MapsApp，计算两点之间的距离，Android

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【中文标题】MapsApp，计算两点之间的距离，Android【英文标题】：MapsApp that calculates distance between 2 points, Android 【发布时间】：2016-04-28 08:38:44 【问题描述】：

我想创建一个可以计算两个位置之间距离的应用程序，第一个是 GPS 查找，第二个是我设置的。应用打不开，错误在

第 61 行：距离 = location.distanceTo(locationSede);

帮帮我！

package com.example.prova.mapapplicationprove;

import android.Manifest;
import android.app.Activity;
import android.app.Fragment;
import android.content.Context;
import android.content.pm.PackageManager;
import android.graphics.Point;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Display;
import android.view.Menu;
import android.widget.TextView;
import android.widget.Toast;

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

public class MainActivity extends AppCompatActivity implements LocationListener 

    private float distance;
    private float[] distfloat = new float[1];

    private final LatLng POINT = new LatLng(0, 0); //longitudine e latitudine
        LocationManager locationManager;
        @Override
        protected void onCreate(Bundle savedInstanceState) 
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);

            GoogleMap map = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map)).getMap();


            map.setMyLocationEnabled(true);
            LatLng sede = new LatLng(45.012447, 7.621013);
            map.moveCamera(CameraUpdateFactory.newLatLngZoom(POINT, 1));
            
            map.animateCamera(CameraUpdateFactory.zoomTo(10), 2000, null);
            map.addMarker(new MarkerOptions().position(sede).title("Soluzioni"));

            locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
            Criteria criteria = new Criteria();
            String provider = locationManager.getBestProvider(criteria, true);


            if(provider != null & !provider.equals(""))
            
                Location location = locationManager.getLastKnownLocation(locationManager.GPS_PROVIDER);
                locationManager.requestLocationUpdates(provider, 2000, 1, this);

                Location locationSede = new Location("Sede");
                locationSede.setLatitude(45.012447);
                locationSede.setLongitude(7.621013);
                distance = location.distanceTo(locationSede); //LINE NUMBER 61
//                location.distanceBetween(sede.latitude,sede.longitude,location.getLatitude(),location.getLongitude(),distfloat);


                if(location!=null)
                
                    onLocationChanged(location);
                
                else
                    Toast.makeText(getApplicationContext(),"Location not found, GPS disabled.",Toast.LENGTH_LONG ).show();
                
            
            else
            
                Toast.makeText(getApplicationContext(),"Provider is null.",Toast.LENGTH_LONG).show();
            


            if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) 


                return;
            
        
       
        @Override
        public void onLocationChanged(Location location) 

            Toast.makeText(this,"Latitude: " + location.getLatitude() + "\nLongitude: " + location.getLongitude(),Toast.LENGTH_LONG ).show();

            TextView textView2 = (TextView) findViewById(R.id.textview2);
            TextView textView3 = (TextView) findViewById(R.id.textview3);
            TextView textView4 = (TextView) findViewById(R.id.textview4);

            String distanza = String.valueOf(distance);
            //String distanza = String.valueOf(distfloat[0]);

            textView2.setText("Latitude="+location.getLatitude());
            textView3.setText("Longitude="+ location.getLongitude());

            textView4.setText("Distance="+ distanza);
        
        @Override
        public void onStatusChanged(String s, int i, Bundle bundle) 
        
        @Override
        public void onProviderEnabled(String s) 
        
        @Override
        public void onProviderDisabled(String s) 
        


<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.prova.mapapplicationprove">

    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.ACCESS_LOCATION_EXTRA_COMMANDS.google.android.providers.gsf.permission.READ_GSERVICES" />
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />    <!-- Per usare il GPS -->
    <uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES" />

    <uses-feature
        android:glEsVersion="0x00020000"
        android:required="true" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <meta-data
            android:name="com.google.android.geo.API_KEY"
            android:value="@string/google_maps_key" />

        <activity
            android:name=".MapsActivity"
            android:label="@string/title_activity_maps">
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value="com.example.prova.mapapplicationprove.MainActivity" />
        </activity>
    </application>

</manifest>

【问题讨论】：

请添加您的 logcat 以帮助我们了解问题 @SarahMaher 抱歉，logcat 是什么？ 你有解决办法吗？ @FrancescaBaka logcat 表示你的错误日志报告 @FrancescaBaka 请参阅下面的答案，您可以在距离之间获得两个位置。 【参考方案1】：

我觉得你应该放

distance = location.distanceTo(locationSede); //LINE NUMBER 61

进入方法

@Override
public void onLocationChanged(Location location)

看起来像

@Override
public void onLocationChanged(Location location) 
    if (location != null)
        Location locationSede = new Location("Sede");
        locationSede.setLatitude(45.012447);
        locationSede.setLongitude(7.621013);
        int distance = location.distanceTo(locationSede);

【讨论】：

@FrancescaBaka：你能发布 logcat 来检查一下吗？【参考方案2】：

如果你想计算两点之间的距离，那么你可以使用Location.distanceBetween( A.Latitude, A.Longitude, B.Latitude, B.Longitude, result);

查看下面的代码如何在你的代码中实现

    float[] result = new float[1];
    Location.distanceBetween(location.getLatitude(), location.getLongitude(), locationSede.getLatitude(), locationSede.getLongitude(), result);

    Log.e("TAG Result",""+result);   //Here result is your distance
    double km = result * 0.001;
    Log.e("TAG Result",""+km);   //Here distance in kilometer

在这里，当您想以公里为单位时，总距离乘以 0.001，例如 distancein_km=total_dis*001

【讨论】：

我也用这种方式证明过，但还是有错误。 你能不能把错误日志发给你或者见我here【参考方案3】：

我解决了我的问题，错误是由提供程序引起的：我使用 locationManager.allProvider();并以这种方式工作。 还是谢谢

【讨论】：

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