我试图开发登录facebook sdk，但我有错误：
java.lang.ClassCastException: com.app.loginsample.MainActivity cannot be cast to android.app.Activity
在MainActivity类中，我写了这个：
public class MainActivity extends Fragment {
private TextView textDetails;
private CallbackManager callbackManager;
private AccessTokenTracker mTokenTracker;
private ProfileTracker mProfileTracker;
private FacebookCallback<LoginResult> callback = new FacebookCallback<LoginResult>() {
@Override
public void onSuccess(LoginResult loginResult) {
AccessToken accessToken = loginResult.getAccessToken();
Profile profile = Profile.getCurrentProfile();
displayWelcomeMessage(profile);
}
@Override
public void onCancel() {
}
@Override
public void onError(FacebookException error) {
}
};
public MainActivity(){
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
FacebookSdk.sdkInitialize(getActivity().getApplicationContext());
callbackManager = CallbackManager.Factory.create();
mTokenTracker = new AccessTokenTracker() {
@Override
protected void onCurrentAccessTokenChanged(AccessToken oldToken, AccessToken newToken) {
}
};
mProfileTracker = new ProfileTracker() {
@Override
protected void onCurrentProfileChanged(Profile oldProfile, Profile newProfile) {
}
};
mTokenTracker.startTracking();
mProfileTracker.startTracking();
}
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.activity_main, container, false);
}
private void displayWelcomeMessage(Profile profile){
if(profile!=null){
textDetails.setText("Welcome " + profile.getName());
}
}
@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
LoginButton loginButton = (LoginButton) view.findViewById(R.id.login_button);
loginButton.setReadPermissions("user_friends");
// If using in a fragment
loginButton.setFragment(this);
// Other app specific specialization
loginButton.registerCallback(callbackManager, callback);
textDetails = (TextView)view.findViewById(R.id.textView);
}
@Override
public void onResume() {
super.onResume();
Profile profile = Profile.getCurrentProfile();
displayWelcomeMessage(profile);
}
@Override
public void onStop() {
super.onStop();
mTokenTracker.stopTracking();
mProfileTracker.stopTracking();
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
callbackManager.onActivityResult(requestCode, resultCode, data);
}
}