带有Firebase的Android:DataSnapshot.getValue()引发java.lang.IllegalArgumentException [英] Android with Firebase : DataSnapshot.getValue() throws java.lang.IllegalArgumentException

问题描述

我正在从Firebase实时数据库中编写和读取类User.这是用户类:

I am writing and reading class User from Firebase realtime database. This is User class :

public class User {

    public String name;
    public int number;
    public String title;
    public String company;
    public String location;
    public Bitmap image;
    public String name_title_company_location;

    public User() {
        // Default constructor required for calls to DataSnapshot.getValue(User.class)
    }

    public User(String name, int number, String title, String company, String location, Bitmap image) {
        this.name = name;
        this.number = number;
        this.title = title;
        this.company = company;
        this.location = location;
        this.image = image;
        this.name_title_company_location = name + "_" + title + "_" +company + "_" + location;
    }

这是我的Firebase实时数据库:

This is my Firebase realtime database:

users
  0
    company: "Indifair"
    image
    location: "Bangalore"
    name: "Anupam Singh"
    name_title_company_location: "Anupam Singh_Engineer_Indifair_Bangalore"
    number: 956156494
    title: "Engineer"

这段代码抛出错误:

DatabaseReference mDatabase = FirebaseDatabase.getInstance().getReference();
EditText t1 = (EditText) findViewById(R.id.editText10);
EditText t2 = (EditText) findViewById(R.id.editText11);
EditText t3 = (EditText) findViewById(R.id.editText13);
EditText t4 = (EditText) findViewById(R.id.editText14);

String s1 = t1.getText().toString();
String s2 = t2.getText().toString();
String s3 = t3.getText().toString();
String s4 = t4.getText().toString();

mDatabase.child("users").orderByChild("name_title_company_location")
        .equalTo(s1 + "_" + s2 + "_" + s3 + "_" + s4)
        .addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {

                    User user  = dataSnapshot.getValue(User.class);
                    //ImageView im = (ImageView) findViewById(R.id.imageView);
                    //TextView tv1 = (TextView) findViewById(R.id.textView3);
                    //TextView tv2 = (TextView) findViewById(R.id.textView5);
                    ///im.setImageBitmap(user.image);
                    ///tv1.setText(user.name);
                    ///tv2.setText(user.number);


            }

            public void onCancelled(DatabaseError databaseError) {
                // Getting Post failed, log a message
                //Log.w(TAG, "loadPost:onCancelled", databaseError.toException());
            }

        });

我收到此错误:

    java.lang.IllegalArgumentException: Service not registered: com.google.android.gms.measurement.internal.zzjc@45abe13
    at android.app.LoadedApk.forgetServiceDispatcher(LoadedApk.java:1105)
    at android.app.ContextImpl.unbindService(ContextImpl.java:1873)
    at android.content.ContextWrapper.unbindService(ContextWrapper.java:562)
    at com.google.android.gms.common.stats.ConnectionTracker.unbindService(Unknown Source)
    at com.google.android.gms.measurement.internal.zzik.zzah(com.google.android.gms:play-services-measurement-impl@@17.2.0:240)
    at com.google.android.gms.measurement.internal.zzik.zzak(com.google.android.gms:play-services-measurement-impl@@17.2.0:257)
    at com.google.android.gms.measurement.internal.zzik.zzc(com.google.android.gms:play-services-measurement-impl@@17.2.0:319)
    at com.google.android.gms.measurement.internal.zzij.zza(com.google.android.gms:play-services-measurement-impl@@17.2.0:2)
    at com.google.android.gms.measurement.internal.zzai.run(com.google.android.gms:play-services-measurement-impl@@17.2.0:7)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:422)
    at java.util.concurrent.FutureTask.run(FutureTask.java:237)
    at com.google.android.gms.measurement.internal.zzfy.run(com.google.android.gms:play-services-measurement-impl@@17.2.0:20)

当我注释掉 User user = dataSnapshot.getValue(User.class); 时，错误消失了.

When I comment out User user = dataSnapshot.getValue(User.class); the error is gone.

出什么问题了?

推荐答案

对Firebase数据库执行查询时，可能会有多个结果.因此，快照包含这些结果的列表.即使只有一个结果，快照也会包含一个结果的列表.

When you execute a query against the Firebase Database, there will potentially be multiple results. So the snapshot contains a list of those results. Even if there is only a single result, the snapshot will contain a list of one result.

因此，您的 onDataChange 需要处理以下事实，即 DataSnapshot 可以包含多个用户.您可以像这样通过遍历 dataSnapshot.getChildren()来轻松地做到这一点:

So your onDataChange needs to handle the fact that the DataSnapshot can contain multiple users. You can easily do this by looping over the dataSnapshot.getChildren() like this:

mDatabase.child("users").orderByChild("name_title_company_location")
    .equalTo(s1 + "_" + s2 + "_" + s3 + "_" + s4)
    .addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            for (DataSnapshot userSnapshot: dataSnapshot.getChildren) {
                User user = userSnapshot.getValue(User.class);
                ...
            }
        }

这篇关于带有Firebase的Android:DataSnapshot.getValue()引发java.lang.IllegalArgumentException的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！