我是Android编程的新手，我正在尝试在互联网上关注如何在Android上制作谷歌地图驾驶方向的一些教程。但不知怎的，代码没有用，虽然我的eclipse没有在代码上显示任何错误。如果这段代码有问题，任何人都可以提供帮助吗？
这是我的MapDirectionActivity
package my.map.direction;
import java.net.HttpURLConnection;
//import java.net.URI;
import java.net.URL;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
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 android.app.Activity;
import android.os.Bundle;
import android.util.Log;
public class MapDirectionActivity extends MapActivity {
MapView myMapView = null;
MapController myMc = null;
GeoPoint geoPoint = null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
myMapView = (MapView) findViewById(R.id.mapView);
geoPoint = null;
myMapView.setSatellite(false);
String htw = "-6.3039,106.8267";
String storkower = "-6.29436,106.8859";
String pairs[] = getDirectionData(htw, storkower);
String[] lngLat = pairs[0].split(",");
//starting point
GeoPoint startGP = new GeoPoint((int) (Double.parseDouble(lngLat[1])*1E6), (int)(Double.parseDouble(lngLat[0])*1E6));
myMc = myMapView.getController();
geoPoint = startGP;
myMc.setCenter(geoPoint);
myMc.setZoom(14);
myMapView.getOverlays().add(new DirectionPathOverlay(startGP, startGP));
GeoPoint gp1;
GeoPoint gp2 = startGP;
for(int i = 1; i<pairs.length;i++){
lngLat = pairs[i].split(",");
gp1 = gp2;
gp2 = new GeoPoint((int)(Double.parseDouble(lngLat[1])*1E6), (int)(Double.parseDouble(lngLat[0])*1E6));
myMapView.getOverlays().add(new DirectionPathOverlay(gp1,gp2));
Log.d("xxx","pair"+pairs[i]);
}
myMapView.getOverlays().add(new DirectionPathOverlay(gp2, gp2));
myMapView.getController().animateTo(startGP);
myMapView.setBuiltInZoomControls(true);
myMapView.displayZoomControls(true);
}
@Override
protected boolean isRouteDisplayed(){
return false;
}
private String[] getDirectionData(String srcPlace, String destPlace){
String urlString = "http://maps.google.com/maps?f=d&hl=en&saddr="
+ srcPlace + "&daddr=" + destPlace
+ "&ie=UTF8&0&om=0&output=kml";
Log.d("URL",urlString);
Document doc = null;
HttpURLConnection urlConnection = null;
URL url = null;
String pathContent = "";
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());
}catch(Exception e){
}
NodeList nl = doc.getElementsByTagName("LineString");
for(int s=0; s< nl.getLength();s++){
Node rootNode = nl.item(s);
NodeList configItems = rootNode.getChildNodes();
for(int x=0;x<configItems.getLength();x++){
Node lineStringNode = configItems.item(x);
NodeList path = lineStringNode.getChildNodes();
pathContent = path.item(0).getNodeValue();
}
}
String[] tempContent = pathContent.split(" ");
return tempContent;
}
}
我的DirectionPathOverlay
public class DirectionPathOverlay extends Overlay{
private GeoPoint gp1;
private GeoPoint gp2;
public DirectionPathOverlay(GeoPoint gp1, GeoPoint gp2){
this.gp1 = gp1;
this.gp2 = gp2;
}
@Override
public boolean draw(Canvas canvas, MapView mapView, boolean shadow, long when){
Projection projection = mapView.getProjection();
if(shadow == false){
Paint paint = new Paint();
paint.setAntiAlias(true);
Point point = new Point();
projection.toPixels(gp1, point);
paint.setColor(Color.BLUE);
Point point2 = new Point();
projection.toPixels(gp2, point2);
paint.setStrokeWidth(3);
canvas.drawLine((float) point.x, (float) point.y, (float) point2.x, (float) point2.y, paint);
}
return super.draw(canvas, mapView, shadow, when);
}
@Override
public void draw(Canvas canvas, MapView mapView, boolean shadow){
super.draw(canvas, mapView, shadow);
