如何将变量从活动传递到片段不能解决所有先前的问题

Question

how to pass a variable from ViewSyllabusActivity to fragment tried many examples and many times i want to pass data ViewSyllabusActivity .java to Fragment.java but im unable to send data help me thanks in advance

ViewSyllabusActivity.java

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

        viewPager = (ViewPager) findViewById(R.id.viewpager);
        setupViewPager(viewPager);

        tabLayout = (TabLayout) findViewById(R.id.tabs);
        tabLayout.setupWithViewPager(viewPager);
        setupTabIcons();

        Intent intent = getIntent();
        int sem = intent.getIntExtra(SubListActivity.EXTRA_NUMBER, 0);
        String sid = intent.getStringExtra(SubListActivity.EXTRA_TEXT);

    }
    private void setupViewPager(ViewPager viewPager) {
        ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());

        adapter.addFrag(new ObjFragment(), "Objectives");
        adapter.addFrag(new ContActivity(), "Contents");
        adapter.addFrag(new LaboActivity(), "Laboratory");
        adapter.addFrag(new TBActivity(), "Text Books");
        adapter.addFrag(new LaboActivity(), "References");
        viewPager.setAdapter(adapter);
    }

    class ViewPagerAdapter extends FragmentPagerAdapter {
        private final List<Fragment> mFragmentList = new ArrayList<>();
        private final List<String> mFragmentTitleList = new ArrayList<>();

        public ViewPagerAdapter(FragmentManager manager) {
            super(manager);
        }

        @Override
        public Fragment getItem(int position) {
            return mFragmentList.get(position);
        }

        @Override
        public int getCount() {
            return mFragmentList.size();
        }

        public void addFrag(Fragment fragment, String title) {
            mFragmentList.add(fragment);
            mFragmentTitleList.add(title);
        }

    }

Fragment.java

    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        View view = inflater.inflate(R.layout.fragment_obj, container, false);
        TextView textView = view.findViewById(R.id.obj);
    return view;
    }

Answer 1

Use an EventBus. It's really easy and nice.

1 - Create an event :

public class SendDataToFragmentEvent{
private YourDataType yourData;

 public SendDataToFragmentEvent(YourDataType yourData){ 
  this.yourData = yourData;
 }

 public void getYourData(){return yourData;}

}

And than in your activity , on the moment you want to send data to fragment:

EventBus.getDefault.post(new SendDataToFragmentEvent(yourDataHere));

And than you must wait for this data in the fragment :

@Subscribe(threadMode = ThreadMode.MAIN)  
public void onSendDataToFragmentEvent(SendDataToFragmentEventevent 
 event) {
/* Do something with your data here*/
};

Don't forget the EventBus must know when to start listening or stop :

 @Override
 public void onStart() {
    super.onStart();
    EventBus.getDefault().register(this);
 }

 @Override
 public void onStop() {
   super.onStop();
   EventBus.getDefault().unregister(this);
 }

This is because Eventbus stays here forever untill your fragment/activity is destroyed .

Note : The fragment must be open to listen from the activity your event .

Here is the link to that library , I found it really nice.

Answer 2

you have send some values in ViewPagerAdapter Like this:-

@Override
public Fragment getItem(int position) {
    Bundle bundle = new Bundle();
    if(position == 0){
        bundle.putInt("position", position);
        bundle.putString("survayType", "your value");
        mFragmentList.get(position).setArguments(bundle);
    }else if(position == 1){
        bundle.putInt("position", position);
        bundle.putString("survayType", "your value");
        mFragmentList.get(position).setArguments(bundle);
    }else if(position == 2){
        bundle.putInt("position", position);
        bundle.putString("survayType", "your value");
        mFragmentList.get(position).setArguments(bundle);
    }else if(position == 3){
        bundle.putInt("position", position);
        bundle.putString("survayType", "your value");
        mFragmentList.get(position).setArguments(bundle);
    }else if(position == 4){
        bundle.putInt("position", position);
        bundle.putString("survayType", "your value");
        mFragmentList.get(position).setArguments(bundle);
    }

    return mFragmentList.get(position);
}

and get values in fragment like this:-

String survayType = getArguments().getString("survayType");

i do this and it is working for me.