Its an application that is calling the ZXing barcode reader on button push, after scanning in shows you the code and you can put in an amount (how much you want to order from that product), then you go next scan, so on so on...I need to store this data. In my main window under the scan button, i will have a show scanned list, with all the scanned items plus the amount of each. And i will have a send button which sends a this list in a .txt or a .csv file via bluetooth to PC. And after closing the application with exit button, or with the back key, this list needs to be destroyed , so when i start the application again, there is a fresh, new list. First i thought, on using SQLite, but my costumer wants a simple program, without db. I could just need a few ideas on storing, data else how. Like an array list, but i dont know how hard is it to handle such a storing bethod, with editing or deleting and such. Or directly saving it into a .CSV file? Any idea is welcome.
Thanks you.
create a Bean class say Product which contains the attributes which you want to display on your list view.
Take a ArrayList
store the bean objects in arraylist and finally iterate it to do your calculations.
To get the CSV, you can call the to string on the instance of arraylist.
IMO using SQLite would be your best option, it does not add that much complexity to your app. Though if you really do not want to use it, Shared Preferences is an even simpler API for storing data.
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I am working on an android application that will randomly choose a activity for people to do from an array list. I want this list to be edited by the user of the application by adding or removing activities from the list. I would like the list to be loaded when the application is opened and saved when paused, closed, or destroyed.
I cannot figure out how to store the array list an load it. I have tried to understand posts in the past about this topic but cannot make sense of how to implement them.
I you can help, it would be greatly appreciated.
You have some alternatives:
1) Use a local database (I suggest greendao for the great performance). Here's the oficial page
That way like in a conventional database you store (in the OnPause method) the data and query it the next time the user opens the app.
2) Use serialization (its convenient for small amount of data), as the previous one in the onPause method you serialize the object and deserialize it when the users open the app. Here's a tutorial about it
I'm developing an app that downloads ParseObject's data from server and populate a ListView in Fragment with it.
I read about downloading data by Service and after it's done (some kind of listener?) it would update Fragment and be accessible until user leaves the app (which is fine by me).
On the other hand - I can just store it in Bundle and retrieve it every time I get back to that Fragment, but then I'd need implement Serializable which in this case can be cumbersome: like here
Fragments are held by DrawerLayout so it's really irritating now to see loading bar everytime You change to that Fragment and I'm looking for a solution to change that to improve UX.
What do You suggest? Which approach would be better in that situation? Maybe there are things that I should be aware of before attempting to use any of these?
I think it depends on how often the data is changed on the server.
If only daily/weekly the solution must differ compared to if the data is changed every mins/hours.
If the data is kind of static then you can download it only once, and save it to SharedPreferences, or to a seperate local file or DB.
If it changes kinda often, I'd suggest to use bundles or in memory objects, so when the user reenters the app the data should be downloaded again.
The solution i'd use would be to simply convert the entire list of data to JSON, and then save it in SharedPreferences. This allows for easy reuse of the data when the user goes back to that fragment.
As you aren't saving the data across app close/reopen, a local database is not needed.
In terms of storing data in Android, would it be more efficient to use a large ArrayList or setup an SQLite database? I have ~9000 bus stops and stop names (both in String) that I need to store and I was wondering which method would be the quickest or most efficient.
An ArrayList is probably a very bad idea. I assume you want the data to be persistent, so if your user kills your app your data will be lost if you use an ArrayList. A database is persistent(unless the user clears the cache of the app). So I would highly recommend using a database over an ArrayList.
If your data does not change then you could probably have it read on startup and kept in memory while the App runs. For example, having a .json file with all the stops, read it on startup, put the data in a HashMap or something that is easy to use since you will probably lookup stuff. It would probably work fine with ~9000 entries.
If you are going to add or update information about the stops during usage then the SQLite is the better choice though.
1.) Store and retrieve your data from a SQLite DB since you want persistance. And since you say you have 9k+ rows a simple select will give you everything at once and you can easily filter the data as well if you need to
2.) At startup, put all your data into efficient memory structures like HashMaps(or in your case arraylists) and reference them throughout the app. This way you'll only do one time access.
3.) When in doubt build a DB. No harm, more efficient and easier to handle than files
To get Data for my application, I parse a Json file, with Jackson, to (lists of) custom Objects. When I start my app, I check if there is a new Json file available and ask the user if they want to download it, else I use the "old" Json file. But every time I start my app I parse the Json. Then I use the Application Class to save my list of objects an go to my data when I want, most of the time I only need one object.
From the huge list, with multiple layer nested object, I create a simple "flat" arraylist of custom objects in which I put only the data I need to create listviews (name, id, second text and url of picture). When something is clicked, i use the id to get all the data.
Parsing this whole Json file every time is pretty time consuming and makes the startup time of my application long. Ofcourse, this sucks.
And having this huge list of custom objects saved in Application Class fills a lot of memory of my device, and sometimes after some use the class gets killed, and I need to reparse again.
Is there a way I don't need to reparse all my data?
I hoped for a process like this:
new Json file
first time parse total JSON to list of multilayered custom objects
create simple list for listviews
delete/clear the big list
some clever way to get only one of the giant items, without keeping the whole list in my memory. (maybe something with Jackson).
on destroying of the application maybe save the simple list, i read something about parceable or serializable?
Anyone knows how to achieve this?
Or has an other awesome idea?
Jackson has a streaming api. Also you can parse the json in a AsyncTask (in the background) and update your user interface once the new data is ready
I'd probably store the data in a SQLite database, in line with how the Android platform was designed.
As an alternative to streaming Jackson API (which is very fast, but still has to scan through most of the content), perhaps you could just save things in different files, one per entry? Or, if there is a way to group things, in multiple files each having some subset?
Of course, if you really have tons of entries, use of SQLite as Bruce suggested makes lots of sense.
For my newest app it it one that will save multiple EditTexts where the user can enter stuff.Like say if it was a note app,how would i get them to save?
There are multiple ways to store data on Android. Read about data storage.
In your case you might have multiple text records with some metadata (time when created, etc..), so I'd recommend the database.
Check out how to store preferences with android's "SharedPreferences":
http://www.javacodegeeks.com/2011/01/android-quick-preferences-tutorial.html
This way you can indefinitely store whatever you're working with as a string, object, etc. Also, you can check out how to work with android's SQLite Database, which might be harder to figure out when you start working with it, but it gets easier over time.