}
}
我在logcat上遇到以下错误
05-02 08:51:09.972: I/dalvikvm(629): threadid=3: reacting to signal 3
05-02 08:51:09.982: I/dalvikvm(629): Wrote stack traces to '/data/anr/traces.txt'
05-02 08:51:10.062: D/URL(629): http://maps.google.com/maps?f=d&hl=en&saddr=52.458402,13.526616&daddr=52.523559,13.475826&ie=UTF8&0&om=0&output=kml
05-02 08:51:10.082: D/AndroidRuntime(629): Shutting down VM
05-02 08:51:10.102: W/dalvikvm(629): threadid=1: thread exiting with uncaught exception (group=0x409c01f8)
05-02 08:51:10.122: E/AndroidRuntime(629): FATAL EXCEPTION: main
05-02 08:51:10.122: E/AndroidRuntime(629): java.lang.RuntimeException: Unable to start activity ComponentInfo{my.google.maps/my.google.maps.MapsTestActivity}: java.lang.NullPointerException
05-02 08:51:10.122: E/AndroidRuntime(629): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
05-02 08:51:10.122: E/AndroidRuntime(629): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
05-02 08:51:10.122: E/AndroidRuntime(629): at android.app.ActivityThread.access$600(ActivityThread.java:123)
05-02 08:51:10.122: E/AndroidRuntime(629): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
05-02 08:51:10.122: E/AndroidRuntime(629): at android.os.Handler.dispatchMessage(Handler.java:99)
05-02 08:51:10.122: E/AndroidRuntime(629): at android.os.Looper.loop(Looper.java:137)
05-02 08:51:10.122: E/AndroidRuntime(629): at android.app.ActivityThread.main(ActivityThread.java:4424)
05-02 08:51:10.122: E/AndroidRuntime(629): at java.lang.reflect.Method.invokeNative(Native Method)
05-02 08:51:10.122: E/AndroidRuntime(629): at java.lang.reflect.Method.invoke(Method.java:511)
05-02 08:51:10.122: E/AndroidRuntime(629): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
05-02 08:51:10.122: E/AndroidRuntime(629): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
05-02 08:51:10.122: E/AndroidRuntime(629): at dalvik.system.NativeStart.main(Native Method)
05-02 08:51:10.122: E/AndroidRuntime(629): Caused by: java.lang.NullPointerException
05-02 08:51:10.122: E/AndroidRuntime(629): at my.google.maps.MapsTestActivity.getDirectionData(MapsTestActivity.java:100)
05-02 08:51:10.122: E/AndroidRuntime(629): at my.google.maps.MapsTestActivity.onCreate(MapsTestActivity.java:38)
05-02 08:51:10.122: E/AndroidRuntime(629): at android.app.Activity.performCreate(Activity.java:4465)
05-02 08:51:10.122: E/AndroidRuntime(629): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
05-02 08:51:10.122: E/AndroidRuntime(629): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
05-02 08:51:10.122: E/AndroidRuntime(629): ... 11 more
05-02 08:51:10.152: D/dalvikvm(629): GC_CONCURRENT freed 206K, 5% free 5848K/6151K, paused 5ms+4ms
05-02 08:51:10.172: W/CursorWrapperInner(629): Cursor finalized without prior close()
05-02 08:51:10.172: W/CursorWrapperInner(629): Cursor finalized without prior close()
05-02 08:51:10.472: I/dalvikvm(629): threadid=3: reacting to signal 3
05-02 08:51:10.482: I/dalvikvm(629): Wrote stack traces to '/data/anr/traces.txt'
05-02 08:51:10.702: I/dalvikvm(629): threadid=3: reacting to signal 3
05-02 08:51:10.702: I/dalvikvm(629): Wrote stack traces to '/data/anr/traces.txt'
05-02 08:51:12.482: I/Process(629): Sending signal. PID: 629 SIG: 9
05-02 09:05:07.352: I/dalvikvm(647): threadid=3: reacting to signal 3
05-02 09:05:07.372: I/dalvikvm(647): Wrote stack traces to '/data/anr/traces.txt'
