java.lang.NullPointerException：尝试调用虚方法’java.lang.String com.google.firebase.auth.FirebaseUser.getUid（）’

Process: com.example.vicevirus.myapplication, PID: 13471 java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String com.google.firebase.auth.FirebaseUser.getUid()' on a null object reference at com.example.vicevirus.myapplication.RegisterActivity$1.onComplete(RegisterActivity.java:48) at com.google.android.gms.tasks.zzc$1.run(Unknown Source) at android.os.Handler.handleCallback(Handler.java:751) at android.os.Handler.dispatchMessage(Handler.java:95) at android.os.Looper.loop(Looper.java:154) at android.app.ActivityThread.main(ActivityThread.java:6119) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776) 

这是在Android监视器上。 我该如何解决这个问题？

 package com.example.vicevirus.myapplication; import android.app.ProgressDialog; import android.support.annotation.NonNull; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.View; import android.widget.EditText; import android.widget.Toast; import com.google.android.gms.tasks.OnCompleteListener; import com.google.android.gms.tasks.OnSuccessListener; import com.google.android.gms.tasks.Task; import com.google.firebase.auth.AuthResult; import com.google.firebase.auth.FirebaseAuth; import com.google.firebase.database.DatabaseReference; import com.google.firebase.database.FirebaseDatabase; public class RegisterActivity extends AppCompatActivity { private EditText email,name,password; DatabaseReference databaseReference; FirebaseAuth mAuth; private DatabaseReference userIdRef; ProgressDialog registerDialog; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_register); email=(EditText)findViewById(R.id.email); name=(EditText)findViewById(R.id.name); password=(EditText)findViewById(R.id.password); databaseReference= FirebaseDatabase.getInstance().getReference().child("chat_users"); mAuth=FirebaseAuth.getInstance(); registerDialog=new ProgressDialog(this); registerDialog.setMessage("Registering.."); } public void submit(View view) { registerDialog.show(); mAuth.createUserWithEmailAndPassword(email.getText().toString(),password.getText().toString()).addOnCompleteListener(this, new OnCompleteListener() { @Override public void onComplete(@NonNull Task task) { if(task.isComplete()) { registerDialog.dismiss(); Toast.makeText(getApplicationContext(),"Registered successfully",Toast.LENGTH_SHORT).show(); userIdRef=databaseReference.child(mAuth.getCurrentUser().getUid()); userIdRef.child("name").setValue(name.getText().toString()); finish(); } registerDialog.dismiss(); } }); } } 

Answer 1

问题似乎是您的用户尚未登录或甚至已注册。 所以调用mAuth.getCurrentUser()返回null。

查看FireBase文档的此页面，了解如何实现用户注册。 可能是失败了。 检查task.isSuccessful()是必要的。