如何从Firebase检索数据并将其设置为图表的字符串和整数

Question

[早上/下午/晚上好，我只需要帮助，如何将字符串和值的数据从Firebase更改为代码或图表。我目前正在使用如图所示的预设值（字符串“ skyobject”和int“ 500,300,600,123”，并希望使用图像中显示的Firebase中的数据。感谢您的帮助，我是Android Studio的新手，所以我非常感谢我能提供的任何帮助。在此先感谢您为我提供帮助的那些人

public class MainActivity extends AppCompatActivity {
    AnyChartView anyChartView;
    Button btn;
    DatabaseReference reff;


    String [] skyobject = {"sun","moon","stars","planets"};
    int[] datas = {500,300,600,123};


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

        anyChartView =( AnyChartView) findViewById(R.id.any_chart_view);
        setupPieChart();


    }
    public void setupPieChart() {
        Pie pie = AnyChart.pie();
        List<DataEntry> dataEntries = new ArrayList<>();

        for (int i=0;i<skyobject.length;i++){
            dataEntries.add(new ValueDataEntry(skyobject[i],datas[i]));


        }
        pie.data(dataEntries);
        anyChartView.setChart(pie);

    }
}

带有给定代码@Alex Mamo的已编辑代码

package com.javapapers.androidchartapp;

import android.os.Bundle;
import android.util.Log;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;

import com.anychart.AnyChart;
import com.anychart.AnyChartView;
import com.anychart.chart.common.dataentry.DataEntry;
import com.anychart.chart.common.dataentry.ValueDataEntry;
import com.anychart.charts.Pie;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.ValueEventListener;
import com.javapapers.androidchartapp.R;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {
    AnyChartView anyChartView;

    DatabaseReference rootRef;


    String [] skyobject = {"sun","moon","stars","planets"};
    int[] datas = {500,300,600,123};


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
        ValueEventListener valueEventListener = new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                for(DataSnapshot ds : dataSnapshot.getChildren()) {
                    String key = ds.getKey();
                    String name = ds.getValue(String.class);
                    Log.d("TAG", key + ": " + name);
                }
            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {
                Log.d(TAG, databaseError.getMessage()); //Don't ignore errors!
            }
        };
        rootRef.addListenerForSingleValueEvent(valueEventListener);
        anyChartView = findViewById(R.id.any_chart_view);
        setupPieChart();


    }
    public void setupPieChart() {
        Pie pie = AnyChart.pie();
        List<DataEntry> dataEntries = new ArrayList<>();

        for (int i=0;i<skyobject.length;i++){
            dataEntries.add(new ValueDataEntry(skyobject[i],datas[i]));

        }
        pie.data(dataEntries);
        anyChartView.setChart(pie);

