我在我的应用程序中使用 mapquest android，我可以显示标记，但我希望每次只能显示两个标记，因此如果我已经显示了两个，请删除现有标记。有谁知道我该怎么做？这是我的代码
MainActivity.java
public class MainActivity extends NavigationIntentDemo {
ArrayList<GeoPoint> points = new ArrayList<GeoPoint>();
ArrayList<GeoPoint> routeData = new ArrayList<GeoPoint>();
JSONParser parser = new JSONParser();
/**
* Initialize the map.
*/
@Override
protected void init() {
setupMapView(new GeoPoint(40.25f, 116.5f), 12);
TouchOverlay overlay = new TouchOverlay();
map.getOverlays().add(overlay);
}
/**
* Construct a simple line overlay to display on the map and add a OverlayTapListener
* to respond to tap events.
*
*/
private void showLineOverlayWithPoints(ArrayList<GeoPoint> routeData) {
Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setColor(Color.RED);
paint.setAlpha(100);
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeJoin(Paint.Join.ROUND);
paint.setStrokeCap(Paint.Cap.ROUND);
paint.setStrokeWidth(10);
LineOverlay line = new LineOverlay(paint);
line.setData(routeData);
line.setShowPoints(true, null);
line.setKey("Line #2");
line.setTouchEventListener(new LineOverlay.OverlayTouchEventListener() {
@Override
public void onTouch(MotionEvent evt, MapView mapView) {
Toast.makeText(getApplicationContext(), "Line Touch!", Toast.LENGTH_SHORT).show();
}
});
this.map.getOverlays().add(line);
this.map.invalidate();
}
/**
* Crude way to launch navigation to various locations based on clicking on the map.
*
*/
private class TouchOverlay extends Overlay {
@Override
public boolean onTouchEvent(MotionEvent event, final MapView mapView) {
Drawable icon = getResources().getDrawable(R.drawable.location_marker);
DefaultItemizedOverlay poiOverlay = new DefaultItemizedOverlay(icon);
if(event.getAction() == MotionEvent.ACTION_DOWN) {
GeoPoint p = mapView.getProjection().fromPixels((int)event.getX(), (int)event.getY());
Toast.makeText(getApplicationContext(), p.getLatitude() + "," + p.getLongitude(), Toast.LENGTH_LONG).show();
if(points.size()<2) {
points.add(p);
// set GeoPoints and title/snippet to be used in the annotation view
poiOverlay.addItem(new OverlayItem(p, "blabla", "blabla"));
if (points.size() == 2) {
routeData = parser.getRoute( points.get(0).getLongitude(),
points.get(0).getLatitude(),
points.get(1).getLongitude(),
points.get(1).getLatitude(),
"SPS");
if (routeData != null)
showLineOverlayWithPoints(routeData);
else
Log.e("ERROR","Route data error");
} else exit(0);
/* poiOverlay.setOnFocusChangeListener(new ItemizedOverlay.OnFocusChangeListener() {
@Override
public void onFocusChanged(ItemizedOverlay overlay, OverlayItem newFocus) {
// when focused item changes, recenter map and show info
map.getController().animateTo(newFocus.getPoint());
Toast.makeText(map.getContext().getApplicationContext(), newFocus.getTitle() + ": " +
newFocus.getSnippet(), Toast.LENGTH_SHORT).show();
}
});*/
map.getOverlays().add(poiOverlay);
return true;
}
else {
points.clear();
}
}
return false;
}
private void exit(int i) {
// TODO Auto-generated method stub
}
}
}
NavigationIntentDemo
public class NavigationIntentDemo extends MapActivity {
protected MapView map;
protected MyLocationOverlay myLocationOverlay;
protected Button followMeButton;
/**
* Called when the activity is first created.
*
*/
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(getLayoutId());
followMeButton=(Button)findViewById(R.id.followMeButton);
followMeButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
myLocationOverlay.setFollowing(true);
}
});
setupMapView(new GeoPoint(40.25f, 116.5f), 12);
setupMyLocation();
init();
}
/**
* Initialize the view.
*/
protected void init() {
this.setupMapView(new GeoPoint(40.25f, 116.5f), 12);
}
protected void setupMyLocation() {
this.myLocationOverlay = new MyLocationOverlay(this, map);
myLocationOverlay.enableMyLocation();
myLocationOverlay.runOnFirstFix(new Runnable() {
@Override
public void run() {
GeoPoint currentLocation = myLocationOverlay.getMyLocation();
map.getController().animateTo(currentLocation);
map.getController().setZoom(14);
map.getOverlays().add(myLocationOverlay);
myLocationOverlay.setFollowing(true);
}
});
}
/**
* This will set up a basic MapQuest map with zoom controls
*/
protected void setupMapView(GeoPoint pt, int zoom) {
this.map = (MapView) findViewById(R.id.map);
// set the zoom level
map.getController().setZoom(zoom);
// set the center point
map.getController().setCenter(pt);
// enable the zoom controls
map.setBuiltInZoomControls(true);
}
/**
* Get the id of the layout file.
* @return
*/
protected int getLayoutId() {
return R.layout.activity_main;
}
@Override
protected boolean isRouteDisplayed() {
return false;
}
/**
* Utility method for getting the text of an EditText, if no text was entered the hint is returned
* @param editText
* @return
*/
public String getText(EditText editText){
String s = editText.getText().toString();
if("".equals(s)) s=editText.getHint().toString();
return s;
}
/**
* Hides the softkeyboard
* @param v
*/
public void hideSoftKeyboard(View v){
//hides soft keyboard
final InputMethodManager imm = (InputMethodManager)getSystemService(
Context.INPUT_METHOD_SERVICE);
imm.hideSoftInputFromWindow(v.getWindowToken(), 0);
}
}
谢谢