Android - Using Android Studio default ViewPager setup to pass data between an Activity and Fragment

Question

I am looking into passing data between an Activity (ActionBarActivity) to a Fragment. Currently, I am testing using the generated code from Android Studio (only thing added is the TextView showing the fragment number).

I've seen answer pointing to using a bundle, however it would not seem to work in this case as the bundle is created within the fragment itself rather than the parent Activity. In this scenario, with the default implementation, how would you pass the data. Alternatively, without straying too far away from the base, what would be an alternative?

MainActivity.java (contains the activity, adapter and demo fragment)

package com.blah.fragmentswitchingtest;

import java.util.Locale;

import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.app.FragmentPagerAdapter;
import android.os.Bundle;
import android.support.v4.view.ViewPager;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;


public class MainActivity extends ActionBarActivity {

    /**
     * The {@link android.support.v4.view.PagerAdapter} that will provide
     * fragments for each of the sections. We use a
     * {@link FragmentPagerAdapter} derivative, which will keep every
     * loaded fragment in memory. If this becomes too memory intensive, it
     * may be best to switch to a
     * {@link android.support.v4.app.FragmentStatePagerAdapter}.
     */
    SectionsPagerAdapter mSectionsPagerAdapter;

    /**
     * The {@link ViewPager} that will host the section contents.
     */
    ViewPager mViewPager;
    public String stringToCarry = "String"; // How would I carry this string to into the Fragment

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        // Create the adapter that will return a fragment for each of the three
        // primary sections of the activity.
        mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());

        // Set up the ViewPager with the sections adapter.
        mViewPager = (ViewPager) findViewById(R.id.pager);
        mViewPager.setAdapter(mSectionsPagerAdapter);

    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }


    /**
     * A {@link FragmentPagerAdapter} that returns a fragment corresponding to
     * one of the sections/tabs/pages.
     */
    public class SectionsPagerAdapter extends FragmentPagerAdapter {

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

        @Override
        public Fragment getItem(int position) {
            // getItem is called to instantiate the fragment for the given page.
            // Return a PlaceholderFragment (defined as a static inner class below).
            return PlaceholderFragment.newInstance(position + 1);
        }

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

        @Override
        public CharSequence getPageTitle(int position) {
            Locale l = Locale.getDefault();
            switch (position) {
                case 0:
                    return getString(R.string.title_section1).toUpperCase(l);
                case 1:
                    return getString(R.string.title_section2).toUpperCase(l);
                case 2:
                    return getString(R.string.title_section3).toUpperCase(l);
            }
            return null;
        }
    }

    /**
     * A placeholder fragment containing a simple view.
     */
    public static class PlaceholderFragment extends Fragment {

        protected TextView mSectionLabel;
        /**
         * The fragment argument representing the section number for this
         * fragment.
         */
        private static final String ARG_SECTION_NUMBER = "section_number";

        /**
         * Returns a new instance of this fragment for the given section
         * number.
         */
        public static PlaceholderFragment newInstance(int sectionNumber) {
            PlaceholderFragment fragment = new PlaceholderFragment();
            Bundle args = new Bundle();
            args.putInt(ARG_SECTION_NUMBER, sectionNumber);
            fragment.setArguments(args);
            return fragment;
        }

        public PlaceholderFragment() {
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.fragment_main, container, false);

            mSectionLabel = (TextView)rootView.findViewById(R.id.section_label);


            Integer myValue = this.getArguments().getInt(ARG_SECTION_NUMBER);
            String blah = myValue.toString();

            mSectionLabel.setText(blah);

            return rootView;
        }
    }

}

Answer 1

hi an easy solution is to create a public static class in the main activity and access its properties from the fragments

Another is to implement callbacks

For example in the main activity you create a static class like so :

public static class MyData{

String mName;
String mSurname;

public MyData(String mName, String mSurname) {
    this.mName = mName;
    this.mSurname = mSurname;
}


public String getmName() {
    return mName;
}


public String getmSurname() {
    return mSurname;
}

}

Also in the Main Activity we have a public static Array holding data items :

public static ArrayList<MyData>mData = new ArrayList<>();

In the OnCreate Main Activity we populate the data :

mData.add(new MyData("John","Doe"));
mData.add(new MyData("Peter","Pan"));

From the fragments we can access data like so :

ArrayList<MainActivity.MyData>list = MainActivity.mData;

for(MainActivity.MyData obj : list){
    Log.d("DATA", obj.getmName() + " " + obj.getmSurname());

}