Send data From Activity to Tab Fragment

Question

i have a lite problem with my code, i was search in this site but still not found the best answer i will send data to my tab fragment, this my code

My Activity class

public class MainActivity extends AppCompatActivity 

    private ViewPager pager;
    private Toolbar toolbar;
    private TabLayout tabs;

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


        pager=(ViewPager) findViewById(R.id.pager);
        tabs=(TabLayout) findViewById(R.id.tabs);

        pager.setAdapter(new TabFragmentPagerAdapter(getSupportFragmentManager()));
        tabs.setupWithViewPager(pager);
        tabs.setTabGravity(TabLayout.GRAVITY_FILL);

        Bundle bundle = new Bundle();
        bundle.putString("edttext", "data From Activity");
        // set Fragmentclass Arguments
        tab1Fragment fragobj = new tab1Fragment();
        fragobj.setArguments(bundle);

    }
}

and this my tab1 class

public class tab1Fragment extends Fragment 

    public tab1Fragment() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment

        View view= inflater.inflate(R.layout.fragment_tab1, container, false);
        TextView tes=(TextView) view.findViewById(R.id.testtab1);
        String strtext = getArguments().getString("edttext");

        tes.setText("tes :"+ strtext);
        return  view;
    }
}

and this my page fragment adapter

public class TabFragmentPagerAdapter extends FragmentPagerAdapter 

    String[] title = new String[]{
            "Tab 1", "Tab 2", "Tab 3"
    };

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

    @Override
    public Fragment getItem(int position){
        Fragment fragment=null;
        switch (position){
            case 0:
                fragment=new tab1Fragment();
                break;
            case 1:
                fragment=new tab2Fragment();
                break;
            case 2:
                fragment=new tab3Fragment();
                break;
            default:
                fragment=null;
                break;
        }
        return  fragment;
    }
    @Override
    public  CharSequence getPageTitle(int position){
        return  title[position];
    }
    @Override
    public  int getCount(){
        return  title.length;
    }
}

when i run error

java.lang.NullPointerException

Please Help

Answer 1

In your AppCompatActivity you have send

tab1Fragment fragobj = new tab1Fragment();
fragobj.setArguments(bundle);

but in your TabFragmentPagerAdapter

fragment=new tab1Fragment();
            break;

it has null arguments

inside switch

switch (position){
    case 0:
      fragment=new tab1Fragment();               
      Bundle bundle = new Bundle();
      bundle.putString("edttext", "data From Activity");
      fragment.setArguments(bundle);
    break;

Answer 2

May be you are getting NullPointerException because your fragment getting initialised again inside getItem without argument.

Try this way.

@Override
public Fragment getItem(int position){
    Fragment fragment=null;

    Bundle bundle = new Bundle();
    bundle.putString("edttext", "data From Activity");

    switch (position){
        case 0:
            fragment=new tab1Fragment();
            fragment.setArguments(bundle);
            break;
        case 1:
            fragment=new tab2Fragment();
            break;
        case 2:
            fragment=new tab3Fragment();
            break;
        default:
            fragment=null;
            break;
    }
    return  fragment;
}

Note : make sure you are importing same versions of Fragment in both MainActivity and tab1Fragment.

Answer 3

I think You Start the Tab1Frament() with On call of Youractivity first You can do it...

Used this..

   if (savedInstanceState == null) {

 FragmentTransaction ft = this.getSupportFragmentManager().beginTransaction();

tab1Fragment fragobj = new tab1Fragment();

  Bundle bundle = new Bundle();
  bundle.putString("edttext", "data From Activity");
 // set Fragmentclass Arguments

 fragobj.setArguments(bundle);


    ft.replace(R.id.frame, fragobj);
    ft.addToBackStack(null);
    ft.commit();
  }

Instead of

 Bundle bundle = new Bundle();
 bundle.putString("edttext", "data From Activity");
 // set Fragmentclass Arguments
 tab1Fragment fragobj = new tab1Fragment();
 fragobj.setArguments(bundle);

Answer 4

Create a function in the fragment to pass in the data from activity just like you do in getters and setters for object classes like so:

// Fragment
class TabFragment extends Fragment{

    public String myDataString;

    ...

    public void setTabInfo(String myActivityString){
        this.myDataString = myActivityString;
    }
}

// Activity

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

    ...

    TabFragment frag = new TabFragment();
    frag.setTabInfo("data From Activity");

}

I prefer this method since you pass the data directly without having to serialize the object in the case of using Bundle in the case of objects

Answer 5

Maybe its late answer, but there is something that worked for me:

send your bundle to adapter:

  Bundle bundle = new Bundle();
  bundle.putString("edttext", "data From Activity");
  pager.setAdapter(new TabFragmentPagerAdapter(getSupportFragmentManager(), bundle));

extend a constructor in your adapter:

Bundle bundle;

  public TabFragmentPagerAdapter(FragmentManager fm, Bundle bundle) {
    super(fm);
    this.bundle=bundle;
}

and send it to the fragment:

switch (position){
        case 0:
            fragment=new tab1Fragment();
            fragment.setArguments(bundle);
            break;

hopefully, it helps. }