java.lang.NullPointerException :com. 谷歌.android.gms.maps.GoogleMap.moveCamera

Question

我目前正在研究新的 Google Maps Android API v2。

我的 MapActivity 类使用下面的代码与我的三星 galaxy s3 ans s2 一起工作:

但是，有一些特定的设备不​​工作，例如:GT-S5830i

class MapActivity extends FragmentActivity  implements OnMapClickListener, OnMapLongClickListener, OnMarkerClickListener
{

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_map);

                tvLocInfo = (TextView)findViewById(R.id.locinfo);

                android.support.v4.app.FragmentManager myFragmentManager = getSupportFragmentManager();
                SupportMapFragment myMapFragment = (SupportMapFragment)myFragmentManager.findFragmentById(R.id.map);
                myMap = myMapFragment.getMap();

                myMap.setMapType(GoogleMap.MAP_TYPE_HYBRID);
                ArrayList<Cooridnates> cooridnatesList = MainActivity.getList();
                for(int i=0;i<cooridnatesList.size();i++)
                {
                    //Toast.makeText(MapActivity.this, "SIZE : " + " " + cooridnatesList.size(), Toast.LENGTH_LONG).show();
                    LatLng point = new LatLng(cooridnatesList.get(i).getLat(),cooridnatesList.get(i).getLon());
                    tvLocInfo.setText("markers added");
                    myMap.addMarker(new MarkerOptions().position(point).title(point.toString()));
                    center=CameraUpdateFactory.newLatLng(point);
                }

                CameraUpdate zoom=CameraUpdateFactory.zoomTo(16);
                myMap.moveCamera(center);
                myMap.animateCamera(zoom);
                myMap.setOnMapClickListener(this);
                myMap.setOnMarkerClickListener(this);
                markerClicked = false;
             }

出于某种原因，我收到此错误:

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.coldice.plotfinder/com.coldice.plotfinder.MapActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1651)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1667)
at android.app.ActivityThread.access$1500(ActivityThread.java:117)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:935)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:130)
at android.app.ActivityThread.main(ActivityThread.java:3687)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:507)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.google.android.gms.maps.GoogleMap.moveCamera(Unknown Source)
at com.coldice.plotfinder.MapActivity.onCreate(MapActivity.java:70)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1615)
... 11 more

Answer 1

您的函数 MainActivity.getList() 可能返回了一个空列表，因此 for 循环不会执行 center=CameraUpdateFactory.newLatLng(point);。