Android 应用未实时连接到 Firebase 数据库

Question

我看不到我错过了什么。我想要的只是从 2 个编辑文本框中输入文本，然后单击保存按钮以更新到数据库。请参阅下文了解更多信息，非常感谢您的帮助。该数据库非常简单，仅称为“用户”，如果我可以提供任何其他信息，请告诉我。谢谢。

activity_main.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"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <EditText
        android:id="@+id/inputFirstName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        android:hint="enter your first name"
        android:layout_margin="10dp"
        />

    <EditText
        android:id="@+id/inputLastName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="10dp"
        android:layout_marginStart="16dp"
        android:layout_marginTop="16dp"
        android:hint="enter your last name"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/inputFirstName" />

    <Button android:id="@+id/saveButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="save"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"

        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="@id/inputLastName" />

</androidx.constraintlayout.widget.ConstraintLayout>

MainActivity.kt

package com.example.firedemo
import android.annotation.SuppressLint
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.os.Parcelable
import android.text.TextUtils
import android.widget.Button
import android.widget.EditText
import com.google.firebase.database.DatabaseReference
import com.google.firebase.database.FirebaseDatabase

import com.google.firebase.database.IgnoreExtraProperties
import kotlinx.android.synthetic.main.activity_main.*

@IgnoreExtraProperties
data class user(
    var firstname: String,
    var lastname: String
)

private lateinit var dbReference: DatabaseReference
private lateinit var firebaseDatabase: FirebaseDatabase
private var userId: String = ""

//EditText
@SuppressLint("StaticFieldLeak")
private lateinit var firstNameEt: EditText
@SuppressLint("StaticFieldLeak")
private lateinit var lastNameEt: EditText

//Button
@SuppressLint("StaticFieldLeak")
private lateinit var saveButton: Button


 abstract class MainActivity() : AppCompatActivity(), Parcelable {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        firebaseDatabase = FirebaseDatabase.getInstance()
        dbReference = firebaseDatabase.getReference("users")

firstNameEt = findViewById(R.id.inputFirstName)
        lastNameEt = findViewById(R.id.inputLastName)


        userId = dbReference.push().key.toString()

        saveButton.setOnClickListener{
            val firstname: String = firstNameEt.text.toString()
            val lastname: String = lastNameEt.text.toString()
            if(TextUtils.isEmpty(userId)){
                createUser(firstname, lastname)
            } else{
                null
            }

        }

    }

    private fun createUser(firstname: String, lastname: String){

    // Write a message to the database

        val user = user(firstname, lastname)
        dbReference.child(userId).setValue(user)
    }


    }

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.firedemo">
    <uses-permission android:name="android.permission.INTERNET"/>

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.Firedemo">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

build.gradle

plugins {
    id 'com.android.application'
    id 'com.google.gms.google-services'
    id 'kotlin-android'
    id 'kotlin-android-extensions'

}

android {
    compileSdkVersion 30
    buildToolsVersion "30.0.3"

    defaultConfig {
        applicationId "com.example.firedemo"
        minSdkVersion 23
        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
    }
    kotlinOptions {
        jvmTarget = '1.8'
    }
}

dependencies {

    implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
    implementation 'androidx.core:core-ktx:1.3.2'
    implementation 'androidx.appcompat:appcompat:1.2.0'
    implementation 'com.google.android.material:material:1.3.0'
    implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
    implementation 'com.google.firebase:firebase-database:19.7.0'
    testImplementation 'junit:junit:4.+'
    androidTestImplementation 'androidx.test.ext:junit:1.1.2'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0'
    implementation platform('com.google.firebase:firebase-bom:26.7.0')

    implementation 'com.google.firebase:firebase-analytics-ktx'

}