我为什么要这样做？应用程序运行得很好，我决定使用tracaRota方法构建从uma ponit到另一个的路由，它开始这样做，应用程序甚至不启动
11-30 10:45:28.836: E/AndroidRuntime(14114): FATAL EXCEPTION: main
11-30 10:45:28.836: E/AndroidRuntime(14114): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.aplicacaoteste1/com.example.aplicacaoteste1.Main}: java.lang.NullPointerException
11-30 10:45:28.836: E/AndroidRuntime(14114): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
11-30 10:45:28.836: E/AndroidRuntime(14114): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
11-30 10:45:28.836: E/AndroidRuntime(14114): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
11-30 10:45:28.836: E/AndroidRuntime(14114): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
11-30 10:45:28.836: E/AndroidRuntime(14114): at android.os.Handler.dispatchMessage(Handler.java:99)
11-30 10:45:28.836: E/AndroidRuntime(14114): at android.os.Looper.loop(Looper.java:123)
11-30 10:45:28.836: E/AndroidRuntime(14114): at android.app.ActivityThread.main(ActivityThread.java:4627)
11-30 10:45:28.836: E/AndroidRuntime(14114): at java.lang.reflect.Method.invokeNative(Native Method)
11-30 10:45:28.836: E/AndroidRuntime(14114): at java.lang.reflect.Method.invoke(Method.java:521)
11-30 10:45:28.836: E/AndroidRuntime(14114): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:858)
11-30 10:45:28.836: E/AndroidRuntime(14114): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
11-30 10:45:28.836: E/AndroidRuntime(14114): at dalvik.system.NativeStart.main(Native Method)
11-30 10:45:28.836: E/AndroidRuntime(14114): Caused by: java.lang.NullPointerException
11-30 10:45:28.836: E/AndroidRuntime(14114): at com.example.aplicacaoteste1.Main.tracaRota(Main.java:167)
11-30 10:45:28.836: E/AndroidRuntime(14114): at com.example.aplicacaoteste1.Main.onCreate(Main.java:77)
11-30 10:45:28.836: E/AndroidRuntime(14114): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
11-30 10:45:28.836: E/AndroidRuntime(14114): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
11-30 10:45:28.836: E/AndroidRuntime(14114): ... 11 more
package com.example.aplicacaoteste1;
import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.List;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.w3c.dom.Document;
import org.xml.sax.SAXException;
import android.content.Context;
import android.graphics.Color;
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.view.Menu;
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.MyLocationOverlay;
import com.google.android.maps.Overlay;
import com.google.android.maps.OverlayItem;
public class Main extends MapActivity {
private MapController mControl;
private MapView mapV;
private LocationManager lManager;
private MyLocationOverlay myLOverlay;
private MyOverlays itemizedOverlay;
@Override
protected void onCreate(Bundle bundle) {
super.onCreate(bundle);
setContentView(R.layout.activity_main);
mapV = (MapView) findViewById(R.id.mapView);
//mapV.displayZoomControls(true);
mapV.setBuiltInZoomControls(true);
//mapV.setSatellite(true);
mControl = mapV.getController();
mControl.setZoom(5);
lManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
lManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, new GeoUpdateHandler());
myLOverlay = new MyLocationOverlay(this, mapV);
mapV.getOverlays().add(myLOverlay);
List<Overlay> mapOverlays = mapV.getOverlays();
Drawable drawable = this.getResources().getDrawable(R.drawable.androidmarker);
PontoTurísticos pontoTuristico = new PontoTurísticos(drawable, this);
GeoPoint point1 = new GeoPoint(19240000,-99120000);
OverlayItem novoPontoTuristico = new OverlayItem(point1, "Hola, Mundo!", "I'm in Mexico City!");
GeoPoint point2 = new GeoPoint(-80535835, -348788191);
OverlayItem novoPontoTuristico2 = new OverlayItem(point2, "SJCC!", "Olá, tudo bem?!");
pontoTuristico.addOverlay(novoPontoTuristico);
pontoTuristico.addOverlay(novoPontoTuristico2);
mapOverlays.add(pontoTuristico);
tracaRota(myLOverlay.getMyLocation(), novoPontoTuristico2.getPoint(), Color.GREEN, mapV);
myLOverlay.runOnFirstFix(new Runnable() {
@Override
public void run() {
