API 23及之后版本关于用android studio 中LocationManager的方法使用

package com.example.administrator.locationtest;

import android.app.Activity;
import android.content.Context;
import android.content.pm.PackageManager;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.support.v4.content.ContextCompat;
import android.widget.TextView;
import android.widget.Toast;

import org.w3c.dom.Text;

import java.util.List;
import java.util.jar.Manifest;

/**
 * Created by Administrator on 2016/4/8.
 */
public class MainActivity extends Activity{
    private TextView positionTextView;
    private LocationManager locationManager;
    private String provider;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        positionTextView=(TextView)findViewById(R.id.position_text_view);
        locationManager=(LocationManager)getSystemService(Context.LOCATION_SERVICE);
        if(ContextCompat.checkSelfPermission(this,android.Manifest.permission.ACCESS_FINE_LOCATION)== PackageManager.PERMISSION_GRANTED){

//此处的判定是主要问题，API23之后需要先判断之后才能调用locationManager中的方法

//包括这里的getLastKnewnLocation方法和requestLocationUpdates方法
            Location location=locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
            if(location!=null){
                showLocation(location);
            }
            locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER,5000,10,locationListener);
        }
    }
    @Override
    protected void onDestroy() {
        super.onDestroy();
        if(ContextCompat.checkSelfPermission(this,android.Manifest.permission.ACCESS_FINE_LOCATION)== PackageManager.PERMISSION_GRANTED){

//此处同样需要判定之后才能调用removeUpdates方法
            if(locationManager!=null){
                locationManager.removeUpdates(locationListener);
            }
        }
    }
    LocationListener locationListener=new LocationListener() {
        @Override
        public void onLocationChanged(Location location) {
            showLocation(location);
        }

        @Override
        public void onStatusChanged(String provider, int status, Bundle extras) {

        }

        @Override
        public void onProviderEnabled(String provider) {

        }

        @Override
        public void onProviderDisabled(String provider) {

        }
    };
    private void showLocation(Location location){
        String currentPosition="latitude is"+location.getLatitude()+"\n"+"longitude is"+location.getLongitude();
        positionTextView.setText(currentPosition);
    }
}