How to get data from fragments in the parent activity?

Question

This is my Parent Activity containing a tab layout and view pager and a button at the bottom:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".module.addcontact.AddContactActivity">

    <com.google.android.material.appbar.AppBarLayout
        android:layout_height="wrap_content"
        android:layout_width="match_parent"
        android:theme="@style/AppTheme.PopupOverlay">

        <com.google.android.material.tabs.TabLayout
            android:id="@+id/tabs"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:tabTextColor="@color/colorDarkBlue"
            app:tabSelectedTextColor="@color/colorDarkBlue"
            android:background="@color/white"/>
    </com.google.android.material.appbar.AppBarLayout>

    <androidx.viewpager.widget.ViewPager
        android:id="@+id/view_pager"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        app:layout_behavior="@string/appbar_scrolling_view_behavior" />

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/save"
        android:text="SAVE"
        android:textSize="16sp"
        android:textStyle="bold"
        android:textColor="@color/white"
        android:layout_margin="10dp"
        android:background="@color/colorDarkBlue"/>

</LinearLayout>

Fragments 1:

<?xml version="1.0" encoding="utf-8"?>
<ScrollView
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:gravity="center_horizontal"
    android:fillViewport="true"
    android:padding="@dimen/add_contacts_padding"
    tools:context=".module.addcompany.AddCompanyFragment">

    <TableLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:stretchColumns="1">

    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/name"
        android:hint="Name"
        android:textSize="24sp"
        android:padding="10dp"
        android:layout_marginBottom="10dp"
        android:background="@drawable/edit_text_border"/>

    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/phone"
        android:hint="Phone"
        android:inputType="phone"
        android:textSize="24sp"
        android:padding="10dp"
        android:layout_marginBottom="10dp"
        android:background="@drawable/edit_text_border"/>

    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/address"
        android:hint="Address"
        android:textSize="24sp"
        android:padding="10dp"
        android:layout_marginBottom="10dp"
        android:background="@drawable/edit_text_border"/>

    </TableLayout>

</ScrollView>

Fragment 2 is similar to fragment 1 (with different edit texts e.g. designation and email)

When save button in my parent activity gets pressed, I want to get all the data from both of these fragments in parent activity and if some field is missing then i want to set error to that field.

How can i get data from fragments to the parent activity? Or Is there some way that i can get all the edit texts (fields) of the fragments in the parent activity?

Answer 1

As per your requirement you have to create you have parent activity that means your fragments are loaded using viewpager so you have the instance of each fragment.

Now while you click the button from activity, to check the validation of individual fragment and accessing data you can do this.

First check that which fragment is on which position which will be the position from onPageSelected method of view pager.

Now suppose you have Fragment1 and you want to access data and validate it. Use,

Fragment1 f1= (Fragment1) viewPager
                .getAdapter()
                .instantiateItem(viewPager, position);

Now you need to create validate() method in Fragment1 so you can access that method by,

f1.validate();

Before you call f1.validate(); check that if(f1!=null) && f1.isVisible() and then access data from it and do same for Fragment2.

Answer 2

To allow a Fragment to communicate up to its Activity, you can define an interface in the Fragment class and implement it within the Activity.

Here is an example of Fragment to Activity communication:

public class HeadlinesFragment extends ListFragment {
    OnHeadlineSelectedListener callback;

    public void setOnHeadlineSelectedListener(OnHeadlineSelectedListener callback) {
        this.callback = callback;
    }

    // This interface can be implemented by the Activity, parent Fragment,
    // or a separate test implementation.
    public interface OnHeadlineSelectedListener {
        public void onArticleSelected(int position);
    }

    // ...
}

MainActivity

public static class MainActivity extends Activity
        implements HeadlinesFragment.OnHeadlineSelectedListener{


    @Override
    public void onAttachFragment(Fragment fragment) {
        if (fragment instanceof HeadlinesFragment) {
            HeadlinesFragment headlinesFragment = (HeadlinesFragment) fragment;
            headlinesFragment.setOnHeadlineSelectedListener(this);
        }
    }
}

For example, the following method in the fragment is called when the user clicks on a list item. The fragment uses the callback interface to deliver the event to the parent activity.

@Override
public void onListItemClick(ListView l, View v, int position, long id) {
    // Send the event to the host activity
    callback.onArticleSelected(position);
}

Hope it works for you.