我正在尝试实现位置警报类应用程序。 但每当我的应用程序打开我当前的位置显示为null。
以下是我的代码。
package com.hrupin;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.AlertDialog.Builder;
import android.content.Context;
import android.content.DialogInterface;
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.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
public class HelloAndroidGpsActivity extends Activity implements OnClickListener, android.content.DialogInterface.OnClickListener, LocationListener {
private TextView setLat, setLong, destLat, destLong, currLat, currLong, tjd, fromhome, toward;
private Button setmyLoc, setDest;
private EditText editLat, editLong;
private LocationManager orgManager;
//private LocationListener orgListener;
// private LocationListener destListener = new destListener();
private boolean gps_enabled = false;
private boolean network_enabled = false;
private String bestProvider;
double orginLongitude, orginLatitude, destLongtitude, destLatitude, currLatitude, currLongtitude;
float firstLat, firstLang, secLat, secLang;
Location destinationLocation = new Location("gps");
Location originLocation = new Location("gps");
Location currLocation = new Location("gps");
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
setLat = (TextView) findViewById(R.id.setLat);
setLong = (TextView) findViewById(R.id.setLong);
destLat = (TextView) findViewById(R.id.destLat);
destLong = (TextView) findViewById(R.id.destLong);
currLat = (TextView) findViewById(R.id.currLat);
currLong = (TextView)findViewById(R.id.currLong);
tjd = (TextView)findViewById(R.id.setmeter);
fromhome = (TextView)findViewById(R.id.destmeter);
toward = (TextView)findViewById(R.id.currmeter);
setDest = (Button)findViewById(R.id.SetLocation);
editLat = (EditText)findViewById(R.id.editLat);
editLong = (EditText)findViewById(R.id.editLong);
orgManager = (LocationManager)this.getSystemService(Context.LOCATION_SERVICE);
try {
gps_enabled = orgManager
.isProviderEnabled(LocationManager.GPS_PROVIDER);
} catch (Exception ex) {
Log.i("gps_enabled", ex.toString());
}
try {
network_enabled = orgManager
.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
} catch (Exception ex) {
Log.i("network_enabled", ex.toString());
}
// don't start listeners if no provider is enabled
if (!gps_enabled && !network_enabled) {
AlertDialog.Builder builder = new Builder(
HelloAndroidGpsActivity.this);
builder.setTitle("Attention!");
builder.setMessage("Sorry, location is not determined. Please enable location providers");
builder.setPositiveButton("OK",
HelloAndroidGpsActivity.this);
builder.setNeutralButton("Cancel",
HelloAndroidGpsActivity.this);
builder.create().show();
}
Criteria criteria = new Criteria();
bestProvider = orgManager.getBestProvider(criteria, false);
orgManager.requestLocationUpdates(bestProvider, 0, 0, this);
Location location = orgManager.getLastKnownLocation(bestProvider);
if (location!=null){
setLat.setText("Latitude:" + currLatitude);
setLong.setText("Longitude:" + currLongtitude);
originLocation.setLatitude(currLatitude);
originLocation.setLongitude(currLongtitude);
}
//else Toast.makeText(getBaseContext(), "Error in GPS", Toast.LENGTH_SHORT).show();
setDest.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
destLat.setText("Lat:"+editLat.getText().toString().trim());
destLong.setText("Long"+editLong.getText().toString().trim());
destLatitude = Double.parseDouble(String.valueOf(editLat.getText().toString().trim()));
destLongtitude = Double.parseDouble(String.valueOf(editLong.getText().toString().trim()));
destinationLocation.setLatitude(destLatitude);
destinationLocation.setLongitude(destLongtitude);
float distance = originLocation.distanceTo(destinationLocation);
tjd.setText(String.valueOf(distance/1000)+ " Kms ");
}
});
}
/** Register for the updates when Activity is in foreground */
@Override
protected void onResume() {
super.onResume();
orgManager.requestLocationUpdates(bestProvider, 60000, 1, this);
}
/** Stop the updates when Activity is paused */
@Override
protected void onPause() {
super.onPause();
orgManager.removeUpdates(this);
}
public void onClick(DialogInterface dialog, int which) {
if (which == DialogInterface.BUTTON_NEUTRAL) {
setLat.setText("Sorry, location is not determined. To fix this please enable location providers");
} else if (which == DialogInterface.BUTTON_POSITIVE) {
startActivity(new Intent(
android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS));
}
}
public void onClick(View v) {
// TODO Auto-generated method stub
}
public void onLocationChanged(Location location) {
// TODO Auto-generated method stub
if (location != null) {
// This needs to stop getting the location data and save the
// battery power.
