、どうすれば修正できますか？ E/UncaughtException：java.lang.NullPointerException：仮想メソッドを呼び出そうとしました

Question

こんにちは私は次のエラーがあります どのファイルが競合している可能性がありますか？

私はこれはエラー

1. このエラー

 


> it.unipi.iet.namefirebase E/UncaughtException: 
> java.lang.NullPointerException: Attempt to invoke virtual method 
> 'java.lang.String 
> com.google.firebase.auth.FirebaseUser.getProviderId()' on a null 
> object reference 
>            at it.unipi.iet.namefirebase.MainActivity$4$1.onComplete(MainActivity.java:112) 
>            at com.google.android.gms.tasks.zzc$1.run(Unknown Source) 
>            at android.os.Handler.handleCallback(Handler.java:739) 
>            at android.os.Handler.dispatchMessage(Handler.java:95) 
>            at android.os.Looper.loop(Looper.java:148) 
>            at android.app.ActivityThread.main(ActivityThread.java:5417) 
>            at java.lang.reflect.Method.invoke(Native Method) 
>            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
>            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
> it.unipi.iet.namefirebase D/FA: Logging event (FE): _ae, 
> Bundle[{_o=crash, timestamp=1509341623773, fatal=1}] 
> it.unipi.iet.namefirebase V/FA: Using measurement service 
> it.unipi.iet.namefirebase V/FA: Connecting to remote service 
> com.google.android.gms W/FirebaseAuth: [PhoneNumberAuthPostProcessor] 
> postProcess starts com.google.android.gms W/FirebaseAuth: 
> [PhoneNumberAuthPostProcessor] postProcess ends 
> it.unipi.iet.namefirebase E/AndroidRuntime: FATAL EXCEPTION: main 
>          Process: it.unipi.iet.namefirebase, PID: 6000 
>          java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String 
> com.google.firebase.auth.FirebaseUser.getProviderId()' on a null 
> object reference 
>           at it.unipi.iet.namefirebase.MainActivity$4$1.onComplete(MainActivity.java:112) 
>           at com.google.android.gms.tasks.zzc$1.run(Unknown Source) 
>           at android.os.Handler.handleCallback(Handler.java:739) 
>           at android.os.Handler.dispatchMessage(Handler.java:95) 
>           at android.os.Looper.loop(Looper.java:148) 
>           at android.app.ActivityThread.main(ActivityThread.java:5417) 
>           at java.lang.reflect.Method.invoke(Native Method) 
>           at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
>           at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
> system_process W/ActivityManager: Force finishing activity 
> it.unipi.iet.namefirebase/.MainActivity ? D/gralloc_ranchu: 
> gralloc_alloc: Creating ashmem region of size 1806336 
> it.unipi.iet.namefirebase I/FirebaseCrash: Sending crashes ? 
> E/EGL_emulation: tid 1208: eglCreateSyncKHR(1881): error 0x3004 
> (EGL_BAD_ATTRIBUTE) 

コードmainactivity

package it.unipi.iet.namefirebase; 

import android.app.Activity; 
import android.content.Intent; 
import android.os.Bundle; 
import android.support.annotation.NonNull; 
import android.util.Log; 
import android.view.View; 
import android.widget.Button; 
import android.widget.Toast; 
import iit.unipi.iet.namefirebase.utilities.AuthUtilities; 
import it.unipi.iet.namefirebase.utilities.DatabaseUtilities; 
import com.facebook.AccessToken; 
import com.facebook.CallbackManager; 
import com.facebook.FacebookCallback; 
import com.facebook.FacebookException; 
import com.facebook.FacebookSdk; 
import com.facebook.login.LoginResult; 
import com.facebook.login.widget.LoginButton; 
import com.google.android.gms.tasks.OnCompleteListener; 
import com.google.android.gms.tasks.Task; 
import com.google.firebase.auth.AuthCredential; 
import com.google.firebase.auth.AuthResult; 
import com.google.firebase.auth.FacebookAuthProvider; 
import com.google.firebase.auth.FirebaseUser; 



public class MainActivity extends Activity{ 

    public static final String SIGN = "it.unipi.iet.namefirebase.SIGN"; 
    private final String TAG = "MainActivity"; 
    private AuthUtilities AuthUt; 
    private CallbackManager callbackManager; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     FacebookSdk.sdkInitialize(getApplicationContext()); 
     callbackManager = CallbackManager.Factory.create(); 
     setContentView(R.layout.activity_main); 


     // Check Authentication 
     AuthUt = new AuthUtilities(); 
     if(AuthUt.getUser() != null){ 
      // if user is already logged changes activity 
      Log.d(TAG,"User already logged"); 
      Intent i = new Intent(MainActivity.this,MapsActivity.class); 
      startActivity(i);} 
     else{ 
      Log.d(TAG,"User not logged yet"); 
      } 

     // Sign in Button 
     final Button SignIn = (Button) findViewById(R.id.button); 
     SignIn.setOnClickListener(new View.OnClickListener(){ 
      public void onClick(View v){ 
       Intent intent = new Intent(MainActivity.this,LoginActivity.class); 
       intent.putExtra(SIGN,"sign-in"); 
       startActivity(intent); 
      } 
     }); 

