如何使android应用程序显示具有多个标记的最近地点

Question

我正在尝试制作一个应用程序，它显示离我当前位置最近的 5 个带有多个标记的位置。在其他主题上，我看到了许多示例，但是没有人解释如何使用多个标记或 HashMap 创建显示最近位置的应用程序。请帮我解决。

这是我的主要活动.java

public class MainActivity extends Activity
{
    private GoogleMap mMap;
    private ArrayList<MyMarker> mMyMarkersArray = new ArrayList<MyMarker>();
    private HashMap<Marker, MyMarker> mMarkersHashMap;

@Override
protected void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mMarkersHashMap = new HashMap<Marker, MyMarker>();

mMyMarkersArray.add(new MyMarker("Restaurant Zaplet", "Telephone:   \n Address: ", "iconZaplet", Double.parseDouble("43.381499"), Double.parseDouble("19.808931")));
mMyMarkersArray.add(new MyMarker("Restaurant Oresac", "Telephone:   \n Address: ","iconOresac", Double.parseDouble("43.796009"), Double.parseDouble("21.745934")));
mMyMarkersArray.add(new MyMarker("Restaurant Obilic","Telephone:  \n    Address: ", "iconObilic", Double.parseDouble("42.547670"), Double.parseDouble("19.660000")));
mMyMarkersArray.add(new MyMarker("Restaurant Dva sesira","Telephone:    \n Address: XII vek", "iconDvaSesira", Double.parseDouble("41.486736"), Double.parseDouble("20.731670")));
mMyMarkersArray.add(new MyMarker("Manastir Lipov Lad", "Telephone:  \n Address: ","iconLipovLad", Double.parseDouble("44.850546"), Double.parseDouble("20.479869")));
mMyMarkersArray.add(new MyMarker("Restaurant Slodes", "Telephone: nepoznato \n Address: ", "iconSlodes", Double.parseDouble("41.503238"), Double.parseDouble("19.791890")));

    setUpMap();

    plotMarkers(mMyMarkersArray);

}

private void plotMarkers(ArrayList<MyMarker> markers)
{
    if(markers.size() > 0)
    {
        for (MyMarker myMarker : markers)
        {

            MarkerOptions markerOption = new MarkerOptions().position(new LatLng(myMarker.getmLatitude(), myMarker.getmLongitude()));
            markerOption.icon(BitmapDescriptorFactory.fromResource(R.drawable.ic_restaurant));

            Marker currentMarker = mMap.addMarker(markerOption);
            mMarkersHashMap.put(currentMarker, myMarker);

            mMap.setInfoWindowAdapter(new MarkerInfoWindowAdapter());

        }
    }
}

private int manageMarkerIcon(String markerIcon)
{
    if (markerIcon.equals("iconZaplet"))
        return R.drawable.zaplet;
    else if(markerIcon.equals("iconOresac"))
        return R.drawable.oresac;
    else if(markerIcon.equals("iconObilic"))
        return R.drawable.obilic;
    else if(markerIcon.equals("iconLipovLad"))
        return R.drawable.lipovlad;
    else if(markerIcon.equals("iconSlodes"))
        return R.drawable.slodes;
    else
        return R.drawable.icondefault;
}


private void setUpMap()
{
    if (mMap == null)
    {
        mMap = ((MapFragment) getFragmentManager().findFragmentById(R.id.map)).getMap();


        if (mMap != null)
        {
            mMap.setMyLocationEnabled(true);

            LocationManager lm = (LocationManager) getSystemService (LOCATION_SERVICE);

            String provider = lm.getBestProvider(new Criteria (), true);

            if (provider == null) {
                onProviderDisabled (provider);
            }

            Location loc = lm.getLastKnownLocation(provider);
            if (loc != null) {
                onLocationChanged (loc);
            }


            mMap.setOnMapLongClickListener(onLongClickMapSettings ());
            mMap.setOnMarkerClickListener(new GoogleMap.OnMarkerClickListener()
            {
                @Override
                public boolean onMarkerClick(com.google.android.gms.maps.model.Marker marker)
                {
                    marker.showInfoWindow();
                    return true;
                }
            });
        }
        else
            Toast.makeText(getApplicationContext(), "Unable to create Maps", Toast.LENGTH_SHORT).show();
    }
}

private OnMapLongClickListener onLongClickMapSettings() {
    // TODO Auto-generated method stub
    return new OnMapLongClickListener () {

        @Override
        public void onMapLongClick(LatLng arg0) {
            // TODO Auto-generated method stub
            Log.i(arg0.toString(), "User long clicked");

        }

    };
}

public void onLocationChanged(Location location) {
    // TODO Auto-generated method stub

