[英]NullPointerException - Working with Location in Fragments
尝试运行应用程序时,我意外收到了以下NullPointer Exception错误。
09-22 20:22:49.981: E/AndroidRuntime(4751): FATAL EXCEPTION: main
09-22 20:22:49.981: E/AndroidRuntime(4751): Process: com.dooba.beta, PID: 4751
09-22 20:22:49.981: E/AndroidRuntime(4751): java.lang.NullPointerException
09-22 20:22:49.981: E/AndroidRuntime(4751): at com.dooba.beta.Fragment1.setConversationsList(Fragment1.java:154)
09-22 20:22:49.981: E/AndroidRuntime(4751): at com.dooba.beta.Fragment1.onActivityCreated(Fragment1.java:97)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.support.v4.app.Fragment.performActivityCreated(Fragment.java:1468)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:931)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1088)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1444)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:461)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.support.v4.view.ViewPager.populate(ViewPager.java:1011)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.support.v4.view.ViewPager.populate(ViewPager.java:880)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1374)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.view.View.measure(View.java:16497)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.view.View.measure(View.java:16497)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.view.View.measure(View.java:16497)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
09-22 20:22:49.981: E/AndroidRuntime(4751): at com.android.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:327)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.view.View.measure(View.java:16497)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
09-22 20:22:49.981: E/AndroidRuntime(4751): at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2291)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.view.View.measure(View.java:16497)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1916)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1113)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1295)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1000)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5670)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.view.Choreographer.doCallbacks(Choreographer.java:574)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.view.Choreographer.doFrame(Choreographer.java:544)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:747)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.os.Handler.handleCallback(Handler.java:733)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.os.Handler.dispatchMessage(Handler.java:95)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.os.Looper.loop(Looper.java:136)
09-22 20:22:49.981: E/AndroidRuntime(4751): at android.app.ActivityThread.main(ActivityThread.java:5017)
09-22 20:22:49.981: E/AndroidRuntime(4751): at java.lang.reflect.Method.invokeNative(Native Method)
09-22 20:22:49.981: E/AndroidRuntime(4751): at java.lang.reflect.Method.invoke(Method.java:515)
09-22 20:22:49.981: E/AndroidRuntime(4751): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
09-22 20:22:49.981: E/AndroidRuntime(4751): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
09-22 20:22:49.981: E/AndroidRuntime(4751): at dalvik.system.NativeStart.main(Native Method)
以下是第154行所指示的内容,我假设第155行应出现类似的问题。
Location ln;
Location lt;
double longi=lt.getLongitude();
double lati=ln.getLatitude();
ParseGeoPoint point = new ParseGeoPoint(lati, longi);
query.whereWithinKilometers("location", point, 100);
本质上,我试图根据各种条件来检索用户,在这种情况下,它是引起问题的位置。
任何帮助将不胜感激。 提前致谢。
更新:
Location location = new Location(""); // location
double lati; // latitude
double longi; // longitude
lati = location.getLatitude();
longi = location.getLongitude();
ParseGeoPoint point = new ParseGeoPoint(lati, longi);
query.whereWithinKilometers("location", point, 100);
更新2:
我设法使用以下方法来获取用户的纬度和经度:
@Override
public void onLocationChanged(Location userLocation) {
// TODO Auto-generated method stub
double lati = userLocation.getLatitude();
double longi = userLocation.getLongitude();
}
问题是将其合并到当前的片段代码中是有问题的。
private void setConversationsList() {
currentUserId = ParseUser.getCurrentUser().getObjectId();
// String userActivitySelectionName = null;
ParseQuery<ParseUser> query = ParseUser.getQuery();
// query.whereEqualTo("ActivityName",userActivitySelectionName);
query.whereNotEqualTo("objectId", ParseUser.getCurrentUser()
.getObjectId());
query.setLimit(1);
Location location = new Location(""); // location
double lati; // latitude
double longi; // longitude
lati = location.getLatitude();
longi = location.getLongitude();
ParseGeoPoint point = new ParseGeoPoint(57, -122);
query.whereWithinKilometers("location", point, 1113);
query.orderByDescending("Name");
ParseQuery<ParseUser> query1 = ParseUser.getQuery();
在ctrl-fing代码之后,我没有找到lt的任何赋值('lt =','lt'或'(lt)')。 您可能应该在使用变量之前对其进行初始化。 另外,您应该削减不相关的代码部分,这样人们就不必阅读大约200-300行与您的问题无关的代码。
您似乎缺乏字段/变量初始化的基本知识,但是无论如何,我最近做了类似的事情,您可以在此处查看代码: https : //github.com/dbarwacz/Beton
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