空对象错误Firebase数据库上的ANDROID_ID调用

Question

我是Android应用程序开发的新手。我一直试图用Firebase电子邮件和密码auth构建一个应用程序，并试图在注册过程中将手机的android_id保存在Firebase数据库中。

public class SignUpActivity extends AppCompatActivity implements View.OnClickListener {

    private EditText editTextName;
    private FirebaseAuth mAuth;
    public String androidId = Settings.Secure.getString(getContentResolver(), Settings.Secure.ANDROID_ID);

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_signup);
        editTextName = findViewById(R.id.edit_text_name);
        mAuth = FirebaseAuth.getInstance();
    }

    private void registerUser() {
        final String name = editTextName.getText().toString().trim();
        mAuth.createUserWithEmailAndPassword(email, password)
            .addOnCompleteListener(new OnCompleteListener < AuthResult > () {
                @Override
                public void onComplete(@NonNull Task < AuthResult > task) {
                    if (task.isSuccessful()) {

                        User user = new User(
                            name,
                            androidId
                        );

                        FirebaseDatabase.getInstance().getReference("Users")
                            .child(FirebaseAuth.getInstance().getCurrentUser().getUid())
                            .setValue(user).addOnCompleteListener(new OnCompleteListener < Void > () {
                                @Override
                                public void onComplete(@NonNull Task < Void > task) {
                                    //
                                }
                            });

                    } else {
                        //
                    }
                }
            });
    }
}

public class User {
    public String name;


    public User() {

    }

    public User(String name) {
        this.name = name;
    }
}

Answer 1

在oncreate()方法中获取androidid

试试这个

public class SignUpActivity extends AppCompatActivity implements View.OnClickListener {

    private EditText editTextName;
    private FirebaseAuth mAuth;
    public String androidId;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_signup);
        editTextName = findViewById(R.id.edit_text_name);
        mAuth = FirebaseAuth.getInstance();
        androidId = Settings.Secure.getString(getContentResolver(), Settings.Secure.ANDROID_ID);
    }

    private void registerUser() {
        final String name = editTextName.getText().toString().trim();
        mAuth.createUserWithEmailAndPassword(email, password)
            .addOnCompleteListener(new OnCompleteListener < AuthResult > () {
                @Override
                public void onComplete(@NonNull Task < AuthResult > task) {
                    if (task.isSuccessful()) {

                        User user = new User(
                            name,
                            androidId
                        );

                        FirebaseDatabase.getInstance().getReference("Users")
                            .child(FirebaseAuth.getInstance().getCurrentUser().getUid())
                            .setValue(user).addOnCompleteListener(new OnCompleteListener < Void > () {
                                @Override
                                public void onComplete(@NonNull Task < Void > task) {
                                    //
                                }
                            });

                    } else {
                        //
                    }
                }
            });
    }
}