CODEWITHSUNDEEP
javastringpojo
Neel
Neel

Reputation: 2100

How to persist large strings in a POJO?

If I have a property of an object which is a large String (say the contents of a file ~ 50KB to 1 MB, maybe larger), what is the practice around declaring such a property in a POJO? All I need to do is to be able to set a value from one layer of my application and transfer it to another without making the object itself "heavy".

I was considering if it makes sense to associate an InputStream or OutputStream to get / set the value, rather than reference the String itself - which means when I attempt to read the value of the contents, I read it as a stream of bytes, rather than a whole huge string loaded into memory... thoughts?

Upvotes: 0

Views: 527

Answers (2)

phatfingers
phatfingers

Reputation: 10250

What you're describing depends largely on your anticipated use of the data. If you're delivering the contents in raw form, then there may be more efficient ways to manage it.

For example, if your app has a web interface, your app may just provide a URL for a web server to stream the contents to the requester. If it's a CLI-based app, you may be able to get away with a simple file copy. If your app is processing the file, however, then perhaps your POJO could retain only the results of that processing rather than the raw data itself.

If you wish to provide a general pattern along the lines of using POJO's with references to external streams, I would suggest storing in your POJO something akin to a URI that tells where to find the stream (like a row ID in a database or a filename or a URI) rather than storing an instance of the stream itself. In doing so, you'll reduce the number of open file handles, prevent potential concurrency issues, and will be able to serialize those objects locally if needed without having to duplicate the raw data persisted elsewhere.

Upvotes: 1

Enno Shioji
Enno Shioji

Reputation: 26882

You could have an object that supplies a stream or an iterator every time you access it. Note that the content has to live on some storage, like a file. I.e your object will store a pointer (e.g. a file path) to the storage and every time someone access it, you open a stream or create an iterator and let that party read. Note also that in order to save on memory, whoever consumes it has to make sure not to store the whole content in memory.

However, 50KB or 1MB is really tiny. Unless you have like gigabytes (or maybe hundred megabytes), I wouldn't try to do something like that.

Also, even if you have large data, it's often simpler to just use files or whatever storage you'll use.

tl;dr: Just use String.

Upvotes: 1

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