爲什麼這個地圖程序「意外停止」？

我試圖從Android開發者HelloGoogleMaps教程結合locationlistener和locationmanager編輯google地圖，這樣overlay項目將被放置在我當前位置的地理點（經度，緯度）。我是一個在Android的極端初學者，所以請用簡單的語言來幫助我！的xD爲什麼這個地圖程序「意外停止」？

我SampleMap.java文件：

package com.example.samplemap; 

     import java.util.List; 

import android.content.Context; 
import android.graphics.drawable.Drawable; 
import android.location.Location; 
import android.location.LocationListener; 
import android.location.LocationManager; 
import android.os.Bundle; 
import android.util.Log; 
import android.widget.Toast; 

import com.google.android.maps.GeoPoint; 
import com.google.android.maps.MapActivity; 
import com.google.android.maps.MapView; 
import com.google.android.maps.Overlay; 
import com.google.android.maps.OverlayItem; 


     public class SampleMap extends MapActivity { 
     /** Called when the activity is first created. */ 
     Location location; 
     @Override 
     protected boolean isRouteDisplayed() { 
     return false; 
     } 

     double lat = location.getLatitude(); 
     double lng = location.getLongitude(); 

     @Override 
     public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.main); 

     LocationManager lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE); 
     LocationListener ll = new mylocationlistener(); 
     lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, ll); 

     MapView mapView = (MapView) findViewById(R.id.mapview); 
     mapView.setBuiltInZoomControls(true); 

     List<Overlay> mapOverlays = mapView.getOverlays(); 
     Drawable drawable = this.getResources().getDrawable(R.drawable.androidmarker); 

     HelloItemizedOverlay itemizedoverlay = new HelloItemizedOverlay(drawable); 
     GeoPoint point = new GeoPoint((int) (lat), (int) (lng)); 
     OverlayItem overlayitem = new OverlayItem(point, "", ""); 

     itemizedoverlay.addOverlay(overlayitem); 
     mapOverlays.add(itemizedoverlay); 

     } 

     private class mylocationlistener implements LocationListener { 
      @Override 
      public void onLocationChanged(Location location) { 
       if (location != null) { 
       Log.d("LOCATION CHANGED", location.getLatitude() + ""); 
       Log.d("LOCATION CHANGED", location.getLongitude() + ""); 
       Toast.makeText(SampleMap.this, 
        location.getLatitude() + " " + location.getLongitude(), 
        Toast.LENGTH_LONG).show(); 
       } 
      } 
      @Override 
      public void onProviderDisabled(String provider) { 
      } 
      @Override 
      public void onProviderEnabled(String provider) { 
      } 
      @Override 
      public void onStatusChanged(String provider, int status, Bundle extras) { 
      } 

      } 

     }

和我HelloItemizedOverly.java

package com.example.samplemap; 

import java.util.ArrayList; 

import android.app.AlertDialog; 
import android.content.Context; 
import android.graphics.drawable.Drawable; 

import com.google.android.maps.ItemizedOverlay; 
import com.google.android.maps.OverlayItem; 


public class HelloItemizedOverlay extends ItemizedOverlay<OverlayItem> { 
private ArrayList<OverlayItem> mOverlays = new ArrayList<OverlayItem>(); 
Context mContext; 
public HelloItemizedOverlay(Drawable defaultMarker) { 
super(boundCenterBottom(defaultMarker)); 
// TODO Auto-generated constructor stub 
} 
public HelloItemizedOverlay(Drawable defaultMarker, Context context) { 
super(defaultMarker); 
mContext = context; 
} 
public void addOverlay(OverlayItem overlay) { 
mOverlays.add(overlay); 
populate(); 
} 
@Override 
protected OverlayItem createItem(int i) { 
return mOverlays.get(i); 
} 
@Override 
public int size() { 
return mOverlays.size(); 
} 
@Override 
protected boolean onTap(int index) { 
OverlayItem item = mOverlays.get(index); 
Context mContext = null; 
AlertDialog.Builder dialog = new AlertDialog.Builder(mContext); 
dialog.setTitle(item.getTitle()); 
dialog.setMessage(item.getSnippet()); 
dialog.show(); 
return true; 
} 
}