mapV.getController().animateTo(myLOverlay.getMyLocation());
}
});
//Drawable drawable = this.getResources().getDrawable(R.drawable.ic_launcher);
//itemizedOverlay = new MyOverlays(this, drawable);
//createMarker();
// double lat = -8.0556;
// double longi = 34.8911;
}
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
protected boolean isRouteDisplayed() {
return false;
}
public class GeoUpdateHandler implements LocationListener{
@Override
public void onLocationChanged(Location location) {
int lat = (int) (location.getLatitude());
int log = (int) (location.getLongitude());
GeoPoint point = new GeoPoint(lat, log);
//createMarker();
//mControl.animateTo(point);
mControl.setCenter(point);
}
@Override
public void onProviderDisabled(String arg0) {
}
@Override
public void onProviderEnabled(String arg0) {
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
}
//private void createMarker(){
// GeoPoint p = mapV.getMapCenter();
// OverlayItem overlayitem = new OverlayItem(p, "", "");
// itemizedOverlay.addOverlay(overlayitem);
// if(itemizedOverlay.size() < 0){
// mapV.getOverlays().add(itemizedOverlay);
// }
//}
protected void onResume(){
super.onResume();
myLOverlay.enableMyLocation();
myLOverlay.enableCompass();
}
protected void onPause(){
super.onPause();
myLOverlay.disableMyLocation();
myLOverlay.disableCompass();
}
private void tracaRota(GeoPoint src,GeoPoint dest, int color, MapView mV)
{
// connect to map web service
StringBuilder urlString = new StringBuilder();
urlString.append("http://maps.google.com/maps?f=d&hl=en");
urlString.append("&saddr=");//from
urlString.append( Double.toString((double)src.getLatitudeE6()/1.0E6 ));
urlString.append(",");
urlString.append( Double.toString((double)src.getLongitudeE6()/1.0E6 ));
urlString.append("&daddr=");//to
urlString.append( Double.toString((double)dest.getLatitudeE6()/1.0E6 ));
urlString.append(",");
urlString.append( Double.toString((double)dest.getLongitudeE6()/1.0E6 ));
urlString.append("&ie=UTF8&0&om=0&output=kml");
//Log.d("xxx","URL="+urlString.toString());
// get the kml (XML) doc. And parse it to get the coordinates(direction route).
Document doc = null;
HttpURLConnection urlConnection= null;
URL url = null;
try
{
url = new URL(urlString.toString());
urlConnection=(HttpURLConnection)url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.setDoOutput(true);
urlConnection.setDoInput(true);
urlConnection.connect();
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = dbf.newDocumentBuilder();
doc = db.parse(urlConnection.getInputStream());
if(doc.getElementsByTagName("GeometryCollection").getLength()>0)
{
//String path = doc.getElementsByTagName("GeometryCollection").item(0).getFirstChild().getFirstChild().getNodeName();
String path = doc.getElementsByTagName("GeometryCollection").item(0).getFirstChild().getFirstChild().getFirstChild().getNodeValue() ;
//Log.d("xxx","path="+ path);
String [] pairs = path.split(" ");
String[] lngLat = pairs[0].split(","); // lngLat[0]=longitude lngLat[1]=latitude lngLat[2]=height
// src
GeoPoint startGP = new GeoPoint((int)(Double.parseDouble(lngLat[1])*1E6),(int)(Double.parseDouble(lngLat[0])*1E6));
mV.getOverlays().add(new pontosRota(startGP,startGP,1));
GeoPoint gp1;
GeoPoint gp2 = startGP;
for(int i=1;i<pairs.length;i++) // the last one would be crash
{
lngLat = pairs[i].split(",");
gp1 = gp2;
// watch out! For GeoPoint, first:latitude, second:longitude
gp2 = new GeoPoint((int)(Double.parseDouble(lngLat[1])*1E6),(int)(Double.parseDouble(lngLat[0])*1E6));
mV.getOverlays().add(new pontosRota(gp1,gp2,2,color));
//Log.d("xxx","pair:" + pairs[i]);
}
mV.getOverlays().add(new pontosRota(dest,dest, 3)); // use the default color
}
}
catch (MalformedURLException e)
{
e.printStackTrace();
}
catch (IOException e)
{
e.printStackTrace();
}
catch (ParserConfigurationException e)
{
e.printStackTrace();
}
catch (SAXException e)
{
e.printStackTrace();
}
}
}
答案 0 :(得分：0)
似乎就在这一行：
tracaRota(myLOverlay.getMyLocation(), novoPontoTuristico2.getPoint(), Color.GREEN, mapV);
mLOverlay.getMyLocation返回null。
尝试将其移至myLOverlay.runOnFirstFix runner