问题
I recently got working with Google Maps API v2 on Android and stumbled upon another obstacle. I cannot figure out how to add an overlay such as in API v1 to display a marker on certain locations using lat and long. I also want it to start in the same town using long and lat. I so far added some code in for the starting position of map BUT it didn't work. I guess I should write it all in java instead of the XML layout but I don't know how to address SupportMapFragment to do anything.
This is main activity, I am using SUPPORTMAPFRAGMENT instead of MapFragment and would prefer not to switch.
package com.example.maps;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import com.google.android.gms.maps.SupportMapFragment;
public class Main extends FragmentActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
SupportMapFragment fragment = new SupportMapFragment();
getSupportFragmentManager().beginTransaction()
.add(android.R.id.content, fragment).commit();
}
}
This is XML
<?xml version="1.0" encoding="utf-8"?>
<fragment xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:map="http://schemas.android.com/apk/res-auto"
android:id="@+id/map"
android:name="com.google.android.gms.maps.SupportMapFragment"
android:layout_width="wrap_content"
android:layout_height="match_parent"
map:cameraBearing="112.5"
map:cameraTargetLat="-33.796923"
map:cameraTargetLng="150.922433"
map:cameraTilt="30"
map:cameraZoom="13"
map:mapType="normal"
map:uiCompass="false"
map:uiRotateGestures="true"
map:uiScrollGestures="false"
map:uiTiltGestures="true"
map:uiZoomControls="false"
map:uiZoomGestures="true" />
EDIT
New Java code( I excluded imports and package but they are all there. )
public class Main extends FragmentActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
SupportMapFragment fragment = new SupportMapFragment();
getSupportFragmentManager().beginTransaction()
.add(android.R.id.content, fragment).commit();
GoogleMap googleMap;
googleMap = ((SupportMapFragment)(getSupportFragmentManager().findFragmentById(R.id.map))).getMap();
LatLng latLng = new LatLng(-33.796923, 150.922433);
googleMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);
googleMap.addMarker(new MarkerOptions()
.position(latLng)
.title("My Spot")
.snippet("This is my spot!")
.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_AZURE)));
googleMap.getUiSettings().setCompassEnabled(true);
googleMap.getUiSettings().setZoomControlsEnabled(true);
googleMap.animateCamera(CameraUpdateFactory.newLatLngZoom(latLng, 10));
}
}
New errors
01-02 01:16:53.333: D/AndroidRuntime(916): Shutting down VM
01-02 01:16:53.333: W/dalvikvm(916): threadid=1: thread exiting with uncaught exception (group=0x40a70930)
01-02 01:16:53.363: E/AndroidRuntime(916): FATAL EXCEPTION: main
01-02 01:16:53.363: E/AndroidRuntime(916): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.maps/com.example.maps.Main}: java.lang.NullPointerException
01-02 01:16:53.363: E/AndroidRuntime(916): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
01-02 01:16:53.363: E/AndroidRuntime(916): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
01-02 01:16:53.363: E/AndroidRuntime(916): at android.app.ActivityThread.access$600(ActivityThread.java:141)
01-02 01:16:53.363: E/AndroidRuntime(916): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
01-02 01:16:53.363: E/AndroidRuntime(916): at android.os.Handler.dispatchMessage(Handler.java:99)
01-02 01:16:53.363: E/AndroidRuntime(916): at android.os.Looper.loop(Looper.java:137)
01-02 01:16:53.363: E/AndroidRuntime(916): at android.app.ActivityThread.main(ActivityThread.java:5039)
01-02 01:16:53.363: E/AndroidRuntime(916): at java.lang.reflect.Method.invokeNative(Native Method)
01-02 01:16:53.363: E/AndroidRuntime(916): at java.lang.reflect.Method.invoke(Method.java:511)
01-02 01:16:53.363: E/AndroidRuntime(916): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
01-02 01:16:53.363: E/AndroidRuntime(916): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
01-02 01:16:53.363: E/AndroidRuntime(916): at dalvik.system.NativeStart.main(Native Method)
01-02 01:16:53.363: E/AndroidRuntime(916): Caused by: java.lang.NullPointerException
01-02 01:16:53.363: E/AndroidRuntime(916): at com.example.maps.Main.onCreate(Main.java:19)
01-02 01:16:53.363: E/AndroidRuntime(916): at android.app.Activity.performCreate(Activity.java:5104)
01-02 01:16:53.363: E/AndroidRuntime(916): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
01-02 01:16:53.363: E/AndroidRuntime(916): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
01-02 01:16:53.363: E/AndroidRuntime(916): ... 11 more
回答1:
You can add a marker in the onCreate of your FragmentActivity.