    }

这是Logcat中的错误

2020-03-25 12:12:47.695 14164-14257/com.javapapers.androidchartapp D/OpenGLRenderer: HWUI GL Pipeline
2020-03-25 12:12:47.698 14164-14203/com.javapapers.androidchartapp V/FA: Connection attempt already in progress
2020-03-25 12:12:47.708 14164-14203/com.javapapers.androidchartapp V/FA: Activity resumed, time: 23657209
2020-03-25 12:12:47.754 14164-14164/com.javapapers.androidchartapp D/AndroidRuntime: Shutting down VM
2020-03-25 12:12:47.761 14164-14164/com.javapapers.androidchartapp E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.javapapers.androidchartapp, PID: 14164
    java.lang.RuntimeException: Uncaught exception in Firebase Database runloop (3.0.0). Please report to [email protected]
        at com.google.firebase.database.android.AndroidPlatform$1$1.run(com.google.firebase:firebase-database@@16.0.4:98)
        at android.os.Handler.handleCallback(Handler.java:790)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:164)
        at android.app.ActivityThread.main(ActivityThread.java:6494)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
     Caused by: java.lang.NoClassDefFoundError: Failed resolution of: Lcom/google/firebase/FirebaseApp$IdTokenListener;
        at com.google.firebase.database.android.AndroidPlatform.newAuthTokenProvider(com.google.firebase:firebase-database@@16.0.4:112)
        at com.google.firebase.database.core.Context.ensureAuthTokenProvider(com.google.firebase:firebase-database@@16.0.4:246)
        at com.google.firebase.database.core.Context.initServices(com.google.firebase:firebase-database@@16.0.4:98)
        at com.google.firebase.database.core.Context.freeze(com.google.firebase:firebase-database@@16.0.4:77)
        at com.google.firebase.database.core.RepoManager.createLocalRepo(com.google.firebase:firebase-database@@16.0.4:92)
        at com.google.firebase.database.core.RepoManager.createRepo(com.google.firebase:firebase-database@@16.0.4:42)
        at com.google.firebase.database.FirebaseDatabase.ensureRepo(com.google.firebase:firebase-database@@16.0.4:357)
        at com.google.firebase.database.FirebaseDatabase.getReference(com.google.firebase:firebase-database@@16.0.4:188)
        at com.javapapers.androidchartapp.MainActivity.onCreate(MainActivity.java:38)
        at android.app.Activity.performCreate(Activity.java:7009)
        at android.app.Activity.performCreate(Activity.java:7000)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1214)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2731)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2856)
        at android.app.ActivityThread.-wrap11(Unknown Source:0)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:164) 
        at android.app.ActivityThread.main(ActivityThread.java:6494) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807) 
     Caused by: java.lang.ClassNotFoundException: Didn't find class "com.google.firebase.FirebaseApp$IdTokenListener" on path: DexPathList[[zip file "/data/app/com.javapapers.androidchartapp-fqstuAIPXt2RuaMTnfZoLA==/base.apk"],nativeLibraryDirectories=[/data/app/com.javapapers.androidchartapp-fqstuAIPXt2RuaMTnfZoLA==/lib/x86, /system/lib, /vendor/lib]]
        at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:125)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:379)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:312)
        at com.google.firebase.database.android.AndroidPlatform.newAuthTokenProvider(com.google.firebase:firebase-database@@16.0.4:112) 
        at com.google.firebase.database.core.Context.ensureAuthTokenProvider(com.google.firebase:firebase-database@@16.0.4:246) 
        at com.google.firebase.database.core.Context.initServices(com.google.firebase:firebase-database@@16.0.4:98) 
        at com.google.firebase.database.core.Context.freeze(com.google.firebase:firebase-database@@16.0.4:77) 
        at com.google.firebase.database.core.RepoManager.createLocalRepo(com.google.firebase:firebase-database@@16.0.4:92) 
        at com.google.firebase.database.core.RepoManager.createRepo(com.google.firebase:firebase-database@@16.0.4:42) 
        at com.google.firebase.database.FirebaseDatabase.ensureRepo(com.google.firebase:firebase-database@@16.0.4:357) 
        at com.google.firebase.database.FirebaseDatabase.getReference(com.google.firebase:firebase-database@@16.0.4:188) 
        at com.javapapers.androidchartapp.MainActivity.onCreate(MainActivity.java:38) 
        at android.app.Activity.performCreate(Activity.java:7009) 
        at android.app.Activity.performCreate(Activity.java:7000) 
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1214) 
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2731) 
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2856) 
        at android.app.ActivityThread.-wrap11(Unknown Source:0) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589) 
        at android.os.Handler.dispatchMessage(Handler.java:106) 
        at android.os.Looper.loop(Looper.java:164) 
        at android.app.ActivityThread.main(ActivityThread.java:6494) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807) 
2020-03-25 12:12:47.882 14164-14203/com.javapapers.androidchartapp I/FA: Tag Manager is not found and thus will not be used
2020-03-25 12:12:48.210 14164-14203/com.javapapers.androidchartapp V/FA: Connection attempt already in progress
2020-03-25 12:12:48.210 14164-14203/com.javapapers.androidchartapp V/FA: Connection attempt already in progress

我数据库的图像click here

饼图输出click here的图像

用给定的代码编辑，TAG click here出现错误

Answer 1

要获取这些属性的键和值，请使用以下代码行：

DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
ValueEventListener valueEventListener = new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        for(DataSnapshot ds : dataSnapshot.getChildren()) {
            String key = ds.getKey();
            String name = ds.getValue(String.class);
            Log.d("TAG", key + ": " + name);
        }
    }

    @Override
    public void onCancelled(@NonNull DatabaseError databaseError) {
        Log.d(TAG, databaseError.getMessage()); //Don't ignore errors!
    }
};
rootRef.addListenerForSingleValueEvent(valueEventListener);

您的logcat中的结果将是：

Moon: 300
Planets: 123
Stars: 600
Sun:  500