从firebase中的子节点检索数据，并使用构造函数类显示为textview

ukxgm1gy  于 2021-09-13  发布在  Java
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更新：我已设法从我的数据库中检索特定的狗数据（请参阅 .child("moo") 在下面我将push（）元素从 SignUp 类，以便将狗的名称用作id，而不是唯一的id。但是，如果用户有多只狗，那么最好的方法是什么？我如何遍历特定的狗？我如何才能显示特定的狗信息？
我正在尝试从firebase数据库中检索数据，并在 TextView ，我已经在项目的其他地方完成了这项工作，没有任何问题，但由于某些原因，无法从构造函数类检索get/set方法。我正在寻找一些帮助，找出原因，因为我已经做了几个小时了，但找不到解决方案。。
基本上，我想从每个独特的狗的用户下检索数据，并在相应的 TextView 我的dogprofile类中的元素。这段代码不起作用，它抛出了一个nullobjectref错误，但我真的不知道如何修复它，我想我需要弄清楚如何访问当前的dog元素？如果用户有不止一只狗，那么这可能是一个问题。。
我的firebase Hiarachy：

狗狗建造师：

public class Dog {
    private String name, breed, age, weight, gender, neutered;

    public Dog() {

    }

    public Dog (String name, String breed, String age, String weight, String gender, String neutered) {
        this.name = name;
        this.breed = breed;
        this.age = age;
        this.weight = weight;
        this.gender = gender;
        this.neutered = neutered;
    }

    public String getName() {
        return name;
    }

    public String getBreed() {
        return breed;
    }

    public String getAge() {
        return age;
    }

    public String getWeight() { return weight; }

    public String getGender() { return gender; }

    public String getNeutered() { return neutered; }
}

狗资料类别：

public class DogProfile extends AppCompatActivity {

    private FirebaseAuth firebaseAuth;
    private FirebaseUser currentUser;

    TextView breed, age, dogGender, weight, isNeutered;
    String uid;
    String dogId;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.dog_profile);

        firebaseAuth = FirebaseAuth.getInstance();
        currentUser = firebaseAuth.getCurrentUser();
        uid = currentUser.getUid();

        breed = findViewById(R.id.breed);
        age = findViewById(R.id.age);
        dogGender = findViewById(R.id.gender);
        weight = findViewById(R.id.weight);
        isNeutered = findViewById(R.id.neutered);

        DatabaseReference databaseReference = FirebaseDatabase.getInstance("").getReference("user").child(uid).child("dogs");

        databaseReference.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {

 for (DataSnapshot ds : dataSnapshot.getChildren()) {
                String dogBreed = ds.child("breed").getValue(String.class);
                String dogAge = ds.child("age").getValue(String.class);
                String gender = ds.child("gender").getValue(String.class);
                String dogWeight = ds.child("weight").getValue(String.class);
                String neutered = ds.child("neutered").getValue(String.class);

                breed.setText(dogBreed);
                age.setText(dogAge);
                dogGender.setText(gender);
                weight.setText(dogWeight);
                isNeutered.setText(neutered);
            }

            }

            @Override
            public void onCancelled(DatabaseError databaseError) {
                Log.w("TAG", "onCancelled", databaseError.toException());
            }
        });

        }
    }

xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:tools="http://schemas.android.com/tools"
    tools:context=".DogProfile">

    <androidx.constraintlayout.widget.ConstraintLayout
        android:id="@+id/constraintLayout2"
        android:layout_width="match_parent"
        android:layout_height="264dp"
        android:background="@color/olive"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">

        <ImageView
            android:id="@+id/imageView2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            tools:srcCompat="@tools:sample/avatars" />

    </androidx.constraintlayout.widget.ConstraintLayout>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="393dp"
        android:layout_height="560dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/constraintLayout2">

        <Spinner
            android:id="@+id/age"
            android:layout_width="160dp"
            android:layout_height="59dp"
            android:autofillHints="age"
            android:background="@drawable/spinner_bg"
            android:hint="Age"
            android:inputType="text"
            android:labelFor="@+id/name"
            android:spinnerMode="dropdown"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.085"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintVertical_bias="0.353" />

        <Spinner
            android:id="@+id/weight"
            android:layout_width="160dp"
            android:layout_height="61dp"
            android:autofillHints="weight"
            android:background="@drawable/spinner_bg"
            android:hint="Weight (kg)"
            android:inputType="text"
            android:labelFor="@+id/name"
            android:spinnerMode="dropdown"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.901"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintVertical_bias="0.356" />

        <TextView
            android:id="@+id/breed"
            android:layout_width="347dp"
            android:layout_height="57dp"
            android:autofillHints="breed"
            android:background="@drawable/spinner_bg"
            android:focusable="true"
            android:hint="Breed"
            android:inputType="text"
            android:labelFor="@+id/name"
            android:spinnerMode="dropdown"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.434"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintVertical_bias="0.196" />

        <EditText
            android:id="@+id/name"
            android:layout_width="354dp"
            android:layout_height="56dp"
            android:autofillHints="Name"
            android:background="@drawable/text_field"
            android:hint="Name"
            android:inputType="text"
            android:labelFor="@+id/name"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.495"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintVertical_bias="0.032"></EditText>

        <Spinner
            android:id="@+id/gender"
            android:layout_width="160dp"
            android:layout_height="61dp"
            android:autofillHints="gender"
            android:background="@drawable/spinner_bg"
            android:hint="Gender"
            android:inputType="text"
            android:labelFor="@+id/name"
            android:spinnerMode="dropdown"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.086"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintVertical_bias="0.532" />

        <Spinner
            android:id="@+id/neutered"
            android:layout_width="160dp"
            android:layout_height="56dp"
            android:autofillHints="neutered"
            android:background="@drawable/spinner_bg"
            android:hint="Neutered?"
            android:inputType="text"
            android:labelFor="@+id/name"
            android:spinnerMode="dropdown"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.901"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintVertical_bias="0.535" />

        <TextView
            android:id="@+id/textView"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Daily Exercise Goal"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.058"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintVertical_bias="0.665" />

        <View
            android:id="@+id/divider"
            android:layout_width="match_parent"
            android:layout_height="1dp"
            android:background="?android:attr/listDivider"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.0"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintVertical_bias="0.624" />

    </androidx.constraintlayout.widget.ConstraintLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
Javaandroidfirebase-realtime-databasefirebase

1条答案

按热度按时间
ndasle7k

ndasle7k1#

因为它在列表中，所以我认为您想要检索狗的列表。你需要使用 for loop .

breedRef.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            String dogBreed;
            List<Dog> dogList;
             for (DataSnapshot snapshot : dataSnapshot.getChildren()) {
                final Dog dog = snapshot.getValue(Dog.class);
                dogList.add(dog);
                dogBreed += dog.getBreed();

            }
            breed.setText(currentUser.getBreed());
            // -------------

            Log.i("TAG", dataSnapshot.getValue(String.class));
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {
            Log.w("TAG", "onCancelled", databaseError.toException());
        }
    });
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