Question

我在我的活动中收到此错误

我正在使用地图fragment在我的google map中展示activity我不知道我做错了我添加了正确的权限

java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Class java.lang.Object.getClass()' on a null object reference
at android.support.v4.app.BackStackRecord.doAddOp(BackStackRecord.java:431)
at android.support.v4.app.BackStackRecord.add(BackStackRecord.java:426)
at android.support.v4.app.FragmentPagerAdapter.instantiateItem(FragmentPagerAdapter.java:103)
at android.support.v4.view.ViewPager.addNewItem(ViewPager.java:1006)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1220)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1088)
at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1614)
at android.view.View.measure(View.java:17562)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5536)
at android.support.design.widget.CoordinatorLayout.onMeasureChild(CoordinatorLayout.java:700)
at android.support.design.widget.HeaderScrollingViewBehavior.onMeasureChild(HeaderScrollingViewBehavior.java:90)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5933)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:775)
at android.view.Choreographer.doCallbacks(Choreographer.java:588)
at android.view.Choreographer.doFrame(Choreographer.java:558)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:761)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5276)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:911)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:706)

我的java文件如下 -

    package com.gjs.mapandpaypa;
    import android.content.pm.PackageManager;
    import android.os.Bundle;
    import android.support.v4.app.ActivityCompat;
    import android.support.v4.app.Fragment;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;

    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;

    public class BlankFragment extends Fragment implements OnMapReadyCallback {
        GoogleMap mMap=null;
        SupportMapFragment mapFragment=null;

    public BlankFragment() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View view= inflater.inflate(R.layout.fragment_blank, container, false);
        mapFragment = ((SupportMapFragment) getChildFragmentManager()
                       .findFragmentById(R.id.map));
            mapFragment.getMapAsync(this);
        return view;

    }
    @Override
    public void onDestroy() {
        super.onDestroy();
        if (mapFragment != null) {
            mapFragment = null;
        }
    }

    @Override
    public void onMapReady(GoogleMap googleMap) {
        mMap = googleMap;
        //Toast.makeText(getActivity(), lat + "   " + lng, Toast.LENGTH_LONG).show();

        LatLng locations = new LatLng(0,0);

        if (ActivityCompat.checkSelfPermission(getActivity(), android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(getActivity(), android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            // TODO: Consider calling
            //    ActivityCompat#requestPermissions
            // here to request the missing permissions, and then overriding
            //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
            //                                          int[] grantResults)
            // to handle the case where the user grants the permission. See the documentation
            // for ActivityCompat#requestPermissions for more details.
            return;
        }
        mMap.setMyLocationEnabled(true);
        mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(locations, 13));

        mMap.addMarker(new MarkerOptions()
                .title("abc")

                .position(locations));
    }
    @Override
    public void onPause() {
        super.onPause();

        getChildFragmentManager().beginTransaction()
                .remove(mapFragment)
                .commit();
    }
}

我的xml文件在下面给出 -

     <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.gjs.mapandpaypa.BlankFragment">

    <!-- TODO: Update blank fragment layout -->
    <fragment xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="350dp"
        android:layout_height="200dp"
        android:layout_marginTop="20dp"
        android:id="@+id/map"
        android:layout_below="@+id/textView6"
        android:layout_alignParentLeft="true"
        android:name="com.google.android.gms.maps.SupportMapFragment"
        android:layout_alignParentStart="true"
        android:layout_marginLeft="19dp"
        android:layout_marginStart="19dp" />

</FrameLayout>

尝试调用虚方法＆＃39; java.lang.Class java.lang.Object.getClass（）

0 个答案: