从返回空的绑定服务访问数组列表<字符串>

Question

我正在访问服务的marraylist变量，尽管它是由Firebase中的数据初始化的，但在Activity中返回空的marraylist，该变量是通过从Firebase数据库中获取数据在服务数组中初始化的，在toast中，我将从Firebase获取数据到marraylist，但当我试图在活动中访问变量时，它会返回我的空ArrayList。

绑定到服务的我的类是

public class ProfileList extends AppCompatActivity  
implements View.OnClickListener {
private FirebaseAuth mAuth;
Dialog Mydialog;
private FirebaseAuth.AuthStateListener authStateListener;
public DatabaseReference db;
public String userid;
FirebaseUser firebaseUser;
public String iamlog="hy";
List<String> listSt;
String snapdata,log;
ArrayList<String> m1arraylist = new ArrayList <String>();
RecyclerView recyclerView;
public ProfileService myservice;
Intent intent;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.profilelist);
db = FirebaseDatabase.getInstance().getReference().child("users");
recyclerView = (RecyclerView) findViewById(R.id.recyclerview);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
Button button2 = (Button) findViewById(R.id.button2);
mAuth = FirebaseAuth.getInstance();
userid = mAuth.getCurrentUser().getUid();
db = db.child(userid);
Uri uri = Uri.parse(String.valueOf(db));
Log.e(iamlog,String.valueOf(uri));
Intent Profileserviceint = new Intent(this, ProfileService.class);
Profileserviceint.putExtra("dbrefuri",String.valueOf(uri));
bindService(Profileserviceint, connection, Context.BIND_AUTO_CREATE);
}


ServiceConnection connection = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
Localservice localservice = (Localservice) service;
myservice=localservice.getservice();
m1arraylist=myservice.getdata();
recyclerView.setAdapter(new ProgramingAdapter(ProfileList.this,localservice.getservice().marraylist));
Log.e(iamlog,"Profile calss "+ String.valueOf(localservice.getservice().marraylist));
}
@Override
public void onServiceDisconnected(ComponentName name) {
}
};

我的服务等级是

public class ProfileService extends Service {
public DatabaseReference db;
Intent intent;
public String iamlog="hy";
String dbref;
public ArrayList<String> marraylist = new ArrayList<>() ;
public IBinder mbinder = new Localservice();
/**
* Creates an IntentService.  Invoked by your subclass's constructor.
*
* Used to name the worker thread, important only for debugging.
*/

@Nullable
@Override
public IBinder onBind(Intent intent) {
dbref  =intent.getStringExtra("dbrefuri");
return  mbinder;
}
/**
* Creates an IntentService.  Invoked by your subclass's constructor.
*
*/

public     class  Localservice extends Binder
{
public   ProfileService getservice()
{
return ProfileService.this;
}
}
public  ArrayList<String> getdata()
{
db=  FirebaseDatabase.getInstance().getReferenceFromUrl(dbref);
db.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot dataSnapshot2 : dataSnapshot.getChildren())
{
marraylist.add(dataSnapshot2.getKey());
}
Toast toast =  Toast.makeText(ProfileService.this ,String.valueOf(marraylist),Toast.LENGTH_LONG);
toast.show();
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
return marraylist;
}
}

Answer 1

当您调用getData((它启动数据提取，但提取尚未完成。返回的ArrayList中还没有任何项目。一旦数据在内提取

onDataChange(DataSnapshot dataSnapshot) 

数据被添加到列表中。RecyclerView没有看到此更改。

你需要打电话给

notifyDataSetChanged() 

一旦数据被加载。将代码更改为类似的内容

public class ProfileService extends Service {
public DatabaseReference db;
Intent intent;
public String iamlog="hy";
String dbref;
WeakReference<ProfileServiceCallback> profileServiceCallBackRef;
public ArrayList<String> marraylist = new ArrayList<>() ;
public IBinder mbinder = new Localservice();
/**
* Creates an IntentService.  Invoked by your subclass's constructor.
*
* Used to name the worker thread, important only for debugging.
*/

@Nullable
@Override
public IBinder onBind(Intent intent) {
dbref  =intent.getStringExtra("dbrefuri");
return  mbinder;
}
/**
* Creates an IntentService.  Invoked by your subclass's constructor.
*
*/

public     class  Localservice extends Binder
{
public   ProfileService getservice()
{
return ProfileService.this;
}
public void setCallback(ProfileServiceCallBack callback){
profileServiceCallbackRef = new WeakReference<ProfileServiceCallBack>(callback);
}
}
public static interface ProfileServiceCallBack {
public void onDataChanged(List<String> data);
}

public  void getdata()
{
db=  FirebaseDatabase.getInstance().getReferenceFromUrl(dbref);
db.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot dataSnapshot2 : dataSnapshot.getChildren())
{
marraylist.add(dataSnapshot2.getKey());
}
Toast toast =  Toast.makeText(ProfileService.this ,String.valueOf(marraylist),Toast.LENGTH_LONG);
toast.show();
if(profileServiceCallbackRef != null){
ProfileServiceCallback callback = profileServiceCallbackRef.get();
if(callback != null){
profileServiceCallback.onDataChanged(mArrayList);
}
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
}

活动

public class ProfileList extends AppCompatActivity  
implements View.OnClickListener,ProfileServiceCallback {
private FirebaseAuth mAuth;
Dialog Mydialog;
private FirebaseAuth.AuthStateListener authStateListener;
public DatabaseReference db;
public String userid;
FirebaseUser firebaseUser;
public String iamlog="hy";
List<String> listSt;
String snapdata,log;
ArrayList<String> m1arraylist = new ArrayList <String>();
RecyclerView recyclerView;
public ProfileService myservice;
ProgramingAdapter programmingAdapter;
Intent intent;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.profilelist);
db = FirebaseDatabase.getInstance().getReference().child("users");
recyclerView = (RecyclerView) findViewById(R.id.recyclerview);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
programmingAdapter = new ProgrammingAdapter();
recyclerView.setAdapter(programmingAdapter);
recyclerView.setAdapter();
Button button2 = (Button) findViewById(R.id.button2);
mAuth = FirebaseAuth.getInstance();
userid = mAuth.getCurrentUser().getUid();
db = db.child(userid);
Uri uri = Uri.parse(String.valueOf(db));
Log.e(iamlog,String.valueOf(uri));
Intent Profileserviceint = new Intent(this, ProfileService.class);
Profileserviceint.putExtra("dbrefuri",String.valueOf(uri));
bindService(Profileserviceint, connection, Context.BIND_AUTO_CREATE);
}
@Override
public void onDataChanged(List<String> data){
programmingAdapter.setData(data);
programmingAdapter.notifyDatasetChanged(); 
}
ServiceConnection connection = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
Localservice localservice = (Localservice) service;
myservice=localservice.getservice();
myservice.getdata(ProfileList.this);
myservice.setCallback();
Log.e(iamlog,"Profile calss "+ String.valueOf(localservice.getservice().marraylist));
}
@Override
public void onServiceDisconnected(ComponentName name) {
}
};

您需要在ProgrammingAdapter 中添加一个方法

setData(List<String> data){
this.data = data;
notifyDatasetChanged(); 
}