java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.Object.equals(java.lang.Object)' on a null object reference at com.example.en_route.CustomerMaps$5$1.onDataChange(CustomerMaps.java:224)

Example: boolean java.lang.String.equals(java.lang.Object)' on a null object reference

if (called_from != null && called_from.equalsIgnoreCase("add")) {