    LatLng latlng = new LatLng (location.getLatitude(), location.getLongitude());

    mMap.moveCamera(CameraUpdateFactory.newLatLng(latlng));
    mMap.animateCamera(CameraUpdateFactory.zoomTo(10));

}


public void onStatusChanged(String provider, int status, Bundle extras) {
    // TODO Auto-generated method stub

}


public void onProviderEnabled(String provider) {
    // TODO Auto-generated method stub

}


public void onProviderDisabled(String provider) {
    // TODO Auto-generated method stub

}

public class MarkerInfoWindowAdapter implements GoogleMap.InfoWindowAdapter
{
    public MarkerInfoWindowAdapter()
    {
    }

    @Override
    public View getInfoWindow(Marker marker)
    {
        return null;
    }


    @SuppressLint("InflateParams") @Override
    public View getInfoContents(Marker marker)
    {
        View v  = getLayoutInflater().inflate(R.layout.info_window_layout, null);

        MyMarker myMarker = mMarkersHashMap.get(marker);

        ImageView markerIcon = (ImageView) v.findViewById(R.id.marker_icon);

        TextView markerLabel = (TextView)v.findViewById(R.id.marker_label);

        TextView anotherLabel = (TextView)v.findViewById(R.id.another_label);

        markerIcon.setImageResource(manageMarkerIcon(myMarker.getmIcon()));

        markerLabel.setText(myMarker.getmLabel());
        anotherLabel.setText(myMarker.getmIstorijat());

        return v;
    }
}

}

这是 MyMarker.java 的代码

> public class MyMarker
{
    private String mLabel;
    private String mIstorijat;
    private String mIcon;
    private Double mLatitude;
    private Double mLongitude;

public MyMarker(String label, String istorijat, String icon, Double latitude, Double longitude)
{
    this.mLabel = label;
    this.mIstorijat = istorijat;
    this.mLatitude = latitude;
    this.mLongitude = longitude;
    this.mIcon = icon;
}

public String getmLabel()
{
    return mLabel;
}

public void setmLabel(String mLabel)
{
    this.mLabel = mLabel;
}

public String getmIstorijat()
{
    return mIstorijat;
}

public void setmIstorijat(String mIstorijat)
{
    this.mIstorijat = mIstorijat;
}

public String getmIcon()
{
    return mIcon;
}

public void setmIcon(String icon)
{
    this.mIcon = icon;
}

public Double getmLatitude()
{
    return mLatitude;
}

public void setmLatitude(Double mLatitude)
{
    this.mLatitude = mLatitude;
}

public Double getmLongitude()
{
    return mLongitude;
}

public void setmLongitude(Double mLongitude)
{
    this.mLongitude = mLongitude;
}

}

Answer 1

很抱歉，我不太了解您的问题。您似乎知道如何使用 HashMap 使用 MyMarker 对象恢复地图标记。您还可以创建您需要的所有标记。由于您的问题是关于使用 HashMap 和多个标记创建应用程序，因此您似乎已经这样做了。除非您的代码不起作用，但在这种情况下，如果您告诉我们它的确切作用会有所帮助。

我不确定你在问什么，但我相信你有 5 个标记，并且你想得到最接近的一个。如果您的问题是如何做到这一点，那么我认为您只需要循环每个标记并计算它们与用户位置的距离即可找到最小的。

如果你不知道如何计算距离，我个人使用 Location 的 distanceTo(Location) 方法。也许它不是最好的代码，但它看起来是这样的：

public static double distanceTo(LatLng from, LatLng to) {
    Location locationA = new Location("");
    locationA.setLatitude(from.latitude);
    locationA.setLongitude(from.longitude);
    Location locationB = new Location("");
    locationB.setLatitude(to.latitude);
    locationB.setLongitude(to.longitude);
    return locationA.distanceTo(locationB) / 1000;
}

你可以做类似的事情：

Marker closest = null;
double minDistance;
for(Marker m : mMarkersHashMap.keySet()){
    double distance = distanceTo(currentPos, m.getPosition())
    if(closest == null || minDistance > distance){
        closest = m;
        minDistance = distance;
    }
}

写得很快，还没有测试过，但如果你想为最接近的 5 个标记做它，我认为这是可行的：

Marker[] closest = new Marker[5];
double[] minDistance = new double[5];
for(Marker m : mMarkersHashMap.keySet()){
    double distance = distanceTo(currentPos, m.getPosition())
    for(int i = 4; i >=0; i--){
        if(closest[i] == null || minDistance[i] > distance){
            if(i < 4){
                closest[i+1] = closest[i];
                minDistance[i+1] = minDistance[i];
            }
            closest[i] = m;
            minDistance[i] = distance;
        } else {
            break;
        }
    }
}