当我按“获取位置”按钮时，我的应用程序崩溃

Question

当我按“获取位置”按钮时，无论如何我都从这里复制了代码以从此处获取应用中的坐标http://rdcworld-android.blogspot.hr/2012/01/get-current-location-coordinates-city.html然后退出。

MainActivity.java

package com.lipa.flashlight;

import android.*;
import android.app.AlertDialog;
import android.content.ContentResolver;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.location.Address;
import android.location.Geocoder;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.ParcelFileDescriptor;
import android.provider.Settings;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ProgressBar;
import android.widget.Toast;
import android.view.View.OnClickListener;

import java.io.IOException;
import java.util.List;
import java.util.Locale;

public class Main2Activity extends AppCompatActivity implements OnClickListener {    

    private LocationManager locationManager = null;
    private LocationListener locationListener = null;

    private Button location = null;
    private EditText editLocation = null;
    private ProgressBar pb =null;

    private static final String TAG = "Debug";
    private Boolean flag = false;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);

        pb = (ProgressBar) findViewById(R.id.progressBar1);
        pb.setVisibility(View.INVISIBLE);

        editLocation = (EditText) findViewById(R.id.editTextLocation);
        location = (Button) findViewById(R.id.location);
        location.setOnClickListener(this);
    }    

    @Override
    public void onClick(View v) {
        flag = displayGpsStatus();
        if (flag) {
            Log.v(TAG, "onClick");
            editLocation.setText("Please! move your device to" +
                    " see the changes in coordinates." + "\nWait...");

            pb.setVisibility(View.VISIBLE);
            locationListener = new MyLocationListener();

            if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED &&
                    ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_COARSE_LOCATION)
                            != PackageManager.PERMISSION_GRANTED) {    
                return;
            }
            locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 5000, 10, locationListener);

        } else {
            alertbox("GPS STATUS!!", "Your GPS is: OFF");
        }
    }

    private Boolean displayGpsStatus(){
        ContentResolver contentResolver = getBaseContext().getContentResolver();
        boolean gpsStatus = Settings.Secure.isLocationProviderEnabled(contentResolver, LocationManager.GPS_PROVIDER);
        if(gpsStatus){
            return true;

        }else{
            return false;
        }    
    }

    protected void alertbox(String title, String mymessage){
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setMessage("Your Device's GPS is disabled")
                .setCancelable(false)
                .setTitle("** Gps Status **")
                .setPositiveButton("Gps On", new DialogInterface.OnClickListener(){
                    public void onClick(DialogInterface dialog, int id) {
                        Intent myIntent = new Intent(
                                Settings.ACTION_SECURITY_SETTINGS);
                        startActivity(myIntent);
                        dialog.cancel();
                    }
                })
                .setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int id){
                        dialog.cancel();
                    }
                });
        AlertDialog alert = builder.create();
        alert.show();
    }

    private class MyLocationListener implements LocationListener {
        @Override
        public void onLocationChanged(Location loc){    

            editLocation.setText("");
            pb.setVisibility(View.INVISIBLE);
            Toast.makeText(getBaseContext(),"Location changed: Lat: "+
                    loc.getLatitude()+" Lng: " + loc.getLongitude(), Toast.LENGTH_SHORT).show();
            String longitude = "Longitude: " +loc.getLongitude();
            Log.v(TAG, longitude);
            String latitude = "Latitude: " +loc.getLatitude();
            Log.v(TAG, latitude);

            String cityName=null;
            Geocoder gcd = new Geocoder(getBaseContext(),
                    Locale.getDefault());
            List<Address> addresses;
            try {
                addresses = gcd.getFromLocation(loc.getLatitude(), loc
                        .getLongitude(), 1);
                if (addresses.size() > 0)
                    System.out.println(addresses.get(0).getLocality());
                cityName=addresses.get(0).getLocality();
            } catch (IOException e) {
                e.printStackTrace();
            }

            String s = longitude+"\n"+latitude +
                    "\n\nMy Currrent City is: "+cityName;
            editLocation.setText(s);    
        }

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

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

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

XML：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:weightSum="1">
<TextView
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="Get Current Location and City Name"
    android:layout_weight="0.20"
    android:gravity="center"
    android:textSize="20sp" />
<EditText
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_weight="0.33"
    android:id="@+id/editTextLocation"
    android:editable="false">
    <requestFocus></requestFocus>
</EditText>
<LinearLayout
    android:id="@+id/layButtonH"
    android:layout_height="wrap_content"
    android:layout_width="fill_parent"
    android:gravity="center"
    android:layout_weight="0.15">
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Get Location"
        android:id="@+id/location"></Button>
</LinearLayout>
<LinearLayout
    android:id="@+id/layloadingH"
    android:layout_height="wrap_content"
    android:layout_weight="0.20"
    android:layout_width="fill_parent"
    android:gravity="center">
    <ProgressBar
        android:layout_width="wrap_content"
        android:id="@+id/progressBar1"
        android:layout_height="wrap_content"></ProgressBar>
</LinearLayout>
</LinearLayout>

Answer 1

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

    return;
}

该应用程序是否具有权限？ 否则，您的代码中将不会到达requestLocationUpdates。

locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 5000, 10, locationListener);

minDistance参数还可以用于控制位置更新的频率。 如果大于0，则位置提供者仅在位置更改了至少minDistance米，并且至少经过了minTime毫秒时，才向您的应用程序发送更新

at least minDistance meters, AND at least minTime milliseconds have passed考虑这部分at least minDistance meters, AND at least minTime milliseconds have passed位置管理器文档中 at least minDistance meters, AND at least minTime milliseconds have passed