Java Firebase实时数据库不显示添加到其中的值。仅显示null

我已经添加了所有依赖项和所有，但是数据仍然没有显示在firebase realtime上 数据库屏幕。Ot仅显示空值。所以我添加了使用firebase的代码

注册屏幕代码：

public class SignUp extends AppCompatActivity {


    TextInputLayout regName, regUsername, regPassword, regEmail, regPhoneno;
    Button regBtn, regLoginbtn;
    FirebaseDatabase rootNode;
    DatabaseReference reference;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_sign_up);

        regName = findViewById(R.id.name);
        regUsername = findViewById(R.id.username);
        regPassword = findViewById(R.id.password);
        regEmail = findViewById(R.id.email);
        regPhoneno = findViewById(R.id.PhoneNo);
        regBtn = findViewById(R.id.button);
        regLoginbtn = findViewById(R.id.button2);

        regBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {


                String name = Objects.requireNonNull(regName.getEditText()).getText().toString();
                String username = Objects.requireNonNull(regUsername.getEditText()).getText().toString();
                String password = Objects.requireNonNull(regPassword.getEditText()).getText().toString();
                String email = Objects.requireNonNull(regEmail.getEditText()).getText().toString();
                String phoneNo = Objects.requireNonNull(regPhoneno.getEditText()).getText().toString();

                UserHelperClass helperClass = new UserHelperClass(name, password, username,  email, phoneNo);
                FirebaseDatabase.getInstance().getReference().child("my").child("users").setValue(helperClass);
            }
        });
    }
}

从应用程序获取数据的类

build.gradle项目：

// Top-level build file where you can add configuration options common to all sub-projects/modules.
buildscript {
    repositories {
        google()
        mavenCentral()
    }
    dependencies {
        classpath "com.android.tools.build:gradle:4.2.1"
        classpath "com.google.gms:google-services:4.3.8"

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        google()
        mavenCentral()
         // Warning: this repository is going to shut down soon
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

build.gradle应用程序：

plugins {
    id 'com.android.application'

}
[enter image description here][1]
android {
    compileSdkVersion 30
    buildToolsVersion "30.0.3"

    defaultConfig {
        applicationId "com.example.medilyf"
        minSdkVersion 16
        targetSdkVersion 30
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
}
apply plugin: 'com.android.application'
apply plugin: 'com.google.gms.google-services'
dependencies {

    implementation platform('com.google.firebase:firebase-bom:28.0.1')
    implementation 'com.google.firebase:firebase-analytics'
    implementation 'androidx.appcompat:appcompat:1.3.0'
    implementation 'com.google.android.material:material:1.3.0'
    implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
    implementation 'com.google.firebase:firebase-database:20.0.0'
    implementation 'org.jetbrains:annotations:15.0'
    testImplementation 'junit:junit:4.13.2'
    androidTestImplementation 'androidx.test.ext:junit:1.1.2'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0'
    implementation 'com.airbnb.android:lottie:3.4.1'
    implementation 'androidx.viewpager2:viewpager2:1.0.0'
}

---

我认为这是因为UserHelperClass对象为空。不要使用重载构造函数来设置值，而是使用模型类的setter。

在setValue之后添加一个

OnCompletelistener

，然后查看错误

---

仅供参考：

如果您检查logcat输出以了解

setValue

何时运行，是否有任何错误消息？您是否尝试将侦听器附加到

.setValue（helperClass）

操作？你有什么错误吗？如何在我的代码中使用它，但在.setValue（“你的值”）中再添加一个参数，

.setValue（“你的值（helperClass）”，新的OnCompleteListener（）{//ovveride functions here}）

下面是一个简单的例子

plugins {
    id 'com.android.application'

}
[enter image description here][1]
android {
    compileSdkVersion 30
    buildToolsVersion "30.0.3"

    defaultConfig {
        applicationId "com.example.medilyf"
        minSdkVersion 16
        targetSdkVersion 30
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
}
apply plugin: 'com.android.application'
apply plugin: 'com.google.gms.google-services'
dependencies {

    implementation platform('com.google.firebase:firebase-bom:28.0.1')
    implementation 'com.google.firebase:firebase-analytics'
    implementation 'androidx.appcompat:appcompat:1.3.0'
    implementation 'com.google.android.material:material:1.3.0'
    implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
    implementation 'com.google.firebase:firebase-database:20.0.0'
    implementation 'org.jetbrains:annotations:15.0'
    testImplementation 'junit:junit:4.13.2'
    androidTestImplementation 'androidx.test.ext:junit:1.1.2'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0'
    implementation 'com.airbnb.android:lottie:3.4.1'
    implementation 'androidx.viewpager2:viewpager2:1.0.0'
}