在我的应用程序中，我的main_activity包含if($imgSize < 5000000)和FrameLayout
Fragment我需要拨打public class Fragment1 extends Fragment {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment1, container, false);
return view;
}
public class StartAsyncTask extends AsyncTask<Void,Void,Void>{
@Override
protected Void doInBackground(Void... voids) {
Log.e("startAsyncTask", "start");
return null;
}
}
}
中的AsyncTask，
所以我用：
MainActivity但它不起作用。 @Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
android.support.v4.app.FragmentTransaction fragmentTransaction =
getSupportFragmentManager().beginTransaction();
Fragment1 fragment1 = new Fragment1();
fragmentTransaction.replace(R.id.fragment, fragment1).commit();
new Fragment1.StartAsyncTask().execute();
}
为红色，（不包含类）错误。
答案 0 :(得分：2)
你可以这样做，从你的MainActivity你可以间接调用你的AsyncTask
ublic class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
android.support.v4.app.FragmentTransaction fragmentTransaction =
getSupportFragmentManager().beginTransaction();
BlankFragment fragment1 = new BlankFragment();
fragmentTransaction.replace(R.id.activity_main, fragment1).commit();
fragment1.startASycnc();
}
}
你的片段看起来像这样：
public class BlankFragment extends Fragment {
public BlankFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_blank, container, false);
}
public void startASycnc() {
new StartAsyncTask().execute();
}
public class StartAsyncTask extends AsyncTask<Void, Void, Void> {
@Override
protected Void doInBackground(Void... voids) {
Log.e("startAsyncTask", "start");
return null;
}
}
}
答案 1 :(得分：0)
StartAsyncTask是Fragment的内部类，而不是方法。如果你真的需要在Fragment中触发某些事情，那么让它公开一个公共方法，该方法采取适当的行动，而不是让一个类在它之外的方法知道它的内部。
答案 2 :(得分：0)
这就是我的做法
public class MyFriendsLocationUpdate extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... params) {
while (true) {
System.out.println("working 1");
if (getActivity() != null) {
System.out.println("working 2");
if (FirebaseAuth.getInstance().getCurrentUser() != null) {
System.out.println("working 3");
DatabaseReference reference = FirebaseDatabase.getInstance().getReference(Comman.FRIENDS_REF).child(FirebaseAuth.getInstance().getCurrentUser().getUid());
reference.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
for (DataSnapshot snapshot : dataSnapshot.getChildren()) {
final FriendsModel friendsModel = snapshot.getValue(FriendsModel.class);
DatabaseReference reference1 = FirebaseDatabase.getInstance().getReference(Comman.PUBLIC_LOCATION_REF).child(friendsModel.getFrienduid()).child("l");
reference1.addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(@NonNull final DataSnapshot dataSnap) {
if (dataSnap.hasChild("0")) {
Picasso.get().load(friendsModel.getFriendimgurl())
.into(new Target() {
@Override
public void onBitmapLoaded(Bitmap bitmap, Picasso.LoadedFrom from) {
if (markerFriend != null) {
markerFriend.remove();
}
double lat = (double) dataSnap.child("0").getValue();
double lng = (double) dataSnap.child("1").getValue();
System.out.println("lat = " + lat);
System.out.println("Your Friend " + friendsModel.getFriendname() + " is Here");
MarkerOptions markerOptions = new MarkerOptions();
markerOptions.position(new LatLng(lat, lng));
markerOptions.icon(BitmapDescriptorFactory.fromBitmap(getMarkerBitmapFromView(bitmap)));
markerOptions.title("Your Friend " + friendsModel.getFriendname() + "");
// markerOptions.icon(BitmapDescriptorFactory.fromResource(R.drawable.ic_person_marker));
markerFriend = mMap.addMarker(markerOptions);
if (isSharingValue.equals("true")) {
setupMapIfNeeded();
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (checkLocationPermission() && checkLocation())//check whether location service is enable or not in your phone
{
setupLocation();
}
} else {
if (checkLocation())//check whether location service is enable or not in your phone
{
setupLocation();
}
}
}
}
@Override
public void onBitmapFailed(Exception e, Drawable errorDrawable) {
double lat = (double) dataSnap.child("latitude").getValue();
double lng = (double) dataSnap.child("longitude").getValue();
System.out.println("lat = " + lat);
System.out.println("You Friend " + friendsModel.getFriendname() + " is Here");
MarkerOptions markerOptions = new MarkerOptions();
markerOptions.position(new LatLng(lat, lng));
markerOptions.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_GREEN));
markerOptions.title("You Friend " + friendsModel.getFriendname() + "");
// markerOptions.icon(BitmapDescriptorFactory.fromResource(R.drawable.ic_person_marker));
mMap.addMarker(markerOptions);
}
@Override
public void onPrepareLoad(Drawable placeHolderDrawable) {
}
});
for (int i = 0; i < placesArrayList.size(); i++) {
LatLng latLngplace = new LatLng(Double.parseDouble(placesArrayList.get(i).getPlacelat()), Double.parseDouble(placesArrayList.get(i).getPlacelng()));
queryForFriendInThePlace(latLngplace, (Double.parseDouble(placesArrayList.get(i).getPlaceradius()) / 1000), friendsModel.getFrienduid(), friendsModel.getFriendname(), placesArrayList.get(i).getPlacename());
}
} else {
System.out.println("result is: nofriend online");
}
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
}
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
try {
Thread.sleep(4000);
} catch (Exception e) {
e.printStackTrace();
}
// return "Executed";
}
}
}
}
@Override
protected void onPostExecute(String result) {
}
@Override
protected void onPreExecute() {
}
@Override
protected void onProgressUpdate(Void... values) {
}
}
您只需编写即可执行
new MyFriendsLocationUpdate().execute("");