从活动获取变量的值并将其传递给片段活动

Question

I want to get the value of mLocal in my Activity and pass it to LatLng on Fragment class.

Main Activity

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

            initLocationFetching(MainActivity.this);

        mapFragment = new MapFragment(MainActivity.this, this);
        manager = getSupportFragmentManager();
        manager.beginTransaction().replace(R.id.mainLayout, mapFragment).commit();
}
            @Override
        public void locationFetched(Location mLocal, Location oldLocation, String time, String locationProvider) {
        super.locationFetched(mLocal, oldLocation, time, locationProvider);
    > here mLocal
    }

Map Fragment Class

 class MapFragment extends Fragment implements OnMapReadyCallback,
            GoogleApiClient.OnConnectionFailedListener {

    @Override
    public void onMapReady(GoogleMap googleMap) {
        mMap = googleMap;

        LatLng origin = new LatLng(14.507328, 121.000905);

        mMap.addMarker(new MarkerOptions()
                .position(new LatLng(14.507577, 121.004456))
                .anchor(0.5f, 0.5f)
                .title("title")
                .snippet("snippet")
                .icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_CYAN)));

        mMap.animateCamera(CameraUpdateFactory.newLatLngZoom(new LatLng(value1, value2), 9.0f));

    }

Above, I want it not hardcoded. I want to get the value of mLocal in MainActivity and pass it on LatLng() MapFragment.

Answer 1

you can take a public global vaiable of Location in activity and create it's getter-setter

 


 MainActivity extends Activity

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

            @Override
        public void locationFetched(Location mLocal, Location oldLocation, String time, String locationProvider) {
        super.locationFetched(mLocal, oldLocation, time, locationProvider);
    setMLocal(mLocal);
    } 
     public String getMLocal() {
            return mLocal;
        }

        public void setMLocal(String mLocal) {
            this.mLocal= mLocal;
        }

And then you can use getter method in your fragment

public void onMapReady(GoogleMap googleMap) {
        mMap = googleMap;
    Location mLocal = ((MainActivity)getActivity).getMLocal(); //you can get your Location object and you can use it further
        //LatLng origin = new LatLng(14.507328, 121.000905);

        mMap.addMarker(new MarkerOptions()
                .position(new LatLng(14.507577, 121.004456))
                .anchor(0.5f, 0.5f)
                .title("title")
                .snippet("snippet")
                .icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_CYAN)));

Answer 2

You can add a method to MapFragment called setLocation and call it in MainActivity.

Like this:

MapFragment

// Location mCurrentLoc = null;

public void setLocation(Location loc) {
    mCurrentLoc = loc;
    if (mMap != null) {
        //do fragment location stuff
    }
}

@Override
public void onMapReady(GoogleMap googleMap) {
    // all your above code

    if (mCurrentLocation != null) {
        // do fragment location stuff
    }
}

MainActivity

mapFragment.setLocation(mLocal);

Answer 3

为了从活动数据传递到片段，您可以使用Bundle把你的变量，并设置片段的说法与此Bundle或者您可以使用另一种方法（我没有看到你的整个项目得到确保其更好的办法） EventBus

Answer 4

You have the instance of MapFragment as mapFragment right?

So create a public method in MapFragment.class as getCoordinates

    public void getCoordinates(double latitude, double longitude){
         this.latitude = latitude;
         this.longitude = longitude;
}

Send coordinates from Activity to fragment as below

if(mapFragment instanceOf MapFragment){
 ((MapFragment)mapFragment).getCoordinates(latitude, longitude);

Answer 5

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

        initLocationFetching(MainActivity.this);

    mapFragment = new MapFragment(MainActivity.this, this);
    manager = getSupportFragmentManager();
}
 @Override
    public void locationFetched(Location mLocal, Location oldLocation, String time, String locationProvider) {
    super.locationFetched(mLocal, oldLocation, time, locationProvider);
 //After initLocationFetching.
 Bundle bundle = new Bundle();
 bundle.putDouble("Lat",mLocal.getLatitude());
 bundle.putDouble("Long"mLocal.getLongitude());
 mapFragment.setArguments(bundle);
 manager.beginTransaction().replace(R.id.mainLayout, mapFragment).commit();
}



//In MapFragment
class MapFragment extends Fragment implements OnMapReadyCallback,
        GoogleApiClient.OnConnectionFailedListener {
double lati=0.0;
double longi=0.0;

@Override
public void onCreate(Bundle bundle){
lati=getArguments().getDouble("Lat");
longi=getArguments().getDouble("Long");
}

@Override
public void onMapReady(GoogleMap googleMap) {
    mMap = googleMap;

    LatLng origin = new LatLng(lati,longi);

    mMap.addMarker(new MarkerOptions()
            .position(new LatLng(lati,longi))
            .anchor(0.5f, 0.5f)
            .title("title")
            .snippet("snippet")
            .icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_CYAN)));

    mMap.animateCamera(CameraUpdateFactory.newLatLngZoom(new LatLng(value1, value2), 9.0f));

}

Answer 6

You must create an instance of your activity and thus pass the data of it to your fragment

In your fragment, Declare a variable of your MainActivity to obtain the context of it and thus be able to work with it on the fragment and declares the variable to which you want to assign the value that it contains in the MainActivity and pass the value on the onAttach method. onAttch is called when a fragment is first attached to its context.

private MainActivity mActivity;
private String mData;

Now in the onAttach method that is when the fragment adheres to its container which is the main activity.

@Override
public void onAttach(Context context) {
    super.onAttach(context);
    //Verify if mActivity is null and it is MainActivity context
    if (mActivity == null && context instanceof MainActivity) {
        mActivity = (MainActivity) getActivity();
        //Checking for a NPE       
        if(mActivity != null){
         mData = mActivity.MyMainActivityVariable;
       }
     }
   }

And in the onDetach method Called when the fragment is no longer attached to its activity.

@Override
public void onDetach() {
    super.onDetach();
    mActivity = null;
    }

Now we can work with the variable we want to use from the MainActivity. This is using Support Library Fragment For more info about Fragments go to Fragment Android Developers