即使在代码中手动设置位置后,标记也不会显示在地图上
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【中文标题】即使在代码中手动设置位置后,标记也不会显示在地图上【英文标题】:Marker not showing up on map even after setting location manually in code 【发布时间】:2019-12-22 03:36:22 【问题描述】:我正在尝试从 Firebase 数据库中检索双精度值(经度和纬度)并将其显示在地图上。问题是标记没有显示在地图上,我认为这是一个数据库错误,但即使我在代码本身中添加纬度和经度,标记也没有显示(如下所示)。请帮助我,谢谢!
我尝试了从数据库中检索数据的不同方法以及添加标记的不同方法。
MapsActivity.java
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.FragmentActivity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.database.ChildEventListener;
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;
public class MapsActivity extends FragmentActivity implements OnMapReadyCallback
private GoogleMap mMap;
private FirebaseAuth mAuth;
//String value_latitude = "0";
// String value_longitue = "0";
double longi = 0;
double lati = 0;
// String message = "BUS1";
Button Refreshh;
Double latitude = 0.0;
Double longitdue = 0.0;
String vali = "BUS1";
String message = "BUS1";
Button Backkk;
private FirebaseDatabase mDatabase = FirebaseDatabase.getInstance();
private DatabaseReference mDatabaseReference = mDatabase.getReference();
@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_maps);
//Intent intent = getIntent();
message = getIntent().getExtras().getString("arg");
vali = message;
// Obtain the SupportMapFragment and get notified when the map is ready to be used.
//vali = message;
//Log.d("vali", vali);
/**
*
* Manipulates the map once available.
* This callback is triggered when the map is ready to be used.
* This is where we can add markers or lines, add listeners or move the camera. In this case,
* we just add a marker near Sydney, Australia.
* If Google Play services is not installed on the device, the user will be prompted to install
* it inside the SupportMapFragment. This method will only be triggered once the user has
* installed Google Play services and returned to the app.
*/
@Override
public void onMapReady(GoogleMap googleMap)
mMap = googleMap;
mMap.clear();
mDatabaseReference.child("Locations").child(vali).addChildEventListener(new ChildEventListener()
@Override
public void onChildAdded(@NonNull DataSnapshot dataSnapshot, String prevChildKey)
LatLng newLocation = new LatLng(
dataSnapshot.child("latitude").getValue(Long.class),
dataSnapshot.child("longitude").getValue(Long.class)
);
LatLng sydney = new LatLng(13.0640934, 80.2501135);
mMap.addMarker(new MarkerOptions().position(sydney)
.title("Marker in Sydney"));
mMap.moveCamera(CameraUpdateFactory.newLatLng(sydney));
@Override
public void onChildChanged(@NonNull DataSnapshot dataSnapshot, String prevChildKey)
@Override
public void onChildRemoved(@NonNull DataSnapshot dataSnapshot)
@Override
public void onChildMoved(@NonNull DataSnapshot dataSnapshot, String prevChildKey)
@Override
public void onCancelled(@NonNull DatabaseError databaseError)
);
我的 Logcat:
2019-08-15 23:03:09.134 4869-5490/? E/...lback.CallbackFuture: Timed out waiting for result!
2019-08-15 23:03:09.135 4869-5490/? E/AmazonKindle.com.amazon.kindle.services.authentication.MAPTokenCache: [WebRequestManager-webserviceRequest2-thread-1]: Retrieving of token: com.amazon.dcp.sso.token.cookie.xmainAndXabcCookies failed
java.util.concurrent.TimeoutException: Timed out waiting for result!
at com.amazon.identity.auth.device.callback.CallbackFuture.get(CallbackFuture.java:170)
at com.amazon.identity.auth.device.callback.CallbackFuture.get(CallbackFuture.java:26)
at com.amazon.kindle.services.authentication.MAPTokenCache.retrieveToken(MAPTokenCache.java:378)
at com.amazon.kindle.services.authentication.MAPTokenCache.fetchTokenManagementToken(MAPTokenCache.java:338)
at com.amazon.kindle.services.authentication.MAPTokenCache.fetchValue(MAPTokenCache.java:263)
at com.amazon.kindle.services.authentication.MAPTokenCache.getValue(MAPTokenCache.java:156)
at com.amazon.kindle.services.authentication.AccountHoldersKt.getToken(AccountHolders.kt:119)
at com.amazon.kindle.services.authentication.KindleAuthenticationManager.getToken(KindleAuthenticationManager.kt:185)
at com.amazon.kindle.krx.application.DeviceInformation.getXmainXacbCookieForDevicePfm(DeviceInformation.java:137)
at com.amazon.kcp.library.customerbenefits.CustomerBenefitsWebRequest.getHeaders(CustomerBenefitsWebRequest.java:102)
at com.amazon.kindle.webservices.BaseWebRequestExecutor.connect(BaseWebRequestExecutor.java:536)
at com.amazon.kindle.webservices.BaseWebRequestExecutor.openConnection(BaseWebRequestExecutor.java:200)
at com.amazon.kindle.webservices.BaseWebRequestExecutor.execute(BaseWebRequestExecutor.java:121)
at com.amazon.kindle.webservices.WebRequestManager$WebRequestTask.executeRequest(WebRequestManager.java:125)
at com.amazon.kindle.webservices.WebRequestManager$WebRequestTask.run(WebRequestManager.java:98)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
at java.lang.Thread.run(Thread.java:764)
【问题讨论】:
请将您的数据库结构添加为 JSON 文件或至少作为屏幕截图。 【参考方案1】:您在 ChildEventListener 中添加标记,onChildAdded()
仅在每个现有子项以及新子项添加到您正在收听的引用中时调用。 因此,如果您的引用没有任何子项,则不会调用它。
检查您的 FirebaseReference,您可能访问了错误的孩子。 或者您可能使用了错误的侦听器,如果您将代码移出侦听器,您会看到它确实显示了标记。 如果要获取子引用的值,则必须添加 ValueEventListener:
ref.addValueEventListener(new ValueEventListener()
@Override
public void onDataChange(DataSnapshot dataSnapshot)
Post post = dataSnapshot.getValue(Post.class);
System.out.println(post);
@Override
public void onCancelled(DatabaseError databaseError)
System.out.println("The read failed: " + databaseError.getCode());
);
【讨论】:
Firebase 数据库中有一个参考,但由于某种原因该标记未显示在地图上。即使我直接在代码中添加坐标以上是关于即使在代码中手动设置位置后,标记也不会显示在地图上的主要内容,如果未能解决你的问题,请参考以下文章
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