我只是检索信息并在地图上以标记的形式显示它。我是否有可能获得显示的标记数。
btnValidate = (Button)findViewById(R.id.validate);
btnValidate.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//Clear map from all markers
mMap.clear();
//Filter markers by disease
disease = String.valueOf(spnDisease.getSelectedItem()).toLowerCase();
location = String.valueOf(spnLocation.getSelectedItem());
Query dbQuery = FirebaseDatabase.getInstance().getReference().child("diseaseReported").orderByChild("nameReportedAtReportedOn").equalTo(disease+location+txtDate.getText());
dbQuery.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
Log.d("v1", dataSnapshot.toString());
Map m = dataSnapshot.getValue(Map.class);
double lat = m.getLat();
double lng = m.getLng();
String reportedAt = m.getReportedAt();
String reportedOn = m.getReportedOn();
String name = m.getName();
String snippetText = "Reported on: " + reportedOn;
LatLng c = new LatLng(lat, lng);
mMap.addMarker(new MarkerOptions().position(c).title("Disease reported: " + name).snippet(snippetText).icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_GREEN)));
}
@Override
public void onChildChanged(DataSnapshot dataSnapshot, String s) {
}
@Override
public void onChildRemoved(DataSnapshot dataSnapshot) {
}
@Override
public void onChildMoved(DataSnapshot dataSnapshot, String s) {
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
});
}
请参阅所附的代码和图片。该代码表示从 firebase 检索到的信息。
声明计数器:
int markersCount = 0;
并ChildEventListener
用 a替换你的ValueEventListener
,在forEach
循环中增加计数器:
int markersCount = 0;
Query dbQuery = FirebaseDatabase.getInstance().getReference().child("diseaseReported").orderByChild("nameReportedAtReportedOn").equalTo(disease+location+txtDate.getText());
dbQuery.addValueEventListener(new ValueEventListener(){
@Override
public void onDataChange(DataSnapshot snapshot) {
for(DataSnapshot dataSnapshot : snapshot.getChildren())
{
Log.d("v1", dataSnapshot.toString());
Map m = dataSnapshot.getValue(Map.class);
double lat = m.getLat();
double lng = m.getLng();
String reportedAt = m.getReportedAt();
String reportedOn = m.getReportedOn();
String name = m.getName();
String snippetText = "Reported on: " + reportedOn;
LatLng c = new LatLng(lat, lng);
mMap.addMarker(new MarkerOptions().position(c).title("Disease reported: " + name).snippet(snippetText).icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_GREEN)));
markersCount++;
}
Log.i("Markers Count", "Total Markers="+markersCount);
}
});
另请注意,我在循环完成后打印了计数。
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