//orgManager.removeUpdates(orgListener);
currLatitude = location.getLatitude();
currLongtitude = location.getLongitude();
currLocation.setLatitude(currLatitude);
currLocation.setLongitude(currLongtitude);
currLat.setText(String.valueOf(currLatitude));
currLong.setText(String.valueOf(currLongtitude));
float fromhome = originLocation.distanceTo(currLocation);
float toward = currLocation.distanceTo(destinationLocation);
HelloAndroidGpsActivity.this.fromhome.setText(String.valueOf(fromhome/1000)+ " Kms ");
HelloAndroidGpsActivity.this.toward.setText(String.valueOf(toward/1000) + " Kms ");
if (toward/1000 <= 14 ){
Toast.makeText(getBaseContext(), "You are "+ toward/1000 + " Kms towards Destination ", Toast.LENGTH_SHORT).show();
}
}
}
public void onProviderDisabled(String provider) {
// TODO Auto-generated method stub
}
public void onProviderEnabled(String provider) {
// TODO Auto-generated method stub
}
public void onStatusChanged(String provider, int status, Bundle extras) {
// TODO Auto-generated method stub
}
}
我知道这种问题已经有百万次了。我已经尝试了所有在答案中指定的方法。但我没有任何输出。请帮忙。
答案 0 :(得分：0)
要获得当前位置，这对我来说非常好，请查看此内容。
我们的活动是这样的
public class MainActivity extends Activity implements OnClickListener, android.content.DialogInterface.OnClickListener {
/** Called when the activity is first created. */
private EditText showLocation;
private Button btnGetLocation;
private ProgressBar progress;
private LocationManager locManager;
private LocationListener locListener = new myLocationListener();
private boolean gps_enabled = false;
private boolean network_enabled = false;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
showLocation = (EditText) findViewById(R.id.txtShowLoc);
showLocation.setEnabled(false);
progress = (ProgressBar) findViewById(R.id.progressBar);
progress.setVisibility(View.GONE);
btnGetLocation = (Button) findViewById(R.id.btnGetLoc);
btnGetLocation.setOnClickListener(this);
locManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
}
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
progress.setVisibility(View.VISIBLE);
try{
gps_enabled = locManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
}
catch(Exception ex){
}
try{
network_enabled = locManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
}
catch(Exception ex){
}
if (!gps_enabled && !network_enabled) {
AlertDialog.Builder builder = new Builder(this);
builder.setTitle("Attention!");
builder.setMessage("Sorry, location is not determined. Please enable location providers");
builder.setPositiveButton("OK", this);
builder.setNeutralButton("Cancel", this);
builder.create().show();
progress.setVisibility(View.GONE);
}
if (gps_enabled) {
locManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locListener);
}
if (network_enabled) {
locManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, locListener);
}
}
private class myLocationListener implements LocationListener{
@Override
public void onLocationChanged(Location location) {
// TODO Auto-generated method stub
if(location!=null){
locManager.removeUpdates(locListener);
String Speed = "Device Speed: " +location.getSpeed();
String longitude = "Longitude: " +location.getLongitude();
String latitude = "Latitude: " +location.getLatitude();
String altitiude = "Altitiude: " + location.getAltitude();
String accuracy = "Accuracy: " + location.getAccuracy();
String time = "Time: " + location.getTime();
String cityName=null;
Geocoder gcd = new Geocoder(getBaseContext(), Locale.getDefault());
//public List<Address> addresses= gcd.getFromLocation (double latitude1, double longitude1, int maxResults)
List<Address> addresses;
try {
addresses = gcd.getFromLocation(location.getLatitude(), location.getLongitude(), 1);
if (addresses.size() > 0)
System.out.println(addresses.get(0).getLocality());
cityName=addresses.get(0).getLocality();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
showLocation.setText("City Name: "+cityName+"\n"+Speed + "\n"+longitude + "\n" + latitude + "\n" + altitiude + "\n" + accuracy + "\n" + time);
progress.setVisibility(View.GONE);
}
}
@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
}
}
@Override
public void onClick(DialogInterface dialog, int which) {
// TODO Auto-generated method stub
if(which == DialogInterface.BUTTON_NEUTRAL){
showLocation.setText("location is not getting due to location provider");
}
else if (which == DialogInterface.BUTTON_POSITIVE){
startActivity(new Intent(android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS));
}
}}
和main.xml是
<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:id="@+id/textView1" android:layout_width="match_parent" android:text="My Location is:" android:textSize="25sp" android:layout_height="wrap_content"></TextView>
<EditText android:layout_height="wrap_content" android:layout_width="match_parent" android:layout_weight="0.24" android:lines="5" android:id="@+id/txtShowLoc">
<requestFocus></requestFocus>
</EditText>
<LinearLayout android:id="@+id/linearLayout2" android:layout_height="wrap_content" android:layout_width="match_parent" android:gravity="center">
<ProgressBar android:layout_height="wrap_content" android:layout_width="wrap_content" android:id="@+id/progressBar"></ProgressBar>
</LinearLayout>
<LinearLayout android:id="@+id/linearLayout1" android:layout_width="match_parent" android:layout_height="wrap_content" android:gravity="center">
<Button android:layout_height="wrap_content" android:layout_width="wrap_content" android:text="Get Current Location" android:id="@+id/btnGetLoc"></Button>
</LinearLayout>
我的清单文件是
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="rdc.getCurrentLocaion"
android:versionCode="1"
android:versionName="1.0">
<uses-sdk android:minSdkVersion="8" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"></uses-permission>
<application android:icon="@drawable/icon" android:label="@string/app_name" android:debuggable="true">
<activity android:name=".MainActivity"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
如果你遇到麻烦，请告诉我!!
答案 1 :(得分：0)
@Ramdhan感谢您的代码。但我纠正了我的代码中的错误。
Criteria criteria = new Criteria();
bestProvider = orgManager.getBestProvider(criteria, false);
orgManager.requestLocationUpdates(bestProvider, 0, 0, this);
Location location = orgManager.getLastKnownLocation(bestProvider);
if (location!=null){
setLat.setText("Latitude:" + currLatitude);
setLong.setText("Longitude:" + currLongtitude);
originLocation.setLatitude(currLatitude);
originLocation.setLongitude(currLongtitude);
}
Cheanged code：
if (location != null) {
setLat.setText("Latitude:" + location.getLatitude());
setLong.setText("Longitude:" + location.getLongitude());
originLocation.setLatitude(location.getLatitude());
originLocation.setLongitude(location.getLongitude());
}
答案 2 :(得分：0)
您不应该在onCreate上调用requestLocationUpdates，因为它是多余的，因为您的代码将在onResume上调用它。流程是onCreate - ＆gt; onStart - ＆gt;的onResume。
答案 3 :(得分：0)
用于从OnCreate Methode请求位置更新
LocationManager locationManager=(LocationManager) this.getSystemService(Context.LOCATION_SERVICE);
LocationListener locationListener=new LocationListener() {
@Override
public void onLocationChanged(Location location) {
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
@Override
public void onProviderEnabled(String provider) {
}
@Override
public void onProviderDisabled(String provider) {
}
} if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION)!= PackageManager.PERMISSION_GRANTED){
ActivityCompat.requestPermissions(this,new String[]{Manifest.permission.ACCESS_FINE_LOCATION},1);
}