     // Sign up with email Button 
     final Button SignUp = (Button) findViewById(R.id.button2); 
     SignUp.setOnClickListener(new View.OnClickListener(){ 
      public void onClick(View v){ 
       Intent intent = new Intent(MainActivity.this,LoginActivity.class); 
       intent.putExtra(SIGN,"sign-up"); 
       startActivity(intent); 
      } 
     }); 

     // Connect with Facebook button 
     FacebookSdk.sdkInitialize(getApplicationContext()); 
     callbackManager = CallbackManager.Factory.create(); 
     LoginButton loginButton = (LoginButton) findViewById(R.id.button3); 
     loginButton.setReadPermissions("email", "public_profile"); 
     loginButton.registerCallback(callbackManager, new FacebookCallback<LoginResult>() { 
      @Override 
      public void onSuccess(LoginResult loginResult) { 
       Log.d(TAG, "facebook:onSuccess:" + loginResult); 
       handleFacebookAccessToken(loginResult.getAccessToken()); 

      } 

      @Override 
      public void onCancel() { 
       Log.d(TAG, "facebook:onCancel"); 
       // ... 
      } 

      @Override 
      public void onError(FacebookException error) { 
       Log.d(TAG, "facebook:onError", error); 
       // ... 
      } 
     }); 

     // Browse as a guest button 
     final Button GuestUser = (Button) findViewById(R.id.button4); 
     GuestUser.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       // signin_anonymously 
       AuthUt.get_mAuth().signInAnonymously() 
         .addOnCompleteListener(MainActivity.this, new OnCompleteListener<AuthResult>() { 
          @Override 
          public void onComplete(@NonNull Task<AuthResult> task) { 
           Log.d(TAG, "signInAnonymously:onComplete:" + task.isSuccessful()); 
           Log.d(TAG,"User Provider: "+ AuthUt.get_mAuth().getCurrentUser().getProviderId()); 
           // start MapsActivity 
           Intent i = new Intent(MainActivity.this,MapsActivity.class); 
           startActivity(i); 

           // If sign in fails, display a message to the user. If sign in succeeds 
           // the auth state listener will be notified and logic to handle the 
           // signed in user can be handled in the listener. 
           if (!task.isSuccessful()) { 
            Log.w(TAG, "signInAnonymously", task.getException()); 
            Toast.makeText(MainActivity.this, "Authentication failed.", 
              Toast.LENGTH_SHORT).show(); 
           } 


          } 
         }); 
      } 
     }); 



    } 

    @Override 
    public void onStart() { 
     super.onStart(); 
     AuthUt.addListner(); 
    } 

    @Override 
    public void onStop() { 
     super.onStop(); 
     AuthUt.removeListener(); 
    } 

    /* 
    * Disable going back function 
    */ 
    @Override 
    public void onBackPressed() { 
     // disable going back to the previous Activity 
     moveTaskToBack(true); 
    } 

    @Override 
    protected void onActivityResult(int requestCode, int resultCode, Intent data) { 
     super.onActivityResult(requestCode, resultCode, data); 
     callbackManager.onActivityResult(requestCode, resultCode, data); 
    } 

    private void handleFacebookAccessToken(AccessToken token) { 
     Log.d(TAG, "handleFacebookAccessToken:" + token); 

     AuthCredential credential = FacebookAuthProvider.getCredential(token.getToken()); 

     AuthUt.get_mAuth().signInWithCredential(credential) 
       .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() { 
        @Override 
        public void onComplete(@NonNull Task<AuthResult> task) { 
         Log.d(TAG, "signInWithCredential:onComplete:" + task.isSuccessful()); 
         FirebaseUser user = AuthUt.get_mAuth().getCurrentUser(); 
         Log.d(TAG,"url "+user.getPhotoUrl()); 
         DatabaseUtilities db = new DatabaseUtilities(); 
         db.writeNewUser(user.getUid(),user.getDisplayName(),null,user.getPhotoUrl().toString(),null, null); 
         Log.d(TAG,"Fb user created"); 
         // start MapsActivity 
         Intent i = new Intent(MainActivity.this,MapsActivity.class); 
         startActivity(i); 
         // If sign in fails, display a message to the user. If sign in succeeds 
         // the auth state listener will be notified and logic to handle the 
         // signed in user can be handled in the listener. 
         if (!task.isSuccessful()) { 
          Log.w(TAG, "signInWithCredential", task.getException()); 
          Toast.makeText(MainActivity.this, "Authentication failed.", 
            Toast.LENGTH_SHORT).show(); 
         } 

        } 
       }); 
    } 




} 

ですgithubの にプロジェクトを見つけました

Answer 1

オブジェクトを使用する前にヌルチェックを行う必要があります。

if(yourObject != null) 
    { 
     int id = yourObject.getProviderId(); 
    } else{ 
     // Handle what if null 
    } 

また、オブジェクトが時々nullになるかどうかわからない場合は、try {} catch {}ブロックを使用してください。