我创建了一个MapView，在其中使用数据库中的经度和纬度调用绘制了多个标记。
现在，我要在单击此标记时显示底页并在工作表上显示特定数据。我从这里Slide in view from bottom over Google Map on Marker click
获得了一些关于底片的参考但是实现本文后，我得到一个错误
错误是
E/AndroidRuntime: FATAL EXCEPTION: main
Process: part.time.job.v2, PID: 4236
java.lang.NullPointerException: Attempt to invoke virtual method 'void com.google.android.material.bottomsheet.BottomSheetBehavior.setPeekHeight(int)' on a null object reference
at part.time.job.v2.LabourFragment.onCreateView(LabourFragment.java:115)
这是我的JAVA代码
package part.time.job.v2;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.graphics.Color;
import android.graphics.drawable.ColorDrawable;
import android.location.Location;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentTransaction;
import com.google.android.gms.location.FusedLocationProviderClient;
import com.google.android.gms.location.LocationServices;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.MapView;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.model.BitmapDescriptorFactory;
import com.google.android.gms.maps.model.CameraPosition;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.Marker;
import com.google.android.gms.maps.model.MarkerOptions;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.OnSuccessListener;
import com.google.android.gms.tasks.Task;
import com.google.android.libraries.places.api.Places;
import com.google.android.libraries.places.api.model.Place;
import com.google.android.libraries.places.api.model.PlaceLikelihood;
import com.google.android.libraries.places.api.net.FindCurrentPlaceRequest;
import com.google.android.libraries.places.api.net.FindCurrentPlaceResponse;
import com.google.android.libraries.places.api.net.PlacesClient;
import com.google.android.material.bottomnavigation.BottomNavigationView;
import com.google.android.material.bottomsheet.BottomSheetBehavior;
import com.google.firebase.firestore.CollectionReference;
import com.google.firebase.firestore.FirebaseFirestore;
import com.google.firebase.firestore.QueryDocumentSnapshot;
import com.google.firebase.firestore.QuerySnapshot;
import com.google.maps.android.ui.IconGenerator;
import java.util.Arrays;
import java.util.List;
import model.Jobpost;
import static com.android.volley.VolleyLog.TAG;
/**
* A simple {@link Fragment} subclass.
*/
public class LabourFragment extends Fragment implements OnMapReadyCallback {
private GoogleMap mGoogleMap;
private MapView mMapview;
private int STORAGE_PERMISSION_CODE = 1;
private CameraPosition mCameraPosition;
private FusedLocationProviderClient mFusedLocationProviderClient;
private final LatLng mDefaultLocation = new LatLng(-33.8523341, 151.2106085);
private static final int DEFAULT_ZOOM = 15;
private static final int PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION = 1;
private boolean mLocationPermissionGranted;
private Location mLastKnownLocation;
Dialog myDialog;
private BottomSheetBehavior bottomSheetBehavior;
private View bottomSheet;
// Keys for storing activity state.
private static final String KEY_CAMERA_POSITION = "camera_position";
private static final String KEY_LOCATION = "location";
// Used for selecting the current place.
