身份验证时 Firebase .getUID NullPointerException

我注册时会将数据添加到数据库中，但是我得到了

Java.lang.NullPointerException：尝试在空对象引用上调用虚拟方法“java.lang.String com.google.firebase.auth.FirebaseUser.getUid()”

我尝试了一些东西，但没有成功

这是我的代码

    auth = FirebaseAuth.getInstance();

    database = FirebaseDatabase.getInstance();

    mRef = database.getReference();
    FirebaseUser user = auth.getCurrentUser();
    userID = user.getUid();
btnSignUp.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            final String fname = etFname.getText().toString().trim();
            final String lname = etLname.getText().toString().trim();
            final String id_card = etIdCard.getText().toString().trim();
            final String email = etEmail.getText().toString().trim();
            final String mobile = etMobile.getText().toString().trim();
            String password = etPassword.getText().toString().trim();

            if (TextUtils.isEmpty(email)){
                Toast.makeText(getApplicationContext(), "Enter email address!", Toast.LENGTH_SHORT).show();
                return;
            }

            if (TextUtils.isEmpty(password)){
                Toast.makeText(getApplicationContext(), "Enter password!", Toast.LENGTH_SHORT).show();
                return;
            }

            if (TextUtils.isEmpty(fname)){
                Toast.makeText(getApplicationContext(), "Enter FirstName!", Toast.LENGTH_SHORT).show();
                return;
            }

            if (password.length() < 8) {
                Toast.makeText(getApplicationContext(), "Password too short, enter minimum 8 characters!", Toast.LENGTH_SHORT).show();
                return;
            }

            progressBar.setVisibility(View.VISIBLE);

            auth.createUserWithEmailAndPassword(email,password)
                    .addOnCompleteListener(new OnCompleteListener<AuthResult>() {
                        @Override
                        public void onComplete(@NonNull Task<AuthResult> task) {


                            if (!task.isSuccessful()) {

                                UserInfo userInfo = new UserInfo(fname,lname,id_card,mobile,email);
                                mRef.child("users").child(userID).setValue(userInfo);
                                etFname.setText("");
                                etLname.setText("");
                                etIdCard.setText("");
                                etMobile.setText("");
                                etEmail.setText("");
                                Toast.makeText(RegisterActivity.this, "Authentication failed." + task.getException(),
                                        Toast.LENGTH_SHORT).show();

                            } else {
                                Toast.makeText(RegisterActivity.this, "Register Successfully" + task.isSuccessful(), Toast.LENGTH_SHORT).show();
                                progressBar.setVisibility(View.GONE);

                                finish();
                            }

                        }
                    });
        }
    });


}

现在得到这样的新错误 java.lang.NoSuchMethodError：类 Lcom/google/firebase/FirebaseApp 中没有虚拟方法 zzTt()Z；或其超类（“com.google.firebase.FirebaseApp”的声明出现在 /data/app/com.example.androiddev.army31-1/split_lib_dependency_apk.apk:classes36.dex 中）

现在我可以修复它，因为在 gradle 上编译不是同一版本

并得到了同样的东西

您在代码中提到的身份验证类型是什么，将其替换为单行并检查它是否有效

        String mUid = FirebaseAuth.getInstance().getCurrentUser().getUid();

您还可以查看文档以获取完整的工作代码示例：https://firebase.google.com/docs/auth/android/manage-users https://firebase.google.com/docs/auth/android/manage-users