你好，我有以下错误 什么文件可以造成冲突？
我在github上找到了这个项目 这是错误
此错误
> 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)
代码主要活动
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();
}
}
});
}
}
答案 0 :(得分：0)
在使用该对象之前，您必须进行空检查。
if(yourObject != null)
{
int id = yourObject.getProviderId();
} else{
// Handle what if null
}
此外，如果您不确定该对象有时会为空，请务必确保使用try {} catch {}阻止。