[android-developers] Re: Serializable subclass of non-serializable class
'Serializable' is ill-suited for persistence to disk. 'Parcelable' isn't much better. They're intended for in-process or inter-process transfers of data, not persistence. Don't use them. 'Serializable', in particular, imposes a huge maintenance burden, in that it locks down implementation of the class /ad aeternam/. Read Joshua Bloch's entire chapter on serialization in /Effective Java/ for the relevant warnings, dangers and gotchas. There are many. Really. Make sure you really know what you're doing before using 'Serializable'. That said, the methods that support serialization can work around your trouble, potentially. You sort of hand-roll the parts not provided upstream for you by the API. http://download.oracle.com/javase/7/docs/api/java/io/Serializable.html Don't walk into serialization without doing your homework first. Lesson one: it isn't good for persistence. Lesson two: it isn't cheap. Or maybe it's the other way around. -- Lew On Wednesday, October 5, 2011 8:20:52 AM UTC-7, Jean-Michel wrote: No, I am serialising to disk. Do you think it could work out? Any idea how to use Parcelable ? Many thanks, Jean-Michel On 5 oct, 16:43, Daniel Drozdzewski daniel.dr...@gmail.com wrote: Now luckily for you, Location in Android implements Parcelable interface, which could be of help, depending where are you sending to and receiveing from your Leg/Location related data. If it is within the same machine between a service and an activity, then you are fine. If you are passing it via network, you need to implement a DTO, that implements Serializeable and holds all the necessary data that you depend on. You then pass that DTO and with its help you create new Location object at the receiving end. HTH -- Daniel Drozdzewski -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
Re: [android-developers] Re: Serializable subclass of non-serializable class
JM, sorry I missed your reply among 100s of emails yesterday... On 5 October 2011 17:18, Jean-Michel jeanmichel.caz...@gmail.com wrote: Daniel, sorry to be a pain in the bum, but there are still 2 things I cannot figure out. First I am not sure what you mean by DTO, but from what I understand it is basicaly a place holder for the data in my non-serilizable class. I understand how to transfer dta (the one I care about) between LocationDTO and Location. It is not a place holder. It is actual data holder and Location is left alone. You do the following: 1. Define LocationDTO that implements Serializable, which will store all data that you need from Location. 2. When you are about to persist your Location to storage, you populate that DTO with the latest values from Location. 3. You serialize DTO and persist resulting stream. application is OFF here 4. Upon re-launch of your application, you read the serialized DTO from the storage, therefore de-serializing the DTO. 5. Create brand new Location (Location loc = new Location()) and populate all its properties from deserialized DTO. As you can see, you have not serialized or deserialized Location class (or any of its subclasses) at all, therefore avoiding all the troubles that you have with it. -- Daniel Drozdzewski -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
[android-developers] Re: Serializable subclass of non-serializable class
No, I am serialising to disk. Do you think it could work out? Any idea how to use Parcelable ? Many thanks, Jean-Michel On 5 oct, 16:43, Daniel Drozdzewski daniel.drozdzew...@gmail.com wrote: Now luckily for you, Location in Android implements Parcelable interface, which could be of help, depending where are you sending to and receiveing from your Leg/Location related data. If it is within the same machine between a service and an activity, then you are fine. If you are passing it via network, you need to implement a DTO, that implements Serializeable and holds all the necessary data that you depend on. You then pass that DTO and with its help you create new Location object at the receiving end. HTH -- Daniel Drozdzewski -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
Re: [android-developers] Re: Serializable subclass of non-serializable class
On 5 October 2011 16:20, Jean-Michel jeanmichel.caz...@gmail.com wrote:
No, I am serialising to disk.
Do you think it could work out?
Any idea how to use Parcelable ?
Many thanks,
Jean-Michel
Jean-Michel,
Parcelable is used for inter-process communication and is designed
specifically for that (i.e. passing the data between services and
activities).
In order to save it to disk, you have to create mentioned DTO.
It can sound serious, but it is simple:
class LocationDTO implements Serializable {
//all properties extracted from Location that you need
//... with all getters and setters.
}
When you need to preserve the location, you create this DTO, populate
all properties yourDTO.setAcuracy(yourLocation.getAcuracy());
... and preserve this DTO. Then when you need it back in memory, you
deserialise this DTO, create new Location object and populate its
properties from DTO.
--
Daniel Drozdzewski
--
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[android-developers] Re: Serializable subclass of non-serializable class
Daniel, sorry to be a pain in the bum, but there are still 2 things I
cannot figure out.
First I am not sure what you mean by DTO, but from what I understand
it is basicaly a place holder for the data in my non-serilizable
class.
I understand how to transfer dta (the one I care about) between
LocationDTO and Location.
Then, how am I stopping the default process to try to serialize the
Location parent object. At thye moment I am doing nothing, this is all
happening by default.
If you would have a link on some doc or an example that would greato-
smashing-fantastic ;).
JM
On 5 oct, 17:41, Daniel Drozdzewski daniel.drozdzew...@gmail.com
wrote:
On 5 October 2011 16:20, Jean-Michel jeanmichel.caz...@gmail.com wrote:
No, I am serialising to disk.
Do you think it could work out?
Any idea how to use Parcelable ?
Many thanks,
Jean-Michel
Jean-Michel,
Parcelable is used for inter-process communication and is designed
specifically for that (i.e. passing the data between services and
activities).
In order to save it to disk, you have to create mentioned DTO.
It can sound serious, but it is simple:
class LocationDTO implements Serializable {
//all properties extracted from Location that you need
//... with all getters and setters.
}
When you need to preserve the location, you create this DTO, populate
all properties yourDTO.setAcuracy(yourLocation.getAcuracy());
... and preserve this DTO. Then when you need it back in memory, you
deserialise this DTO, create new Location object and populate its
properties from DTO.
--
Daniel Drozdzewski
--
You received this message because you are subscribed to the Google
Groups Android Developers group.
To post to this group, send email to android-developers@googlegroups.com
To unsubscribe from this group, send email to
android-developers+unsubscr...@googlegroups.com
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