Question

我有一个firebase数据库，我正在存储一个数字作为项目的索引。我使用我的数据库类

访问它

public class IndexCount {
    private String Streaming;
    public IndexCount(String Streaming){
    this.Streaming = Streaming;
}

public void databaseIndexCounter( ){

    FirebaseDatabase db = FirebaseDatabase.getInstance();
    DatabaseReference dbref = db.getReference().child("Apps").child("IndexCount");
    dbref.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            Integer Stream = dataSnapshot.child("Streaming").getValue(Integer.class);
            Streaming = Stream.toString();
            Log.i("streamcount: ",Streaming);
        }
    }
}

我想访问此类之外的Streaming字符串，并在我的主活动中使用它来填充textview。我怎么能做到这一点？我以为从我的主要活动中调用这个就可以了。

String streamcounter = new String();
IndexCount indexcount = new IndexCount(streamcounter);
tvstreaming = (TextView)view.findViewById(R.id.streamcount);

indexcount.databaseIndexCounter();
Log.i("stream count: ",streamcounter);
tvstreaming.setText(streamcounter);

但日志不会触发，所以我假设我的代码是错误的lol。谢谢你们

Answer 1

onDataChange将在另一个线程（不是主线程）中执行，所以你需要等到它完成它的工作，然后做你想要的。

public class IndexCount {
    private String Streaming;
    public IndexCount(String Streaming){
    this.Streaming = Streaming;
}

public void databaseIndexCounter( ){

    FirebaseDatabase db = FirebaseDatabase.getInstance();
    DatabaseReference dbref = db.getReference().child("Apps").child("IndexCount");
    dbref.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            Integer Stream = dataSnapshot.child("Streaming").getValue(Integer.class);
            Streaming = Stream.toString();
            Log.i("streamcount: ",Streaming);
            // call it here 
            nextStep();
        }
    }
}
public void nextStep(){
Log.i("stream count: ",streamcounter);
tvstreaming.setText(streamcounter);
}

并从您的主要活动

String streamcounter = new String();
IndexCount indexcount = new IndexCount(streamcounter);
tvstreaming = (TextView)view.findViewById(R.id.streamcount);

indexcount.databaseIndexCounter();

在其类之外使用来自firebase数据库的String

1 个答案: