java - 如何在android中的onMapReady()中获取onNavigationItemSelected()值

Question

我试图为抽屉导航中列出的每个项目提供位置坐标，并将其指向谷歌地图。

它如何获取我分配给 onNavigationItemSelected() 到 onMapReady() 中的变量的纬度和经度？

//This is were I assign the coordiantes
@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
    // Handle navigation view item clicks here.
    int id = item.getItemId();

    double lat = 0;
    double lon = 0;

    if (id == R.id.redBuilding){
        /*lat = 13.010982;
        lon = 80.235444;

        String latitude = Double.toString(lat);
        String longitude = Double.toString(lon);
        latLong = latitude+"/"+longitude; */
    }

    if (id == R.id.nav_share) {
    } else if (id == R.id.nav_send) {
    }

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    drawer.closeDrawer(GravityCompat.START);
    return true;
}

我想在此方法中获取分配的坐标以将其指向 map 上:

@Override
public void onMapReady(GoogleMap googleMap) {
    mMap = googleMap;
LatLng latLon = new LatLng(13.0827, 80.2707);
    mMap.addMarker(new MarkerOptions().position(latLon).title("Marker is in Chennai.").snippet("India"));
    mMap.moveCamera(CameraUpdateFactory.newLatLng(latLon));
}

我只使用一个 Activity，其中 map 位于 Fragment 中。

Answer 1

如果您想更改标记，则不必使用onMapReady。您可以在初始化 map 时保存标记，然后在每次用户选择项目时更改它。

private Marker marker;

@Override
public void onMapReady(GoogleMap googleMap) {
    mMap = googleMap;
    LatLng latLon = new LatLng(13.0827, 80.2707);
    marker = mMap.addMarker(new MarkerOptions().position(latLon).title("Marker is in Chennai.").snippet("India"));
    mMap.moveCamera(CameraUpdateFactory.newLatLng(latLon));
}

@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
    // Handle navigation view item clicks here.
    int id = item.getItemId();

    double lat = 0;
    double lon = 0;

    if (id == R.id.redBuilding){
        lat = 13.010982;
        lon = 80.235444;

        mMap.moveCamera(CameraUpdateFactory.newLatLng(new LatLng(lat, lon));
        marker.setPosition(new LatLng(lat, lon));
        marker.setTitle("your new title");
    }

    if (id == R.id.nav_share) {
    } else if (id == R.id.nav_send) {
    }

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    drawer.closeDrawer(GravityCompat.START);
    return true;
}