GoogleMap googleMap;
googleMap = ((SupportMapFragment)(getSupportFragmentManager().findFragmentById(R.id.map))).getMap();
LatLng latLng = new LatLng(-33.796923, 150.922433);
googleMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);
googleMap.addMarker(new MarkerOptions()
.position(latLng)
.title("My Spot")
.snippet("This is my spot!")
.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_AZURE)));
googleMap.getUiSettings().setCompassEnabled(true);
googleMap.getUiSettings().setZoomControlsEnabled(true);
googleMap.animateCamera(CameraUpdateFactory.newLatLngZoom(latLng, 10));
The end to end solution would look like this for the layout...
<?xml version="1.0" encoding="utf-8"?>
<fragment xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/map"
android:name="com.google.android.gms.maps.SupportMapFragment"
android:layout_width="match_parent"
android:layout_height="match_parent" />
...the Activity like this...
public class NameOfYourActivity extends FragmentActivity {
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.nameOfYourLayout);
GoogleMap googleMap;
googleMap = ((SupportMapFragment)(getSupportFragmentManager().findFragmentById(R.id.map))).getMap();
LatLng latLng = new LatLng(-33.796923, 150.922433);
googleMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);
googleMap.addMarker(new MarkerOptions()
.position(latLng)
.title("My Spot")
.snippet("This is my spot!")
.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_AZURE)));
googleMap.getUiSettings().setCompassEnabled(true);
googleMap.getUiSettings().setZoomControlsEnabled(true);
googleMap.animateCamera(CameraUpdateFactory.newLatLngZoom(latLng, 10));
}
回答2:
https://developers.google.com/maps/documentation/android-api/groundoverlay
LatLng NEWARK = new LatLng(40.714086, -74.228697);
GroundOverlayOptions newarkMap = new GroundOverlayOptions()
.image(BitmapDescriptorFactory.fromResource(R.drawable.newark_nj_1922))
.position(NEWARK, 8600f, 6500f);
map.addGroundOverlay(newarkMap);
回答3:
Not sure if you still need a hand on this, but here is what worked for me.
Since you are loading the fragment into a container, it's taking time to load the fragment components into memory and hence the map is null. To remedy this, I grab and populate the map in the onAttachedToWindow() method of my activity while still creating and adding the fragment to the container in the onCreate method. This gives the fragment time to load since this event fires when the window has been loaded.
SupportMapFragment mMapFragment;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_map);
final FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
// Try to obtain the map from the SupportMapFragment.
mMapFragment = (SupportMapFragment) getSupportFragmentManager().findFragmentByTag(MAP_FRAG_NAME);
// Not found so make a new instance and add it to the transaction for swapping
if (mMapFragment == null) {
mMapFragment = SupportMapFragment.newInstance();
ft.add(R.id.fragment_container, mMapFragment, MAP_FRAG_NAME);
}
ft.commit();
}
@Override
public void onAttachedToWindow() {
// Load the map here such that the fragment has a chance to completely load or else the GoogleMap value may be null
GoogleMap googleMap;
googleMap = (mMapFragment).getMap();
LatLng latLng = new LatLng(-33.796923, 150.922433);
googleMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);
googleMap.addMarker(new MarkerOptions()
.position(latLng)
.title("My Spot")
.snippet("This is my spot!")
.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_AZURE)));
googleMap.getUiSettings().setCompassEnabled(true);
googleMap.getUiSettings().setZoomControlsEnabled(true);
googleMap.animateCamera(CameraUpdateFactory.newLatLngZoom(latLng, 10));
super.onAttachedToWindow();
}
hope this helps.
Regards, DMan
来源：https://stackoverflow.com/questions/14114131/how-to-add-overlay-in-google-maps-api-v2-android