonacular-recipe-food-nutrition-v1.p.mashape.com/recipes/" + msg[0] + "/information")
                    .header("X-Mashape-Key", "EulyPgSat2mshhTi8JJxY40UEWzdp1mMmEGjsnrbQq1AB0vuOY")
                    .header("X-Mashape-Host", "spoonacular-recipe-food-nutrition-v1.p.mashape.com")
                    .asJson();
        } catch (UnirestException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        return request;
    }

    protected void onProgressUpdate(Integer... integers) {
    }

    protected void onPostExecute(HttpResponse<JsonNode> response) {
        String answer = response.getBody().toString();
        try {//get all response
            JSONObject obj = new JSONObject(answer);
            //get ingredients
            String Ringredient = obj.getString("extendedIngredients");
            List<String> terms1 = new ArrayList<String>();
            JSONArray ing = new JSONArray(Ringredient);
            for (int i = 0; i < ing.length(); i++) {
                JSONObject ING1 = ing.getJSONObject(i);
                String Ostr = ING1.getString("originalString");
                terms1.add(Ostr);
            }
            String listString = "";
            for (String s : terms1) {
                listString += s + "\n";
            }
            //get instructions
            String Rid1 = obj.getString("instructions");
            //get title
            String Rid2 = obj.getString("title");
            SInstruction = Rid1;
            SIngredients = listString;
            STitle = Rid2;
        } catch (JSONException e) {
            throw new RuntimeException(e);
        }


    }
}

public String getIns() {
    //
    return SInstruction;
}

public String getIngredients() {
    //
    return SIngredients;
}

public String getRTitle() {
    //
    return STitle;
}

public class SectionsPagerAdapter extends FragmentPagerAdapter {

    public SectionsPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int position) {
        switch (position) {
            case 0:
                descriptionTab tab1 = new descriptionTab();
                return tab1;
            case 1:
                IngredientsTabActivity tab2 = new IngredientsTabActivity();
                return tab2;
            case 2:
                StepTabActivity tab3 = new StepTabActivity();
                return tab3;
        }
        return null;
    }

    @Override
    public int getCount() {
        // Show 3 total pages.
        return 3;
    }
}

}

Fragment

public class StepTabActivity extends Fragment {
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState){
    View rootView = inflater.inflate(R.layout.step_layout, container, false);
    SearchHomeResultActivity getData = (SearchHomeResultActivity) getActivity();
    String Rid = getData.getIngredients();
    TextView txt = rootView.findViewById(R.id.name);
    txt.setText(Rid);
    return rootView;



}

This is the code of the Step (the third) fragment. Other two are the same, but just calling different methods to get different strings for the TextView. Please help me. Thank you so much!

Answer 1

You can create a constructor like method called newInstance in your fragment as below,

public static FragmentName newInstance(String str) {
    Bundle args = new Bundle();
    FragmentName fragment = new FragmentName();
    fragment.setArguments(args);
    resID = str;
    return fragment;
}

define your "resID" as global variable and use it in fragment's onCreate method.

and from activity when u are adding fragment to viewPager adapter do like this

adapter.addFrag(FragmentName.newInstance(resID), "fragment_name");