我正在尝试通过按下按钮在文本视图中显示android设备的位置。该程序启动，但是仅当已经从另一个程序（例如，从Google地图）确定了位置时，才搜索位置。 locationManager.getLastKnownLocation有问题吗？那么如何解决这种情况呢？不需要永久放置位置跟踪。
MainActivity.java：
import android.content.pm.PackageManager;
import android.location.Location;
import android.location.LocationManager;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.Manifest;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.provider.Settings;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
private static final int REQUEST_LOCATION = 1;
Button button;
TextView textView;
LocationManager locationManager;
String lattitude,longitude;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ActivityCompat.requestPermissions(this, new String[]{android.Manifest.permission.ACCESS_FINE_LOCATION}, REQUEST_LOCATION);
textView = findViewById(R.id.text_location);
button = findViewById(R.id.button_location);
button.setOnClickListener(this);
}
@Override
public void onClick(View view) {
locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
if (!locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER)) {
buildAlertMessageNoGps();
} else if (locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER)) {
getLocation();
}
}
private void getLocation() {
if (ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.ACCESS_FINE_LOCATION)
!= PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission
(MainActivity.this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, REQUEST_LOCATION);
} else {
Location location = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
Location location1 = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
Location location2 = locationManager.getLastKnownLocation(LocationManager. PASSIVE_PROVIDER);
if (location != null) {
double latti = location.getLatitude();
double longi = location.getLongitude();
lattitude = String.valueOf(latti);
longitude = String.valueOf(longi);
textView.setText("Current coordinates"+ "\n" + "Latitude = " + lattitude
+ "\n" + "Longitude = " + longitude);
} else if (location1 != null) {
double latti = location1.getLatitude();
double longi = location1.getLongitude();
lattitude = String.valueOf(latti);
longitude = String.valueOf(longi);
textView.setText("Current coordinates"+ "\n" + "Latitude = " + lattitude
+ "\n" + "Longitude = " + longitude);
} else if (location2 != null) {
double latti = location2.getLatitude();
double longi = location2.getLongitude();
lattitude = String.valueOf(latti);
longitude = String.valueOf(longi);
textView.setText("Current coordinates"+ "\n" + "Latitude = " + lattitude
+ "\n" + "Longitude = " + longitude);
}else{
Toast.makeText(this,"Unble to Trace your location",Toast.LENGTH_SHORT).show();
}
}
}
protected void buildAlertMessageNoGps() {
final AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setMessage("Please Turn ON your GPS Connection")
.setCancelable(false)
.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
public void onClick(final DialogInterface dialog, final int id) {
startActivity(new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS));
}
})
.setNegativeButton("No", new DialogInterface.OnClickListener() {
public void onClick(final DialogInterface dialog, final int id) {
dialog.cancel();
}
});
final AlertDialog alert = builder.create();
alert.show();
}
}
activity_main.xml：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<Button
android:id="@+id/button_location"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="146dp"
android:text="Местоположение" />
<TextView
android:id="@+id/text_location"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:textSize="16sp"/>
</RelativeLayout>
AndroidManifest.xml
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
源代码：here