Question

我正在尝试从Firebase Realtime获取FirebaseLocationData对象 Android中的数据库。

根据Docs，该类应该没有我所做的参数构造函数 public FirebaseLocationData() {}但它仍然显示错误

com.google.firebase.database.DatabaseException: Class android.location.Location does not define a no-argument constructor. If you are using ProGuard, make sure these constructors are not stripped.

我应该如何制作 android.location.Location 类的无参数构造函数？

此行FirebaseLocationData fld = dataSnapshot.getValue(FirebaseLocationData.class);

产生错误

码

 public void onChildAdded(DataSnapshot dataSnapshot, String previousChildName) {
            Log.d(TAG, "onChildAdded:" + dataSnapshot.getKey());

            FirebaseLocationData fld = dataSnapshot.getValue(FirebaseLocationData.class);
            Toast.makeText(MainActivity.this, fld.getEmail()+" added", Toast.LENGTH_SHORT).show();

        }

FirebaseLocationData类：

public class FirebaseLocationData {
String email;
Location location;
String time;

public FirebaseLocationData() {
}

public FirebaseLocationData(Location location, String email, String time) {
    this.location = location;
    this.email = email;
    this.time = time;
}

public String getEmail() {
    return email;
}

public void setEmail(String email) {
    this.email = email;
}

public String getTime() {
    return time;
}

public void setTime(String time) {
    this.time = time;
}

public Location getLocation() {
    return location;
}

public void setLocation(Location location) {
    this.location = location;
}

}

Answer 1

您正在尝试编写Elements contentinstantiate = doc.select("span.mw-headline, h3 ~ a"); for (int i=0; i < contentinstantiate.size(); i++) { System.out.println(contentinstantiate.get(i).text()); }对象，并且类没有公共的无参数构造函数。许多Android库类都不符合Firebase的要求，您必须编写自己的序列化/反序列化来与数据库交换必要的信息。

另见：Class android.location.Location does not define a no-argument constructor

如何为Firebase数据库异常添加内置类的无参数构造函数？

1 个答案: