为什么我在我的吸气剂上得到一个空指针
[英]Why I am getting a null pointer at my getter
问题描述
Please give me a clue why I am getting a null pointer where I am getting the value of getlatitude and how I can fix it?? 
请给我一个线索，为什么我在获取getlatitude的值时会得到一个空指针以及如何解决它？
Main Activity 主要活动
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
p = new Proximity();
NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
initLocationFetching(MainActivity.this);
}
@Override
public void locationFetched(Location mLocal, Location oldLocation, String time, String locationProvider) {
super.locationFetched(mLocal, oldLocation, time, locationProvider);
p.setLatitude(mLocal.getLatitude());
p.setLongitude(mLocal.getLongitude());
}
On My fragment where I am getting the value 在我获得价值的片段上
Proximity p = new Proximity();
public MapFragment(Context c, Activity a) { context = c; activity = a;}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View v = inflater.inflate(R.layout.fragment_contact_us, container, false);
if (android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
checkLocationPermission();
}
// Initializing
MarkerPoints = new ArrayList<>();
Toast.makeText(context, "Asdasdasdasdas"+p.getLatitude().toString(), Toast.LENGTH_SHORT).show();
Proximity 接近
public class Proximity {
Double latitude;
public Double getLatitude() {
return latitude;
}
public void setLatitude(Double latitude) {
this.latitude = latitude;
}
public Double getLongitude() {
return longitude;
}
public void setLongitude(Double longitude) {
this.longitude = longitude;
}
Double longitude;
}
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.mark/com.mark.activity.MainActivity}: java.lang.NullPointerException at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245) at android.app.ActivityThread.access$800(ActivityThread.java:135) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:136) at android.app.ActivityThread.main(ActivityThread.java:5021) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:515) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:827) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:643) at dalvik.system.NativeStart.main(Native Method) Caused by: java.lang.NullPointerException at com.fragment.MapFragment.onCreateView(MapFragment.java:113
1 个解决方案
解决方案1
2 已采纳 2017-07-24 04:15:16
In your fragment you have created an object p Proximity p = new Proximity(); 在您的片段中，您创建了一个对象p Proximity p = new Proximity(); But the member variable latitude (Assuming that it is an object) is not set. 但是未设置成员变量latitude （假设它是一个对象）。 ie latitude is null. 即纬度为空。 As per the logs, in MapFragment.java: line no. 113 根据日志，在MapFragment.java: line no. 113 MapFragment.java: line no. 113 you are trying to access it. MapFragment.java: line no. 113您正在尝试访问它。 I think it is the code to show Toast where p.getLatitude().toString() results in NullPointerException. 我认为这是显示Toast的代码，其中p.getLatitude().toString()导致NullPointerException。
You may have to pass Proximity instance to fragment either using Fragment.setArguments while adding the fragment or create a method in your fragment and access it from activity. 您可能需要在添加Fragment.setArguments时使用Fragment.setArguments将Proximity实例传递给片段，或者在片段中创建方法并从活动中访问它。 As the code for Proximity is not a posted I assume that lat and long are Objects not primitive data types. 由于没有发布用于Proximity的代码，因此我假设lat和long都不是原始数据类型的对象。
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