java - 如何计算最近的餐厅，但我的代码显示了附近的所有餐厅

Question

我的代码正在搜索附近的餐馆，并且通过在 map 上显示所有最近的餐馆来正常工作，但我想要非常靠近餐厅，我只想在 TextView 中显示 1 家餐厅，我不知道如何计算最短路径。请帮忙，谢谢:)

import android.Manifest;
import android.content.pm.PackageManager;
import android.location.Location;
import android.os.Build;
import android.support.v4.app.ActivityCompat;
import android.support.v4.app.FragmentActivity;
import android.os.Bundle;
import android.support.v4.content.ContextCompat;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GoogleApiAvailability;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.location.LocationListener;
import com.google.android.gms.location.LocationRequest;
import com.google.android.gms.location.LocationServices;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.BitmapDescriptorFactory;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.Marker;
import com.google.android.gms.maps.model.MarkerOptions;

import java.util.HashMap;
import java.util.List;

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback,
        GoogleApiClient.ConnectionCallbacks,
        GoogleApiClient.OnConnectionFailedListener,
        LocationListener {

    private GoogleMap mMap;
    double latitude;
    double longitude;
    private int PROXIMITY_RADIUS = 10000;
    GoogleApiClient mGoogleApiClient;
    Location mLastLocation;
    Marker mCurrLocationMarker;
    LocationRequest mLocationRequest;

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

    if (android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
        checkLocationPermission();
    }

    //Check if Google Play Services Available or not
    if (!CheckGooglePlayServices()) {
        Log.d("onCreate", "Finishing test case since Google Play Services are not available");
        finish();
    }
    else {
        Log.d("onCreate","Google Play Services available.");
    }

    // Obtain the SupportMapFragment and get notified when the map is ready to be used.
    SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
            .findFragmentById(R.id.map);
    mapFragment.getMapAsync(this);
}

private boolean CheckGooglePlayServices() {
    GoogleApiAvailability googleAPI = GoogleApiAvailability.getInstance();
    int result = googleAPI.isGooglePlayServicesAvailable(this);
    if(result != ConnectionResult.SUCCESS) {
        if(googleAPI.isUserResolvableError(result)) {
            googleAPI.getErrorDialog(this, result,
                    0).show();
        }
        return false;
    }
    return true;
}


/**
 * Manipulates the map once available.
 * This callback is triggered when the map is ready to be used.
 * This is where we can add markers or lines, add listeners or move the camera. In this case,
 * we just add a marker near Sydney, Australia.
 * If Google Play services is not installed on the device, the user will be prompted to install
 * it inside the SupportMapFragment. This method will only be triggered once the user has
 * installed Google Play services and returned to the app.
 */
@Override
public void onMapReady(GoogleMap googleMap) {
    mMap = googleMap;
    mMap.setMapType(GoogleMap.MAP_TYPE_HYBRID);

    //Initialize Google Play Services
    if (android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
        if (ContextCompat.checkSelfPermission(this,
                Manifest.permission.ACCESS_FINE_LOCATION)
                == PackageManager.PERMISSION_GRANTED) {
            buildGoogleApiClient();
            mMap.setMyLocationEnabled(true);
        }
    }
    else {
        buildGoogleApiClient();
        mMap.setMyLocationEnabled(true);
    }

    Button btnRestaurant = (Button) findViewById(R.id.btnRestaurant);
    btnRestaurant.setOnClickListener(new View.OnClickListener() {
        String Restaurant = "restaurant";
        @Override
        public void onClick(View v) {
            Log.d("onClick", "Button is Clicked");
            mMap.clear();
            String url = getUrl(latitude, longitude, Restaurant);
            Object[] DataTransfer = new Object[2];
            DataTransfer[0] = mMap;
            DataTransfer[1] = url;
            Log.d("onClick", url);
            GetNearbyPlacesData getNearbyPlacesData = new GetNearbyPlacesData();
            getNearbyPlacesData.execute(DataTransfer);
            Toast.makeText(MapsActivity.this,"Nearby Restaurants", Toast.LENGTH_LONG).show();
        }
    });




}

protected synchronized void buildGoogleApiClient() {
    mGoogleApiClient = new GoogleApiClient.Builder(this)
            .addConnectionCallbacks(this)
            .addOnConnectionFailedListener(this)
            .addApi(LocationServices.API)
            .build();
    mGoogleApiClient.connect();
}

