如何在没有数据库以及Android中没有共享首选项的情况下永久保存arrayList？

Question

I have an ArrayList with custom objects. Each custom object contains a variety of strings and numbers. I need the array to stick around even if the user leaves the activity and then wants to come back at a later time, however I don't need the array available after the application has been closed completely. I save a lot of other objects this way by using the SharedPreferences but I can't figure out how to save my entire array this way. Is this possible? Maybe SharedPreferences isn't the way to go about this? Is there a simpler method?

Answer 1

You can serialize the ArrayList using ObjectInputStream and ObjectOutputStream since all your object appear to be serializable.

Serialization is described here : http://java.sun.com/developer/technicalArticles/Programming/serialization/

In Android, the recommended place to save such files is to use the directory specified by Context.getCacheDir() so, on your Activity you simply call this.getCacheDir() to get it and then build a unique file name you feed to the ObjectStream objects.

Answer 2

If you don't need it after the application is killed maybe you can try using onSaveInstanceState() and onRestoreInstanceState() .

Here is a short example showing how to use it!