和清單：

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
package="com.example.samplemap" 
     android:versionCode="1" 
     android:versionName="1.0"> 
     <uses-sdk android:minSdkVersion="8" /> 
     <uses-permission android:name="android.permission.INTERNET" /> 
     <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"> </uses- permission> 
     <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"></uses-permission> 
     <uses-permission android:name="android.permission.INTERNET" /> 
     <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" /> 
     <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" /> 
     <uses-permission android:name="android.permission.ACCESS_LOCATION_EXTRA_COMMANDS" /> 
     <uses-permission android:name="android.permission.ACCESS_MOCK_LOCATION" /> 
     <uses-permission android:name="android.permission.CONTROL_LOCATION_UPDATES" /> 

     <application android:icon="@drawable/icon" android:label="@string/app_name"> 
     <uses-library android:name="com.google.android.maps" /> 

     <activity android:name=".SampleMap" 
     android:label="@string/app_name" 
     android:theme="@android:style/Theme.NoTitleBar"> 
     <intent-filter> 
     <action android:name="android.intent.action.MAIN" /> 
     <category android:name="android.intent.category.LAUNCHER" /> 
     </intent-filter> 
     </activity> 

     </application> 
     </manifest>

你能不能也給我許可的代碼，我需要??? >。 <

DDMS log cat: 
07-26 13:53:27.077: DEBUG/EAS SyncManager(2258): !!! EAS SyncManager, onCreate 
07-26 13:53:27.171: DEBUG/Eas Debug(2258): Logging: 
07-26 13:53:27.179: DEBUG/EAS SyncManager(2258): !!! EAS SyncManager, onDestroy 
07-26 13:53:28.296: DEBUG/dalvikvm(2258): GC_FOR_MALLOC freed 3927 objects/265008 bytes in 44ms 
07-26 13:53:28.890: DEBUG/dalvikvm(1699): GC_EXPLICIT freed 265 objects/15568 bytes in 86ms 
07-26 13:53:29.429: DEBUG/Email(2258): *** synchronizeMailboxGeneric *** 
07-26 13:53:30.398: INFO/ActivityManager(1103): No longer want com.google.android.apps.uploader (pid 2084): hidden #16 
07-26 13:53:30.421: INFO/UsageStats(1103): Something wrong here, didn't expect com.example.samplemap to be paused 
07-26 13:53:30.925: WARN/ActivityManager(1103): Activity pause timeout for HistoryRecord{44a2a790 com.example.samplemap/.SampleMap} 
07-26 13:53:33.882: DEBUG/dalvikvm(1187): GC_EXPLICIT freed 1914 objects/112528 bytes in 75ms 
07-26 13:53:38.874: DEBUG/dalvikvm(2011): GC_EXPLICIT freed 91 objects/8040 bytes in 69ms 
07-26 13:53:40.426: WARN/ActivityManager(1103): Activity idle timeout for HistoryRecord{44a2a790 com.example.samplemap/.SampleMap} 
07-26 13:53:45.499: DEBUG/dalvikvm(2019): GC_EXPLICIT freed 304 objects/17824 bytes in 76ms 
07-26 13:53:50.491: DEBUG/dalvikvm(2074): GC_EXPLICIT freed 135 objects/6720 bytes in 66ms 
07-26 13:53:55.507: DEBUG/dalvikvm(1560): GC_EXPLICIT freed 65 objects/3896 bytes in 75ms 
07-26 13:54:05.132: DEBUG/dalvikvm(1726): GC_EXPLICIT freed 46 objects/2216 bytes in 54ms 
07-26 13:54:10.171: DEBUG/dalvikvm(1445): GC_EXPLICIT freed 268 objects/9960 bytes in 94ms 
07-26 13:54:15.156: DEBUG/dalvikvm(1215): GC_EXPLICIT freed 1011 objects/51888 bytes in 75ms 
07-26 13:54:16.804: DEBUG/KeyguardViewMediator(1103): wakeWhenReadyLocked(26) 
07-26 13:54:16.804: DEBUG/KeyguardViewMediator(1103): handleWakeWhenReady(26) 
07-26 13:54:16.804: DEBUG/KeyguardViewMediator(1103): pokeWakelock(5000) 
07-26 13:54:16.804: INFO/power(1103): *** set_screen_state 1 
07-26 13:54:16.829: DEBUG/Sensors(1103): using sensors (name=sensors) 
07-26 13:54:16.851: INFO/UsageStats(1103): Unexpected resume of com.example.samplemap while already resumed in com.example.samplemap 
07-26 13:54:16.882: DEBUG/WifiService(1103): ACTION_SCREEN_ON 
07-26 13:54:17.124: DEBUG/dalvikvm(1184): GC_FOR_MALLOC freed 11174 objects/598888 bytes in 105ms 
07-26 13:54:17.382: DEBUG/SurfaceFlinger(1103): Screen about to return, flinger = 0x120f38 
07-26 13:54:19.085: DEBUG/WindowManager(1103): I'm tired mEndcallBehavior=0x2 
07-26 13:54:19.328: INFO/power(1103): *** set_screen_state 0 
07-26 13:54:19.341: DEBUG/SurfaceFlinger(1103): About to give-up screen, flinger = 0x120f38 
07-26 13:54:19.359: DEBUG/Sensors(1103): using accelerometer (name=accelerometer) 
07-26 13:54:19.374: DEBUG/WifiService(1103): ACTION_SCREEN_OFF 
07-26 13:54:19.382: DEBUG/WifiService(1103): setting ACTION_DEVICE_IDLE timer for 900000ms 
07-26 13:54:19.870: WARN/ActivityManager(1103): Activity pause timeout for HistoryRecord{44a2a790 com.example.samplemap/.SampleMap}

