我正在做一个面向Android地图的项目。我写了一些代码来显示两个地方之间的方向，但它只适用于较低的Android版本，如2.0,2.2等。它不适用于Android 4.0及更高版本。当我在Android 4.0中运行此代码时，它会显示IndexOutOfBoundsException。
我的班级
import java.io.InputStream;
import java.util.ArrayList;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.protocol.BasicHttpContext;
import org.apache.http.protocol.HttpContext;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Point;
import android.os.Bundle;
import android.widget.Button;
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;
public class LocationActivity extends MapActivity {
MapView mv;
MapController mc;
Button Save, Cancel;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.map_places);
MapView mv = (MapView)findViewById(R.id.mapView);
mv.setBuiltInZoomControls(true);
MapController mc = mv.getController();
ArrayList<GeoPoint> all_geo_points = getDirections(10.154929, 76.390316, 10.015861, 76.341867);
GeoPoint moveTo = all_geo_points.get(0);
mc.animateTo(moveTo);
mc.setZoom(12);
mv.getOverlays().add(new MyOverlay(all_geo_points));
}
public class MyOverlay extends Overlay {
private ArrayList<GeoPoint> all_geo_points;
public MyOverlay(ArrayList<GeoPoint> allGeoPoints) {
super();
this.all_geo_points = allGeoPoints;
}
@Override
public boolean draw(Canvas canvas, MapView mv, boolean shadow, long when) {
super.draw(canvas, mv, shadow);
drawPath(mv, canvas);
return true;
}
public void drawPath(MapView mv, Canvas canvas) {
int xPrev = -1, yPrev = -1, xNow = -1, yNow = -1;
Paint paint = new Paint();
paint.setColor(Color.BLUE);
paint.setStyle(Paint.Style.FILL_AND_STROKE);
paint.setStrokeWidth(4);
paint.setAlpha(100);
if (all_geo_points != null) for (int i = 0; i < all_geo_points.size() - 4; i++) {
GeoPoint gp = all_geo_points.get(i);
Point point = new Point();
mv.getProjection().toPixels(gp, point);
xNow = point.x;
yNow = point.y;
if (xPrev != -1) {
canvas.drawLine(xPrev, yPrev, xNow, yNow, paint);
}
xPrev = xNow;
yPrev = yNow;
}
}
}
public static ArrayList<GeoPoint> getDirections(double lat1, double lon1, double lat2, double lon2) {
String url = "http://maps.googleapis.com/maps/api/directions/xml?origin=" + lat1 + "," + lon1 + "&destination=" + lat2 + "," + lon2
+ "&sensor=false&units=metric";
String tag[] = {"lat", "lng"};
ArrayList<GeoPoint> list_of_geopoints = new ArrayList<GeoPoint>();
HttpResponse response = null;
try {
HttpClient httpClient = new DefaultHttpClient();
HttpContext localContext = new BasicHttpContext();
HttpPost httpPost = new HttpPost(url);
response = httpClient.execute(httpPost, localContext);
InputStream in = response.getEntity().getContent();
DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
Document doc = builder.parse(in);
if (doc != null) {
NodeList nl1, nl2;
nl1 = doc.getElementsByTagName(tag[0]);
nl2 = doc.getElementsByTagName(tag[1]);
if (nl1.getLength() > 0) {
list_of_geopoints = new ArrayList<GeoPoint>();
for (int i = 0; i < nl1.getLength(); i++) {
Node node1 = nl1.item(i);
Node node2 = nl2.item(i);
double lat = Double.parseDouble(node1.getTextContent());
double lng = Double.parseDouble(node2.getTextContent());
list_of_geopoints.add(new GeoPoint((int) (lat * 1E6), (int) (lng * 1E6)));
}
} else {
// No points found
}
}
} catch (Exception e) {
e.printStackTrace();
}
return list_of_geopoints;
}
@Override
protected boolean isRouteDisplayed() {
// TODO Auto-generated method stub
return true;
}
}
我的logcat
03-01 19:05:19.180: E/AndroidRuntime(2839): FATAL EXCEPTION: main
03-01 19:05:19.180: E/AndroidRuntime(2839): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.kodspider.parkon/com.kodspider.parkon.LocationActivity}: java.lang.IndexOutOfBoundsException: Invalid index 0, size is 0
03-01 19:05:19.180: E/AndroidRuntime(2839): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
03-01 19:05:19.180: E/AndroidRuntime(2839): at android.app.ActivityThread.startActivityNow(ActivityThread.java:1900)
03-01 19:05:19.180: E/AndroidRuntime(2839): at android.app.LocalActivityManager.moveToState(LocalActivityManager.java:135)
03-01 19:05:19.180: E/AndroidRuntime(2839): at android.app.LocalActivityManager.startActivity(LocalActivityManager.java:347)
