我正在开发一个显示带有多个标记的地图的 Android 应用程序。对于相同的代码，当我使用新应用程序运行时它可以正常工作，但是当我将它与我的应用程序集成时它就不行了。它给了我一个异常/错误，如下所示：
07-24 14:19:55.737: ERROR/AndroidRuntime(1645): FATAL EXCEPTION: main
07-24 14:19:55.737: ERROR/AndroidRuntime(1645): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.maps/com.maps.DisplayMap}: java.lang.NullPointerException
07-24 14:19:55.737: ERROR/AndroidRuntime(1645): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
07-24 14:19:55.737: ERROR/AndroidRuntime(1645): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
07-24 14:19:55.737: ERROR/AndroidRuntime(1645): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
07-24 14:19:55.737: ERROR/AndroidRuntime(1645): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
07-24 14:19:55.737: ERROR/AndroidRuntime(1645): at android.os.Handler.dispatchMessage(Handler.java:99)
07-24 14:19:55.737: ERROR/AndroidRuntime(1645): at android.os.Looper.loop(Looper.java:123)
07-24 14:19:55.737: ERROR/AndroidRuntime(1645): at android.app.ActivityThread.main(ActivityThread.java:4627)
07-24 14:19:55.737: ERROR/AndroidRuntime(1645): at java.lang.reflect.Method.invokeNative(Native Method)
07-24 14:19:55.737: ERROR/AndroidRuntime(1645): at java.lang.reflect.Method.invoke(Method.java:521)
07-24 14:19:55.737: ERROR/AndroidRuntime(1645): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
07-24 14:19:55.737: ERROR/AndroidRuntime(1645): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
07-24 14:19:55.737: ERROR/AndroidRuntime(1645): at dalvik.system.NativeStart.main(Native Method)
07-24 14:19:55.737: ERROR/AndroidRuntime(1645): Caused by: java.lang.NullPointerException
07-24 14:19:55.737: ERROR/AndroidRuntime(1645): at com.maps.DisplayMap.onCreate(DisplayMap.java:32)
07-24 14:19:55.737: ERROR/AndroidRuntime(1645): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
07-24 14:19:55.737: ERROR/AndroidRuntime(1645): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
我的代码：
package com.maps;
import java.util.ArrayList;
import java.util.List;
import android.graphics.Canvas;
import android.graphics.Point;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.RelativeLayout;
import android.widget.TextView;
import com.google.android.maps.GeoPoint;
import com.google.android.maps.ItemizedOverlay;
import com.google.android.maps.MapActivity;
import com.google.android.maps.MapView;
import com.google.android.maps.MyLocationOverlay;
import com.google.android.maps.OverlayItem;
public class DisplayMap extends MapActivity {
private MapView map=null;
private MyLocationOverlay me=null;
private SitesOverlay sites=null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
map=(MapView)findViewById(R.id.map);
map.getController().setCenter(getPoint(19.159646,
72.995664));
map.getController().setZoom(17);
map.setBuiltInZoomControls(true);
sites=new SitesOverlay();
map.getOverlays().add(sites);
me=new MyLocationOverlay(this, map);
map.getOverlays().add(me);
}
@Override
public void onResume() {
super.onResume();
me.enableCompass();
}
@Override
public void onPause() {
super.onPause();
me.disableCompass();
}
@Override
protected boolean isRouteDisplayed() {
return(false);
}
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_S) {
map.setSatellite(!map.isSatellite());
return(true);
}
else if (keyCode == KeyEvent.KEYCODE_Z) {
map.displayZoomControls(true);
return(true);
}
else if (keyCode == KeyEvent.KEYCODE_H) {
sites.toggleHeart();
return(true);
}
