'Person()' 在 'android.app.Person' 中具有私有访问权限

Question

I am trying to insert a new country into the database without using the push() function, but the data override them in the database. So I found to use Person class.

public class AddCountriesActivity extends AppCompatActivity {
    EditText country;
    Button insert;

 @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_add_countries);
        insert = findViewById(R.id.insert);
        country = findViewById(R.id.country);
       
 insert.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                uploadToFirebase();
            }
        });
}

 protected void uploadToFirebase(){
        String countrydb = country.getText().toString().trim();

        FirebaseDatabase db = FirebaseDatabase.getInstance();
        DatabaseReference root = db.getReference("Countries");
        Person person = new Person();
        person.setName(countrydb);
        String s = "country";
        root.child(s).setValue(person);
}
}

But the error occur that is given below:

'Person()' has private access in 'android.app.Person' Cannot resolve method 'setName' in 'Person'

Please guide me that where I am making a mistake. Thank you!

Answer 1

You're getting the following error:

'Person()' has private access in 'android.app.Person'

Because there is no way you can create a new instance of the Person class. Why? because the constructor of the class is private:

private Person() {
    throw new RuntimeException("Stub!");
}

So in order to write an object in the Realtime Database, the class should contain a public no-argument constructor. That being said, to solve this issue, you have to create your own Person class. At a minimum, it should look like this:

class Person {
    String name;
}

In which the constructor is provided by the JVM, or if you want to use encapsulation:

class Person {
    private String name;

    public Person() {} //👈

    Person(String name) {
        this.name = name;
    }

    setName(String name) {
        this.name = name;
    }
}