03-01 19:05:19.180: E/AndroidRuntime(2839): at android.widget.TabHost$IntentContentStrategy.getContentView(TabHost.java:694)
03-01 19:05:19.180: E/AndroidRuntime(2839): at android.widget.TabHost.setCurrentTab(TabHost.java:358)
03-01 19:05:19.180: E/AndroidRuntime(2839): at android.widget.TabHost$2.onTabSelectionChanged(TabHost.java:150)
03-01 19:05:19.180: E/AndroidRuntime(2839): at android.widget.TabWidget$TabClickListener.onClick(TabWidget.java:546)
03-01 19:05:19.180: E/AndroidRuntime(2839): at android.view.View.performClick(View.java:4084)
03-01 19:05:19.180: E/AndroidRuntime(2839): at android.view.View$PerformClick.run(View.java:16966)
03-01 19:05:19.180: E/AndroidRuntime(2839): at android.os.Handler.handleCallback(Handler.java:615)
03-01 19:05:19.180: E/AndroidRuntime(2839): at android.os.Handler.dispatchMessage(Handler.java:92)
03-01 19:05:19.180: E/AndroidRuntime(2839): at android.os.Looper.loop(Looper.java:137)
03-01 19:05:19.180: E/AndroidRuntime(2839): at android.app.ActivityThread.main(ActivityThread.java:4745)
03-01 19:05:19.180: E/AndroidRuntime(2839): at java.lang.reflect.Method.invokeNative(Native Method)
03-01 19:05:19.180: E/AndroidRuntime(2839): at java.lang.reflect.Method.invoke(Method.java:511)
03-01 19:05:19.180: E/AndroidRuntime(2839): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
03-01 19:05:19.180: E/AndroidRuntime(2839): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
03-01 19:05:19.180: E/AndroidRuntime(2839): at dalvik.system.NativeStart.main(Native Method)
03-01 19:05:19.180: E/AndroidRuntime(2839): Caused by: java.lang.IndexOutOfBoundsException: Invalid index 0, size is 0
03-01 19:05:19.180: E/AndroidRuntime(2839): at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:251)
03-01 19:05:19.180: E/AndroidRuntime(2839): at java.util.ArrayList.get(ArrayList.java:304)
03-01 19:05:19.180: E/AndroidRuntime(2839): at com.kodspider.parkon.LocationActivity.onCreate(LocationActivity.java:43)
03-01 19:05:19.180: E/AndroidRuntime(2839): at android.app.Activity.performCreate(Activity.java:5008)
03-01 19:05:19.180: E/AndroidRuntime(2839): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
03-01 19:05:19.180: E/AndroidRuntime(2839): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
03-01 19:05:19.180: E/AndroidRuntime(2839): ... 18 more
答案 0 :(得分：3)
所以，基本上，getDirections（）返回一个空的ArrayList，然后你试图访问它的第一个项目。
尝试理解为什么你的方法返回一个空集并修复它。
答案 1 :(得分：0)
你有例外 com.kodspider.parkon.LocationActivity.onCreate（LocationActivity.java:43）
我认为它遵循以下代码行：
ArrayList<GeoPoint> all_geo_points = getDirections(10.154929, 76.390316, 10.015861, 76.341867);
GeoPoint moveTo = all_geo_points.get(0);
所以Method getDirections返回一个空数组。 尝试：
if(all_geo_points.size()>0){
GeoPoint moveTo = all_geo_points.get(0);
mc.animateTo(moveTo);
mc.setZoom(12);
mv.getOverlays().add(new MyOverlay(all_geo_points));
}
答案 2 :(得分：0)
我为更高版本的Android平台找到了我的问题的答案我们必须使用AsyncTask类作为后台线程
答案 3 :(得分：0)
使用以下代码......
public static JSONObject getLocationInfo(String origin, String dest) {
StringBuilder stringBuilder = new StringBuilder();
try {
origin = origin.replaceAll(" ", "%20");
dest = dest.replaceAll(" ", "%20");
HttpPost httppost = new HttpPost(
"http://maps.googleapis.com/maps/api/directions/json?origin="
+ origin + "&destination=" + dest + "&sensor=false");
// http://maps.googleapis.com/maps/api/directions/json?origin=Chicago,IL&destination=Los+Angeles,CA&sensor=false
Log.i("httppost",
"http://maps.googleapis.com/maps/api/directions/json?origin="
+ origin + "&destination=" + dest + "&sensor=false");
HttpClient client = new DefaultHttpClient();
HttpResponse response;
stringBuilder = new StringBuilder();
response = client.execute(httppost);
HttpEntity entity = response.getEntity();
InputStream stream = entity.getContent();
int b;
while ((b = stream.read()) != -1) {
stringBuilder.append((char) b);
}
} catch (ClientProtocolException e) {
Log.i("Ex1", e.getMessage());
} catch (IOException e) {
Log.i("Ex2", e.getMessage());
}
JSONObject jsonObject = new JSONObject();
try {
jsonObject = new JSONObject(stringBuilder.toString());
Log.i("JSON Length", "" + jsonObject.length());
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return jsonObject;
}