when using a permission in android

ActivityCompat.requestPermissions(this,new String[]{android.Manifest.permission.ACCESS_FINE_LOCATION}, 1);

int permissionCheck = ContextCompat.checkSelfPermission(this,android.Manifest.permission.ACCESS_FINE_LOCATION);
System.out.println("[DEBUG]ActivityWorkMain permissionCheck="+permissionCheck);

private void fn_permission() {
    if ((ContextCompat.checkSelfPermission(getApplicationContext(), 
            android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED)) {

        if ((ActivityCompat.shouldShowRequestPermissionRationale(MainActivity.this, 
                android.Manifest.permission.ACCESS_FINE_LOCATION))) {


        } else {
            ActivityCompat.requestPermissions(MainActivity.this, 
                    new String[]{android.Manifest.permission.ACCESS_FINE_LOCATION

                    },
                    REQUEST_PERMISSIONS);

        }
    } else {
        boolean_permission = true;
    }
}

@Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
    super.onRequestPermissionsResult(requestCode, permissions, grantResults);

    switch (requestCode) {
        case REQUEST_PERMISSIONS: {
            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                boolean_permission = true;

            } else {
                Toast.makeText(getApplicationContext(), "Please allow the permission", 
                        Toast.LENGTH_LONG).show();

            }
        }
    }
}