@Override
public void onConnected(Bundle bundle) {
    mLocationRequest = new LocationRequest();
    mLocationRequest.setInterval(1000);
    mLocationRequest.setFastestInterval(1000);
    mLocationRequest.setPriority(LocationRequest.PRIORITY_BALANCED_POWER_ACCURACY);
    if (ContextCompat.checkSelfPermission(this,
            Manifest.permission.ACCESS_FINE_LOCATION)
            == PackageManager.PERMISSION_GRANTED) {
        LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, this);
    }
}

private String getUrl(double latitude, double longitude, String nearbyPlace) {

    StringBuilder googlePlacesUrl = new StringBuilder("https://maps.googleapis.com/maps/api/place/nearbysearch/json?");
    googlePlacesUrl.append("location=" + latitude + "," + longitude);
    googlePlacesUrl.append("&radius=" + PROXIMITY_RADIUS);
    googlePlacesUrl.append("&type=" + nearbyPlace);
    googlePlacesUrl.append("&sensor=true");
    googlePlacesUrl.append("&key=" + "AIzaSyATuUiZUkEc_UgHuqsBJa1oqaODI-3mLs0");
    Log.d("getUrl", googlePlacesUrl.toString());
    return (googlePlacesUrl.toString());
}

@Override
public void onConnectionSuspended(int i) {

}

@Override
public void onLocationChanged(Location location) {
    Log.d("onLocationChanged", "entered");

    mLastLocation = location;
    if (mCurrLocationMarker != null) {
        mCurrLocationMarker.remove();
    }

    //Place current location marker
    latitude = location.getLatitude();
    longitude = location.getLongitude();
    LatLng latLng = new LatLng(location.getLatitude(), location.getLongitude());
    MarkerOptions markerOptions = new MarkerOptions();
    markerOptions.position(latLng);
    markerOptions.title("Current Position");
    markerOptions.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_MAGENTA));
    mCurrLocationMarker = mMap.addMarker(markerOptions);

    //move map camera
    mMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));
    mMap.animateCamera(CameraUpdateFactory.zoomTo(11));
    Toast.makeText(MapsActivity.this,"Your Current Location", Toast.LENGTH_LONG).show();

    Log.d("onLocationChanged", String.format("latitude:%.3f longitude:%.3f",latitude,longitude));

    //stop location updates
    if (mGoogleApiClient != null) {
        LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, this);
        Log.d("onLocationChanged", "Removing Location Updates");
    }
    Log.d("onLocationChanged", "Exit");

}

@Override
public void onConnectionFailed(ConnectionResult connectionResult) {

}

public static final int MY_PERMISSIONS_REQUEST_LOCATION = 99;
public boolean checkLocationPermission(){
    if (ContextCompat.checkSelfPermission(this,
            Manifest.permission.ACCESS_FINE_LOCATION)
            != PackageManager.PERMISSION_GRANTED) {

        // Asking user if explanation is needed
        if (ActivityCompat.shouldShowRequestPermissionRationale(this,
                Manifest.permission.ACCESS_FINE_LOCATION)) {

            // Show an explanation to the user *asynchronously* -- don't block
            // this thread waiting for the user's response! After the user
            // sees the explanation, try again to request the permission.

            //Prompt the user once explanation has been shown
            ActivityCompat.requestPermissions(this,
                    new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
                    MY_PERMISSIONS_REQUEST_LOCATION);


        } else {
            // No explanation needed, we can request the permission.
            ActivityCompat.requestPermissions(this,
                    new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
                    MY_PERMISSIONS_REQUEST_LOCATION);
        }
        return false;
    } else {
        return true;
    }
}

@Override
public void onRequestPermissionsResult(int requestCode,
                                       String permissions[], int[] grantResults) {
    switch (requestCode) {
        case MY_PERMISSIONS_REQUEST_LOCATION: {
            // If request is cancelled, the result arrays are empty.
            if (grantResults.length > 0
                    && grantResults[0] == PackageManager.PERMISSION_GRANTED) {

                // permission was granted. Do the
                // contacts-related task you need to do.
                if (ContextCompat.checkSelfPermission(this,
                        Manifest.permission.ACCESS_FINE_LOCATION)
                        == PackageManager.PERMISSION_GRANTED) {

                    if (mGoogleApiClient == null) {
                        buildGoogleApiClient();
                    }
                    mMap.setMyLocationEnabled(true);
                }

            } else {

                // Permission denied, Disable the functionality that depends on this permission.
                Toast.makeText(this, "permission denied", Toast.LENGTH_LONG).show();
            }
            return;
        }

        // other 'case' lines to check for other permissions this app might request.
        // You can add here other case statements according to your requirement.
    }
}

}

Answer 1

用于查找最接近的项目的伪代码:

closest = none;
for each item in items
{
  if(!closest || item.distance > closest.distance)
  {
    closest = item
  }
}
print "Closest Item is: " closest