在活动中向另一个发送值时获取片段为null

Question

嗨在我的应用程序中有片段通过接口传递一个值传递给另一个片段，但在我的主片段中声明第二个片段时它显示为空。

MainActivity：

public class MainActivity extends AppCompatActivity
        implements NavigationView.OnNavigationItemSelectedListener,Receive {

    private static final int INTRO_SCREEN = 200;
    MainScreen mainScreen;
    private static final String TAG = MainScreen.class.getName();
    private MyAdapter mPagerAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        drawer.setDrawerListener(toggle);
        toggle.syncState();

        NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);

        Boolean isFirstRun = getSharedPreferences("PREFERENCE", MODE_PRIVATE)
                .getBoolean("isFirstRun", true);
        if (isFirstRun) {
            //show start activity
            Log.d(TAG,"isFirstTime");

            startDefaultIntro();
        }
        getSharedPreferences("PREFERENCE", MODE_PRIVATE).edit()
                .putBoolean("isFirstRun", false).commit();

        ViewPager viewPager = (ViewPager)findViewById(R.id.pager);
        FragmentManager fm = getSupportFragmentManager();
        mPagerAdapter = new MyAdapter(fm);
        viewPager.setAdapter(mPagerAdapter);

    }

    private void showAlertDialog(){
        InputFragment ip = new InputFragment();
        ip.show(getSupportFragmentManager(),"inp");
    }

    @Override
    public void onBackPressed() {
        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        if (drawer.isDrawerOpen(GravityCompat.START)) {
            drawer.closeDrawer(GravityCompat.START);
        } else {
            super.onBackPressed();
        }
    }

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

    @Override
    public void onDataReceive(double result) {
        mainScreen.getData(result);             //here its the transferring data to other fragment but its showing mainScreen null
    }

    private class MyAdapter extends FragmentPagerAdapter {

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

        @Override
        public Fragment getItem(int i) {
            Fragment fragment = null;
            if (i == 0){
                fragment = new MainScreen();
            }
            if (i == 1){
                fragment = new Consumption();
            }
            return fragment;
        }

        @Override
        public int getCount() {
            return 2;
        }
    }

    public void startDefaultIntro(){
        Intent intent = new Intent(this, MyIntro.class);
        startActivityForResult(intent,INTRO_SCREEN);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        Log.d(TAG,"onActivityResult() resultCode:"+resultCode+" requestCode:"+requestCode);
        if(resultCode == RESULT_OK){
            showAlertDialog();

        }
    }
}