private static final int M_MAX_ENTRIES = 5;
private String[] mLikelyPlaceNames;
private String[] mLikelyPlaceAddresses;
private List[] mLikelyPlaceAttributions;
private LatLng[] mLikelyPlaceLatLngs;
private PlacesClient mPlacesClient;
public LabourFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
if (savedInstanceState != null) {
mLastKnownLocation = savedInstanceState.getParcelable(KEY_LOCATION);
mCameraPosition = savedInstanceState.getParcelable(KEY_CAMERA_POSITION);
}
// Inflate the layout for this fragment
View view= inflater.inflate(R.layout.fragment_labour, container, false);
// myDialog = new Dialog(getActivity());
bottomSheet = view.findViewById(R.id.bottom_sheet);
bottomSheetBehavior = BottomSheetBehavior.from(bottomSheet); //error occur on this line
bottomSheetBehavior.setPeekHeight(200);
bottomSheetBehavior.setHideable(true);
bottomSheetBehavior.setState(BottomSheetBehavior.STATE_HIDDEN);
Places.initialize(getActivity(), getString(R.string.google_maps_key));
mPlacesClient = Places.createClient(getActivity());
mFusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(getActivity());
return view;
}
@Override
public void onSaveInstanceState(Bundle outState) {
if (mGoogleMap != null) {
outState.putParcelable(KEY_CAMERA_POSITION, mGoogleMap.getCameraPosition());
outState.putParcelable(KEY_LOCATION, mLastKnownLocation);
super.onSaveInstanceState(outState);
}
}
@Override
public void onViewCreated(@NonNull View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
mMapview = (MapView) view.findViewById(R.id.mapView);
if (mMapview!=null){
mMapview.onCreate(null);
mMapview.onResume();
mMapview.getMapAsync(this);
}
}
@Override
public void onMapReady(final GoogleMap googleMap) {
mGoogleMap=googleMap;
FirebaseFirestore mDatabase = FirebaseFirestore.getInstance();
CollectionReference mOrderRef = mDatabase.collection("Job Post1");
mOrderRef.get().addOnSuccessListener(new OnSuccessListener<QuerySnapshot>() {
@Override
public void onSuccess(QuerySnapshot queryDocumentSnapshots) {
for(QueryDocumentSnapshot documentSnapshot : queryDocumentSnapshots) {
if(documentSnapshot.contains("lat") && documentSnapshot.contains("lon")) {
String lat = (String) documentSnapshot.get("lat");
String lon = (String) documentSnapshot.get("lon");
final String title = (String) documentSnapshot.get("title");
final String jobdate = (String) documentSnapshot.get("jobdate");
final String time = (String) documentSnapshot.get("time");
if(lat != null && lon != null && !lat.isEmpty() && !lon.isEmpty()) {
double latitude = Double.parseDouble(lat.trim());
double longitude = Double.parseDouble(lon.trim());
IconGenerator iconGen = new IconGenerator(getActivity());
googleMap.addMarker(new MarkerOptions().position(new LatLng(latitude, longitude)).icon(BitmapDescriptorFactory.fromBitmap(iconGen.makeIcon(title))));
googleMap.animateCamera(CameraUpdateFactory.newLatLngZoom(new LatLng(latitude, longitude), 18.0f));
googleMap.setOnMarkerClickListener(new GoogleMap.OnMarkerClickListener() {
@Override
public boolean onMarkerClick(Marker marker) {
updateBottomSheetContent(marker);
return false;
}
});
googleMap.setOnMapClickListener(new GoogleMap.OnMapClickListener() {
@Override
public void onMapClick(LatLng latLng) {
bottomSheetBehavior.setState(BottomSheetBehavior.STATE_HIDDEN);
}
});
}
}
}
}
});
}
private void updateBottomSheetContent(Marker marker) {
TextView name = (TextView) bottomSheet.findViewById(R.id.detail_name);
name.setText(marker.getTitle());
bottomSheetBehavior.setState(BottomSheetBehavior.STATE_COLLAPSED);
}
}
xml视图
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="part.time.job.v2.LabourFragment">
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="@+id/bottom_navigation_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
app:itemBackground="@color/purple"
app:itemIconTint="@color/white"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:menu="@menu/nav_items"
tools:ignore="MissingConstraints" />
<com.google.android.gms.maps.MapView
android:id="@+id/mapView"
android:layout_width="match_parent"
android:layout_height="675dp"
tools:ignore="MissingConstraints" />
</androidx.constraintlayout.widget.ConstraintLayout>
bottom_sheet xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:fitsSystemWindows="true">
<android.support.v4.widget.NestedScrollView android:id="@+id/bottom_sheet"
android:layout_width="match_parent" android:layout_height="550dp"
android:background="@android:color/white" android:clipToPadding="true"
app:layout_behavior="android.support.design.widget.BottomSheetBehavior">
<TextView android:id="@+id/detail_name" android:layout_width="0dp"
android:layout_height="wrap_content" android:layout_margin="25dp"
android:layout_weight="3" android:gravity="center_vertical"
android:textAppearance="?android:textAppearanceLarge" />
</android.support.v4.widget.NestedScrollView>
</androidx.coordinatorlayout.widget.CoordinatorLayout>
您的xml中没有具有“ R.id.bottom_sheet” id的视图，但是您试图通过findViewbyIdId（）获取视图，这就是为什么bottomSheet变量具有null值，而且bottomsheetbehaviour值也为null并产生null指针的原因尝试访问其上的任何方法时发生异常。在您的情况下，以下行：
bottomSheetBehavior.setPeekHeight(200);