來源

2011-07-26 Eric

你在Eclipse這樣做？你能從DDMS的角度發佈Logcat的輸出嗎？ – Estel

哈哈，我不知道我應該使用哪個時間段... – Eric

在你的logcat上，你可以按下「E」按鈕來只獲得錯誤，這通常是有幫助的，控制檯也可以顯示堆棧跟蹤打印輸出，這假定你正在使用eclipse – Idistic

好一兩件事，它看起來像你想它初始化之前訪問該位置的變量，因爲你經度/緯度和位置瓦爾是此類範圍內的位置實際上是初始化之前他們將得到初始化（如果它曾經是）

double lat = location.getLatitude(); // location is never set, it will be null! 
double lng = location.getLongitude();

由於事實上我甚至不看你初始化位置（你有你的更新同名的參數變量，但我看不出你是移動的類別範圍版本）

public void onLocationChanged(Location location) {/

即使你不喜歡的東西

this.location = new Location(location);

裏面的聽衆，你不知道什麼時候這將創建（或即使）

而且MyLocationOverlay是一個內置的疊加谷歌地圖是將爲您處理所有這些。

更新跌落的位置VAR頂部

變化附近

double lat = location.getLatitude(); 
double lng = location.getLongitude();

到

double lat = 0; 
double lng = 0;

然後裏面你的位置監聽器掉落雙倍，你只是在創建本地如果你這樣做。

lat = location.getLatitude(); 
lng = location.getLongitude();

至少會照顧這個問題的，我再次看到的鏈接MyLocationOverlay，它需要照顧的一切對你的問候當前位置

來源

2011-07-26 18:02:51 Idistic

你是什麼意思的類作用域？ – Eric

我的意思是這個位置的位置;在類的頂部，並且可用於任何方法，與此public void onLocationChanged（Location location）不同（僅在位置偵聽器中可用）。您嘗試使用該類的範圍之前，它實際上initalized - 我更新了上面的答案 – Idistic

public void onLocationChanged（Location location）{ double lat = location.getLatitude（）; double lng = location.getLongitude（）; } – Eric

爲什麼這個地圖程序「意外停止」？

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