05-02 09:05:07.802: I/dalvikvm(647): threadid=3: reacting to signal 3
05-02 09:05:07.832: I/dalvikvm(647): Wrote stack traces to '/data/anr/traces.txt'
05-02 09:05:07.942: D/URL(647): http://maps.google.com/maps?f=d&hl=en&saddr=52.458402,13.526616&daddr=52.523559,13.475826&ie=UTF8&0&om=0&output=kml
05-02 09:05:07.972: D/AndroidRuntime(647): Shutting down VM
05-02 09:05:07.972: W/dalvikvm(647): threadid=1: thread exiting with uncaught exception (group=0x409c01f8)
05-02 09:05:07.982: E/AndroidRuntime(647): FATAL EXCEPTION: main
05-02 09:05:07.982: E/AndroidRuntime(647): java.lang.RuntimeException: Unable to start activity ComponentInfo{my.google.maps/my.google.maps.MapsTestActivity}: java.lang.NullPointerException
05-02 09:05:07.982: E/AndroidRuntime(647): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
05-02 09:05:07.982: E/AndroidRuntime(647): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
05-02 09:05:07.982: E/AndroidRuntime(647): at android.app.ActivityThread.access$600(ActivityThread.java:123)
05-02 09:05:07.982: E/AndroidRuntime(647): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
05-02 09:05:07.982: E/AndroidRuntime(647): at android.os.Handler.dispatchMessage(Handler.java:99)
05-02 09:05:07.982: E/AndroidRuntime(647): at android.os.Looper.loop(Looper.java:137)
05-02 09:05:07.982: E/AndroidRuntime(647): at android.app.ActivityThread.main(ActivityThread.java:4424)
05-02 09:05:07.982: E/AndroidRuntime(647): at java.lang.reflect.Method.invokeNative(Native Method)
05-02 09:05:07.982: E/AndroidRuntime(647): at java.lang.reflect.Method.invoke(Method.java:511)
05-02 09:05:07.982: E/AndroidRuntime(647): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
05-02 09:05:07.982: E/AndroidRuntime(647): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
05-02 09:05:07.982: E/AndroidRuntime(647): at dalvik.system.NativeStart.main(Native Method)
05-02 09:05:07.982: E/AndroidRuntime(647): Caused by: java.lang.NullPointerException
05-02 09:05:07.982: E/AndroidRuntime(647): at my.google.maps.MapsTestActivity.getDirectionData(MapsTestActivity.java:100)
05-02 09:05:07.982: E/AndroidRuntime(647): at my.google.maps.MapsTestActivity.onCreate(MapsTestActivity.java:38)
05-02 09:05:07.982: E/AndroidRuntime(647): at android.app.Activity.performCreate(Activity.java:4465)
05-02 09:05:07.982: E/AndroidRuntime(647): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
05-02 09:05:07.982: E/AndroidRuntime(647): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
05-02 09:05:07.982: E/AndroidRuntime(647): ... 11 more
05-02 09:05:08.032: D/dalvikvm(647): GC_CONCURRENT freed 206K, 5% free 5848K/6151K, paused 4ms+7ms
05-02 09:05:08.032: W/CursorWrapperInner(647): Cursor finalized without prior close()
05-02 09:05:08.032: W/CursorWrapperInner(647): Cursor finalized without prior close()
05-02 09:05:08.302: I/dalvikvm(647): threadid=3: reacting to signal 3
05-02 09:05:08.342: I/dalvikvm(647): Wrote stack traces to '/data/anr/traces.txt'
05-02 09:05:08.632: I/dalvikvm(647): threadid=3: reacting to signal 3
05-02 09:05:08.654: I/dalvikvm(647): Wrote stack traces to '/data/anr/traces.txt'
我已经检查了我的main.xml和manifest.xml以及运行谷歌地图的任何必要设置，我已经在我的另一个mapactivity programm上测试了xml的类似设置并且它正常工作，所以我不认为我的apikey没有工作
答案 0 :(得分：0)
如果你查看日志，你会看到：
引起：java.lang.NullPointerException 05-02 09：05：07.982：E / AndroidRuntime（647）：at my.google.maps.MapsTestActivity.getDirectionData（MapsTestActivity.java:100）
所以问题是函数getDirectionData返回NULL。