如何跟踪用户跑步/行走时的距离

Question

我正在做一个可以跟踪跑步距离的应用程序。 我的想法是当我点击开始时，我将记录我开始运行的位置，然后当我点击停止时，它将记录我结束运行的位置。然后计算这2点之间的距离。 我不知道为什么我的距离结果不管我怎么跑我都会向我显示0km。请帮我看看是否有任何问题〜

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package com.example.ifitness;

import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.GoogleMap.OnMapLongClickListener;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.SupportMapFragment;

import android.content.Intent;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.os.Handler;
import android.os.SystemClock;
import android.support.v7.app.ActionBarActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

＆＃13;

public class calorieburn extends ActionBarActivity implements LocationListener{
private GoogleMap map;
private Location startLocation;
private Location endLocation;
private double latA;
private double longA;
private double latB;
private double longB;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.calorieburn);
        SetupMap();           
        
        Button start = (Button) findViewById(R.id.start);
        
        start.setOnClickListener(new View.OnClickListener() {
			
			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
				
				  latA = startLocation.getLatitude();
				  longA = startLocation.getLongitude();
				  
				  TextView distance = (TextView) findViewById(R.id.distance);
				  distance.setText("0 km");
				  
				  TextView calorie = (TextView) findViewById(R.id.calorie);
				  calorie.setText("0 cal");
				  
				  
			}
		});
        
        Button stop = (Button) findViewById(R.id.stop);
        
        stop.setOnClickListener(new View.OnClickListener() {
			
			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
				  
				  latB = endLocation.getLatitude();
				  longB = endLocation.getLongitude();
			
				  TextView distance = (TextView) findViewById(R.id.distance);
				  distance.setText(String.valueOf(distance(latA,longA,latB,longB)+ "km"));
				  
				  TextView calorie = (TextView) findViewById(R.id.calorie);
				  calorie.setText(String.valueOf(distance(latA,longA,latB,longB)+ "cal"));
			}
		});            
              
 }

    public double calories(double distance){
    	
    	double calories = 0;
    	calories = distance * 100;
    	return calories;
    }

    public static void distanceBetween(){
    	
    }
    
    public double distance(double lat,double lng,double latitude,double longtitude){
    	Location locA = new Location("locA");
		locA.setLatitude(lat);
		locA.setLongitude(lng);
		
		Location locB = new Location("locB");
		locB.setLatitude(latitude);
		locB.setLongitude(longtitude);
		
		double distance = locA.distanceTo(locB);
		
		return distance;
	
    }
    
	private void SetupMap() {
		if (map == null){
	     // Getting reference to the SupportMapFragment of activity_main.xml	
   		 SupportMapFragment mf = (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map);
   	    
   		 // get google map from the fragment
   		 map = mf.getMap();   	                  	        
   		}
   	
   	if (map !=null ){
   	
   		// Enabling MyLocation Layer of Google Map
   		map.setMyLocationEnabled(true);
   		
   		// Getting LocationManager object from System Service LOCATION_SERVICE
   		LocationManager lm = (LocationManager) getSystemService(LOCATION_SERVICE);
   		Criteria criteria = new Criteria();
   		criteria.setAccuracy(Criteria.ACCURACY_FINE);
   		String bestprovider = lm.getBestProvider(criteria,false);
   		String provider = LocationManager.NETWORK_PROVIDER;
   		
   		if (provider == null){
   			onProviderDisabled(provider);
   		}
   		
   		// Getting Current Location
   		Location loc = lm.getLastKnownLocation(bestprovider);
   		if (loc != null){
   			onLocationChanged(loc);
   			
   		}
   		
   		map.setOnMapLongClickListener(onLongClickMapSettings());
   	}
  }

	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");
			}
		};			
	}
	
	@Override
	public void onLocationChanged(Location location) {
		// TODO Auto-generated method stub

		// Getting latitude of the current location
        double latitude = location.getLatitude();
 
        // Getting longitude of the current location
        double longitude = location.getLongitude();
 
        // Creating a LatLng object for the current location
        LatLng latLng = new LatLng(latitude, longitude);
 
        // Showing the current location in Google Map
        map.moveCamera(CameraUpdateFactory.newLatLng(latLng));
 
        // Zoom in the Google Map
        map.animateCamera(CameraUpdateFactory.zoomTo(17));
		
	}

	private void makeUseOfNewLocation(Location location) {
		// TODO Auto-generated method stub
		
	}

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

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

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

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