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我開發了一個簡單的mapActivity，也就是說用戶通過使用對話框警報和定位服務的意圖來檢查他是否啓用了GPS系統。如果GPS啓用它直接到地圖查看，但這不會發生在我身上。當我按下去mapView時，它會讓我強制關閉。錯誤的地圖活動
這是對話框代碼：
public void onClick(View arg0) {
AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(
context);
// set title
alertDialogBuilder.setTitle("Your Title");
// set dialog message
alertDialogBuilder
.setMessage("Click yes TO ENABLE GPS")
.setCancelable(false)
.setPositiveButton("Yes",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,
int id) {
// if this button is clicked, close
// current activity
Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
startActivityForResult(intent, 1);
}
})
.setNegativeButton("No",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,
int id) {
// if this button is clicked, just close
// the dialog box and do nothing
//dialog.cancel();
Intent intent = new Intent(MainActivity.this, AndroidGoogleMapsActivity.class);
context.startActivity(intent);
}
});
// create alert dialog
AlertDialog alertDialog = alertDialogBuilder.create();
// show it
alertDialog.show();
}
});
}
這是清單文件：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.mkyong.android"
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"/>
<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name" >
<uses-library
android:name="com.google.android.maps"
android:required="true" />
<activity
android:name=".MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".AndroidGoogleMapsActivity" >
</activity>
</application>
</manifest>
這是AndroidGoogleMapsActivity類
公共類AndroidGoogleMapsActivity擴展MapActivity {
的代碼@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// Displaying Zooming controls
MapView mapView = (MapView) findViewById(R.id.mapView);
Log.d("error", "the negative button befor the line 27 ");
mapView.setBuiltInZoomControls(true);
Log.d("error", "the negative button after the line 27 befor the map view settings ");
mapView.setSatellite(true); // Satellite View
Log.d("error", "the negative button after the line 27 after satellite view ");
mapView.setStreetView(false); // Street View
Log.d("error", "the negative button after the line 27 after street view ");
mapView.setTraffic(true); // Traffic view
Log.d("error", "the negative button after the line 27 after the map view settings ");
MapController mc = mapView.getController();
Log.d("error", "the negative button after the line 27 after the mapController ");
double lat = Double.parseDouble("33.823862");// kehale
double lon = Double.parseDouble("35.590248");// kehale
GeoPoint geoPoint = new GeoPoint((int)(lat * 1E6), (int)(lon * 1E6));
mc.animateTo(geoPoint);
mc.setZoom(15);
mapView.invalidate();
Log.d("error", "the negative button befor the GeoPoint");
@Override
protected boolean isRouteDisplayed() {
return false;
}
}
這是我得到的錯誤：
09-20 05:16:22.512: D/AndroidRuntime(309): Shutting down VM
09-20 05:16:22.512: W/dalvikvm(309): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
09-20 05:16:22.543: E/AndroidRuntime(309): FATAL EXCEPTION: main
09-20 05:16:22.543: E/AndroidRuntime(309): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.mkyong.android/com.mkyong.android.AndroidGoogleMapsActivity}: java.lang.NullPointerException
09-20 05:16:22.543: E/AndroidRuntime(309): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
09-20 05:16:22.543: E/AndroidRuntime(309): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
09-20 05:16:22.543: E/AndroidRuntime(309): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
09-20 05:16:22.543: E/AndroidRuntime(309): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
09-20 05:16:22.543: E/AndroidRuntime(309): at android.os.Handler.dispatchMessage(Handler.java:99)
09-20 05:16:22.543: E/AndroidRuntime(309): at android.os.Looper.loop(Looper.java:123)
09-20 05:16:22.543: E/AndroidRuntime(309): at android.app.ActivityThread.main(ActivityThread.java:4627)
09-20 05:16:22.543: E/AndroidRuntime(309): at java.lang.reflect.Method.invokeNative(Native Method)
09-20 05:16:22.543: E/AndroidRuntime(309): at java.lang.reflect.Method.invoke(Method.java:521)
09-20 05:16:22.543: E/AndroidRuntime(309): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
09-20 05:16:22.543: E/AndroidRuntime(309): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
09-20 05:16:22.543: E/AndroidRuntime(309): at dalvik.system.NativeStart.main(Native Method)
09-20 05:16:22.543: E/AndroidRuntime(309): Caused by: java.lang.NullPointerException
09-20 05:16:22.543: E/AndroidRuntime(309): at com.mkyong.android.AndroidGoogleMapsActivity.onCreate(AndroidGoogleMapsActivity.java:27)
09-20 05:16:22.543: E/AndroidRuntime(309): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
09-20 05:16:22.543: E/AndroidRuntime(309): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
09-20 05:16:22.543: E/AndroidRuntime(309): ... 11 more
09-20 05:16:25.141: I/Process(309): Sending signal. PID: 309 SIG: 9
對不起你們，我新來這個論壇感謝您的幫助 – jiji
的問題是在你的AndroidGoogleMapsActivity .onCreate（）方法，如果可能，請張貼方法的代碼以及行號，或者告訴我們什麼行是第27行，因爲這是拋出NullPointerException的地方 –
好吧我編輯我的問題與類，我知道錯誤是在27行，但我不知道如何解決它，謝謝你 – jiji