return(super.onKeyDown(keyCode, event));
}
private GeoPoint getPoint(double lat, double lon) {
return(new GeoPoint((int)(lat*1000000.0),
(int)(lon*1000000.0)));
}
private class SitesOverlay extends ItemizedOverlay<CustomItem> {
private Drawable heart=null;
private List<CustomItem> items=new ArrayList<CustomItem>();
private PopupPanel panel=new PopupPanel(R.layout.popup);
public SitesOverlay() {
super(null);
heart=getMarker(R.drawable.heart_full);
items.add(new CustomItem(getPoint(40.748963847316034,
-73.96807193756104),
"","",
getMarker(R.drawable.blue_full_marker),
heart));
items.add(new CustomItem(getPoint(40.76866299974387,
-73.98268461227417),
"",
"",
getMarker(R.drawable.orange_full_marker),
heart));
items.add(new CustomItem(getPoint(40.765136435316755,
-73.97989511489868),
"",
"",
getMarker(R.drawable.green_full_marker),
heart));
items.add(new CustomItem(getPoint(40.70686417491799,
-74.01572942733765),
"",
"",
getMarker(R.drawable.purple_full_marker),
heart));
populate();
}
@Override
protected CustomItem createItem(int i) {
return(items.get(i));
}
@Override
public void draw(Canvas canvas, MapView mapView,
boolean shadow) {
super.draw(canvas, mapView, shadow);
}
@Override
protected boolean onTap(int i) {
OverlayItem item=getItem(i);
GeoPoint geo=item.getPoint();
Point pt=map.getProjection().toPixels(geo, null);
View view=panel.getView();
((TextView)view.findViewById(R.id.latitude))
.setText(String.valueOf(geo.getLatitudeE6()/1000000.0));
((TextView)view.findViewById(R.id.longitude))
.setText(String.valueOf(geo.getLongitudeE6()/1000000.0));
((TextView)view.findViewById(R.id.x))
.setText(String.valueOf(pt.x));
((TextView)view.findViewById(R.id.y))
.setText(String.valueOf(pt.y));
panel.show(pt.y*2>map.getHeight());
return(true);
}
@Override
public int size() {
return(items.size());
}
void toggleHeart() {
CustomItem focus=getFocus();
if (focus!=null) {
focus.toggleHeart();
}
map.invalidate();
}
private Drawable getMarker(int resource) {
Drawable marker=getResources().getDrawable(resource);
marker.setBounds(0, 0, marker.getIntrinsicWidth(),
marker.getIntrinsicHeight());
boundCenter(marker);
return(marker);
}
}
class PopupPanel {
View popup;
boolean isVisible=false;
PopupPanel(int layout) {
ViewGroup parent=(ViewGroup)map.getParent();
popup=getLayoutInflater().inflate(layout, parent, false);
popup.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
hide();
}
});
}
View getView() {
return(popup);
}
void show(boolean alignTop) {
RelativeLayout.LayoutParams lp=new RelativeLayout.LayoutParams(
RelativeLayout.LayoutParams.WRAP_CONTENT,
RelativeLayout.LayoutParams.WRAP_CONTENT
);
if (alignTop) {
lp.addRule(RelativeLayout.ALIGN_PARENT_TOP);
lp.setMargins(0, 20, 0, 0);
}
else {
lp.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM);
lp.setMargins(0, 0, 0, 60);
}
hide();
((ViewGroup)map.getParent()).addView(popup, lp);
isVisible=true;
}
void hide() {
if (isVisible) {
isVisible=false;
((ViewGroup)popup.getParent()).removeView(popup);
}
}
}
class CustomItem extends OverlayItem {
Drawable marker=null;
boolean isHeart=false;
Drawable heart=null;
CustomItem(GeoPoint pt, String name, String snippet,
Drawable marker, Drawable heart) {
super(pt, name, snippet);
this.marker=marker;
this.heart=heart;
}
@Override
public Drawable getMarker(int stateBitset) {
Drawable result=(isHeart ? heart : marker);
setState(result, stateBitset);
return(result);
}
void toggleHeart() {
isHeart=!isHeart;
}
}
}