How to provide Runtime permission in Android 6.0 (API 23) +

// Called when the user is performing an action which requires the app to read the
    // user's contacts
    public void getPermissionToAccessLocation(View view) {
        // 1) Use the support library version ContextCompat.checkSelfPermission(...) to avoid
        // checking the build version since Context.checkSelfPermission(...) is only available
        // in Marshmallow
        // 2) Always check for permission (even if permission has already been granted)
        // since the user can revoke permissions at any time through Settings
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION)
                != PackageManager.PERMISSION_GRANTED) {

            // The permission is NOT already granted.
            // Check if the user has been asked about this permission already and denied
            // it. If so, we want to give more explanation about why the permission is needed.
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                if (shouldShowRequestPermissionRationale(
                        Manifest.permission.ACCESS_FINE_LOCATION)) {
                    // Show our own UI to explain to the user why we need to read the contacts
                    // before actually requesting the permission and showing the default UI
                }
            }

            // Fire off an async request to actually get the permission
            // This will show the standard permission request dialog UI
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                requestPermissions(new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
                        PERMISSIONS_REQUEST);
            }
        }
    }

    // Callback with the request from calling requestPermissions(...)
    @Override
    public void onRequestPermissionsResult(int requestCode,
                                           @NonNull String permissions[],
                                           @NonNull int[] grantResults) {
        // Make sure it's our original ACCESS_FINE_LOCATION request
        if (requestCode == PERMISSIONS_REQUEST) {
            if (grantResults.length == 1 &&
                    grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                Toast.makeText(this, "location permission granted", Toast.LENGTH_SHORT).show();
            } else {
                Toast.makeText(this, "location permission denied", Toast.LENGTH_SHORT).show();
            }
        } else {
            super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        }
    }

Add Permission in AndroidMenifiest.xml file

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />