有人可以帮我解决这个Android位置错误吗？
[英]Can someone help me please with this android location error?
问题描述
Hello I m new to programming and the android platform and I m developing an app using the Google Maps Api v2 and location services using Android Studio 1.02.Basically when someone launches the app, it will instantly zoom on it s users current location and i m encountering some weird problems on this.And By weird I mean it worked after I rad it on my device multiple times but after 2 days ( while i was out f town) I ran it again the app crashed on launch and this error apeared: 
您好，我m new to programming and the android platform and I使用Google Maps Api v2开发了一个应用程序，并使用Android Studio 1.02开发了位置服务。基本上，当有人启动该应用程序时，它会立即放大其s users current location and i遇到一些奇怪的问题。怪异的是，它是在我多次将其放在我的设备上销售后才起作用的，但是两天后（当我不在城镇时），我再次运行它，该应用在启动时崩溃了，此错误消失了：
Is there a way to fix this ? 有没有办法解决这个问题 ？
Also how do you manage to put a actionBar in android studio 1.02 because I can`t figure a way to do it. 另外，您如何将actionBar放入android studio 1.02中，因为我找不到解决方法。
The Logcat: Logcat：
02-07 14:15:12.350 21921-21921/com.nanocat.viapp E/AndroidRuntime﹕ FATAL EXCEPTION: main Process: com.nanocat.viapp, PID: 21921 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.nanocat.viapp/com.nanocat.viapp.MapsActivity}: java.lang.NullPointerException at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2305) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2363) at android.app.ActivityThread.access$900(ActivityThread.java:161) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1265) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:157) at android.app.ActivityThread.main(ActivityThread.java:5356) 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:1265) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081) at dalvik.s
My MapsActivity class: 我的MapsActivity类：
package com.nanocat.viapp;
import android.content.Context;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationManager;
import android.support.v4.app.FragmentActivity;
import android.os.Bundle;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.CameraPosition;
import com.google.android.gms.maps.model.LatLng;
public class MapsActivity extends FragmentActivity {
private GoogleMap mMap;
double latitude;
double longitude;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_maps);
setUpMapIfNeeded();
}
@Override
protected void onResume() {
super.onResume();
setUpMapIfNeeded();
}
private void setUpMapIfNeeded() {
if (mMap == null) {
mMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map))
.getMap();
if (mMap != null) {
setUpMap();
}
}
}
public void setUpMap() {
Criteria criteria = new Criteria();
LocationManager locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
String provider = locationManager.getBestProvider(criteria, true);
Location myLocation = locationManager.getLastKnownLocation(provider);
latitude = myLocation.getLatitude();
longitude = myLocation.getLongitude();
LatLng latLng = new LatLng(latitude, longitude);
mMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));
CameraPosition cameraPosition = new CameraPosition.Builder()
.target(latLng)
.tilt(60)
.zoom(17)
.build();
mMap.animateCamera(CameraUpdateFactory.newCameraPosition(cameraPosition));
}
}
My Manifest.xml : 我的Manifest.xml：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.nanocat.viapp" >
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<meta-data
android:name="com.google.android.gms.version"
android:value="@integer/google_play_services_version" />
<meta-data
android:name="com.google.android.maps.v2.API_KEY"
android:value="@string/google_maps_key" />
<activity
android:name=".MapsActivity"
android:label="@string/title_activity_maps" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
And my Layout : 和我的布局：
<fragment
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"
android:id="@+id/map"
tools:context=".MapsActivity"
android:name="com.google.android.gms.maps.SupportMapFragment" />
1 个解决方案
解决方案1
0 2015-02-07 13:03:51
The problem is due of 问题是由于
Location myLocation = locationManager.getLastKnownLocation(provider);
getLastKnowLocation returns null if a location has not been yet acquired. 如果尚未获取位置，则getLastKnowLocation返回null。 So you should at least check against null Location objects 因此，您至少应检查空的Location对象
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