How to use Codename one Storage?

Question

I am trying to port my LWUIT application to Codename one.

I have used RMS in LWUIT and now obviously I have to transform this to Storage.

I don\'t understand

Answer 1

The easiest way to think about Storage is as a flat file system (without directories/folders).

When running on top of RMS this file system abstraction is mapped to the RMS database seamlessly for you.

Notice that init() for Storage in Codename One is no longer necessary, under LWUIT it only performed basic initialization and the name was usually ignored.

The Storage class has several methods:

InputStream createInputStream(String name)

Creates an input stream to the given storage source file

OutputStream    createOutputStream(String name)

Creates an output stream to the storage with the given name

boolean     exists(String name)

Returns true if the given storage file exists

String[]    listEntries()

Lists the names of the storage files

You can use these to just store and check if data exists. However you can also store complex objects in storage without using input/output streams by using these two methods:

 Object     readObject(String name)

Reads the object from the storage, returns null if the object isn't there

 boolean    writeObject(String name, Object o)

Writes the given object to storage assuming it is an externalizable type or one of the supported types

So to simulate something like byte[] storage you can do something like this:

Vector p = new Vector();
byte[] myData = ...;
p.addElement(myData);
p.addElement(additionalData);
Storage.getInstance().writeObject("myStore", p);

Then just read it as:

Vector p = (Vector)Storage.getInstance().read("myStore");
// p will be null if nothing was written