我正在尝试使用路径显示当前位置的地图。跑步时崩溃了。
我也检查了清单..但我不知道错误是什么..
PLease帮助我，我是android中的新蜜蜂..
这是我的代码：
MapActivity.java
package com.GoogleMaps;
import java.util.List;
import com.google.android.maps.GeoPoint;
import com.google.android.maps.MapActivity;
import com.google.android.maps.MapController;
import com.google.android.maps.MapView;
import com.google.android.maps.Overlay;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Point;
import android.graphics.drawable.Drawable;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.widget.Toast;
public class MapsActivity extends MapActivity {
/** Called when the activity is first created. */
private MapView mapView;
private LocationManager lm;
private LocationListener ll;
private MapController mc;
GeoPoint p = null;
Drawable defaultMarker = null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mapView = (MapView)findViewById(R.id.mapview);
//show zoom in/out buttons
mapView.setBuiltInZoomControls(true);
//Standard view of the map(map/sat)
mapView.setSatellite(false);
//get controller of the map for zooming in/out
mc = mapView.getController();
// Zoom Level
mc.setZoom(18);
// MyLocationOverlay myLocationOverlay = new MyLocationOverlay();
List<Overlay> list = mapView.getOverlays();
// list.add(myLocationOverlay);
lm = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
ll = new MyLocationListener();
lm.requestLocationUpdates(
LocationManager.GPS_PROVIDER,
0,
0,
ll);
//Get the current location in start-up
GeoPoint initGeoPoint = new GeoPoint(
(int)(lm.getLastKnownLocation(LocationManager.GPS_PROVIDER).getLatitude()*1000000),
(int)(lm.getLastKnownLocation(LocationManager.GPS_PROVIDER).getLongitude()*1000000));
mc.animateTo(initGeoPoint);
}
protected class MyLocationOverlay extends com.google.android.maps.Overlay {
@Override
public boolean draw(Canvas canvas, MapView mapView, boolean shadow, long when) {
Paint paint = new Paint();
super.draw(canvas, mapView, shadow);
// Converts lat/lng-Point to OUR coordinates on the screen.
Point myScreenCoords = new Point();
mapView.getProjection().toPixels(p, myScreenCoords);
paint.setStrokeWidth(1);
paint.setARGB(255, 255, 255, 255);
paint.setStyle(Paint.Style.STROKE);
Bitmap bmp = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);
canvas.drawBitmap(bmp, myScreenCoords.x, myScreenCoords.y, paint);
canvas.drawText("I am here...", myScreenCoords.x, myScreenCoords.y, paint);
return true;
}
}
private class MyLocationListener implements LocationListener{
public void onLocationChanged(Location argLocation) {
// TODO Auto-generated method stub
GeoPoint myGeoPoint = new GeoPoint((int)(argLocation.getLatitude()*1000000), (int)(argLocation.getLongitude()*1000000));
Toast.makeText(getBaseContext(),
"New location latitude [" +argLocation.getLatitude() +
"] longitude [" + argLocation.getLongitude()+"]",
Toast.LENGTH_SHORT).show();
mc.animateTo(myGeoPoint);
}
public void onProviderDisabled(String provider) {
// TODO Auto-generated method stub
}
public void onProviderEnabled(String provider) {
// TODO Auto-generated method stub
}
public void onStatusChanged(String provider,
int status, Bundle extras) {
// TODO Auto-generated method stub
}
}
protected boolean isRouteDisplayed() {
return false;
}
}
main.xml中：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<LinearLayout
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
>
<TextView
android:id="@+id/longitude"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:text="Longitude:"
/>
<TextView
android:id="@+id/latitude"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:text="Latitude:"
/>
</LinearLayout>
<com.google.android.maps.MapView
android:id="@+id/mapview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:clickable="false"
android:apiKey="0dB02TjP-H_UqgsDpfxAhtsvGo5Z8cUJsTeHeDA"
/>
</LinearLayout>
清单文件：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.GoogleMaps"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk android:minSdkVersion="8" />
<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name" >
<uses-library android:required="true" android:name="com.google.android.maps"/>
<activity
android:label="@string/app_name"
android:name=".MapsActivity" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<uses-library android:name="com.google.android.maps" />
</application>
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-sdk android:minSdkVersion="8" />
</manifest>
logcat文件：
11-29 03:26:49.620: D/AndroidRuntime(671): Shutting down VM
11-29 03:26:49.620: W/dalvikvm(671): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
11-29 03:26:49.640: E/AndroidRuntime(671): FATAL EXCEPTION: main
11-29 03:26:49.640: E/AndroidRuntime(671): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.GoogleMaps/com.GoogleMaps.MapsActivity}: java.lang.NullPointerException
11-29 03:26:49.640: E/AndroidRuntime(671): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
11-29 03:26:49.640: E/AndroidRuntime(671): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
11-29 03:26:49.640: E/AndroidRuntime(671): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
11-29 03:26:49.640: E/AndroidRuntime(671): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
11-29 03:26:49.640: E/AndroidRuntime(671): at android.os.Handler.dispatchMessage(Handler.java:99)
11-29 03:26:49.640: E/AndroidRuntime(671): at android.os.Looper.loop(Looper.java:123)
11-29 03:26:49.640: E/AndroidRuntime(671): at android.app.ActivityThread.main(ActivityThread.java:4627)
11-29 03:26:49.640: E/AndroidRuntime(671): at java.lang.reflect.Method.invokeNative(Native Method)
11-29 03:26:49.640: E/AndroidRuntime(671): at java.lang.reflect.Method.invoke(Method.java:521)
11-29 03:26:49.640: E/AndroidRuntime(671): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
11-29 03:26:49.640: E/AndroidRuntime(671): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
11-29 03:26:49.640: E/AndroidRuntime(671): at dalvik.system.NativeStart.main(Native Method)
11-29 03:26:49.640: E/AndroidRuntime(671): Caused by: java.lang.NullPointerException
11-29 03:26:49.640: E/AndroidRuntime(671): at com.GoogleMaps.MapsActivity.onCreate(MapsActivity.java:65)
11-29 03:26:49.640: E/AndroidRuntime(671): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
11-29 03:26:49.640: E/AndroidRuntime(671): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
11-29 03:26:49.640: E/AndroidRuntime(671): ... 11 more
11-29 03:26:52.320: I/Process(671): Sending signal. PID: 671 SIG: 9
答案 0 :(得分：1)
您在MapsActivity类的第65行获得NullPointerException。你可以自己发布这条线吗？
可能的罪魁祸首是你不检查getLastLocation是否返回null，这是可能的。
使用空检查包围这些行
//Get the current location in start-up, if it exists
if (lm.getLastKnownLocation(LocationManager.GPS_PROVIDER) != null) {
GeoPoint initGeoPoint = new GeoPoint(
(int)(lm.getLastKnownLocation(LocationManager.GPS_PROVIDER).getLatitude()*1000000),
(int)(lm.getLastKnownLocation(LocationManager.GPS_PROVIDER).getLongitude()*1000000));
mc.animateTo(initGeoPoint);
}