[Advanced-java] C-like structs?

[jorti@xxxxxxxxx (Jose Ortiz)]

Have your java classes implement Serializable. Qualify the members you
do not want to serialize with the 'transient' keyword. Use
ObjectOutputStream and ObjectInputStream to save complete object graphs.

BTW, the C/C++ example you showed fails if the struct has pointers.
Given

typedef struct MDATA {
   int x, y;
   MyClass *mc; // A pointer to a user class/struct
} * MYDATAptr;

you do get and object doing this:

file.read(&data, sizeof(MYDATA));

however, the mc member points to garbage. Implementing a serialization
mechanism in C++ requires some effort.

Jose

Jason Boyd wrote:
> 
> In C/C++, a common way to serialize data is to define a struct containing
> data in the exact packed format it would be on disk, and then (in
> pseudo-code) do this:
> 
> typedef struct MYDATA {
>    int x, y;
>    double wx, wy;
> } * MYDATAptr;
> 
> MYDATA data; // ... fill with actual data
> 
> ...
> 
> FILE file = open(filename);
> file.write(data, sizeof(MYDATA));
> file.close();
> 
> OR:
> 
> file.read(&data, sizeof(MYDATA));
> 
> Is there a way to do this in Java? That is, simply read from an input
> stream or write into an output stream the raw data of a class without
> having to write serialization code?
> 
> The reason is that I need to read heavily nested legacy files (written by
> a C app) which are entirely based on this paradigm, and which use a *lot*
> of different struct types.
> 
> Maybe I'm missing an obvious idiom, but I haven't seen a simple way to do
> this in Java... Anyone?
> 
> Jason
> 
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