public class AppClass extends Application{
@Override
 public void onTerminate() {
  // TODO Auto-generated method stub
  super.onTerminate();
 }

 GeoPoint[] geopoint;
 GeoPoint singlePoint;
 
 @Override
 public void onCreate() {
  // TODO Auto-generated method stub
  super.onCreate();
 }

 public GeoPoint[] getGeopoint() {
  return geopoint;
 }

 public void setGeopoint(GeoPoint[] point) {
  this.geopoint = new GeoPoint[point.length];
  
  for(int i = 1; i < point.length -1; i++)
   this.geopoint[i] = point[i];
 }

 public GeoPoint getSinglePoint() {
  return singlePoint;
 }

 public void setSinglePoint(GeoPoint Point) {
  this.singlePoint = new GeoPoint(Point.getLatitudeE6(), Point.getLongitudeE6());
  
 } 
}

public class GetGeoPoint extends Activity {

 AppClass app;
 GeoPoint[] geopoint;

 public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.main);

  app = (AppClass)getApplication();
 }

 public void setLocation(){
 
 
 .....geopoint는 얻음.. 배열 확인 됨

 app.setGeopoint(geopoint);// 여기서 보니까 app가 아무것도 가지지 않은 null입니다...그래서 geopoint를 set 하지 못하고 nullpointException으로 나옴
 }
}

public class HelloItemizedOverlay extends ItemizedOverlay<OverlayItem> {

 GetGeoPoint point;
 AppClass app;

 public HelloItemizedOverlay(Drawable defaultMarker) {
  super(boundCenterBottom(defaultMarker));
  // TODO Auto-generated constructor stub

  app = (AppClass)getApplication();
 }

 public HelloItemizedOverlay(Drawable defaultMarker, Context context) 
 {
  super(boundCenterBottom(defaultMarker));
  mContext = context;

  app = (AppClass)getApplication();
  
 }
 
 protected boolean onTap(int index) 
 { 
  
  
  OverlayItem item = mOverlays.get(index);
  AlertDialog.Builder dialog = new AlertDialog.Builder(mContext);
  dialog.setTitle(item.getTitle());
  dialog.setMessage(item.getSnippet());
  
  app.setSinglePoint(item.getPoint()); // 여기도 여깃 app가 null만 가짐..
 }
}

생성을 잘못한건지 전역변수로 전혀 사용을 못하겠네요....

꼭 써야 대는데.....

고수님들 꼭 알려주세요....