Storing Data on Android

Travis Himes

Introductions

• Who am I?
• What's this about?
• How can I get the most out of this?
• What are we going to do?

Shared Preferences

• Key-Value

• Android-supplied

• Simple

• Quick

• Probably widely understood

Get:

SharedPreferences sPrefs = context
   .getSharedPreferences(
      ACTIVITY_PREFRENCES,       
      Context.MODE_PRIVATE);

Write:

sPrefs
   .edit()
   .putString("CANDY_TYPE", "Butterfinger!")
   .apply();

Read:

sPrefs
   .getString(
      SHARED_PREFS_KEY, 
      "default value")

pros:

• Simple API
• Available with Android
• Same interface (post 11)

cons:

• Simple objects only
• Lost with "Clear Data"

Summary:

Local Files

• Requires Manifest Permission

• Internal or External

• Holds more than simple types

• Device Local

• Java Devs have likely worked with Files before

• Risks...

Considerations

• Internal vs External directory

• Temporary vs "Permanent"

• Dealing with File Streams

• Space concerns

  • Creating

  • Deletion

Internal/"Permanent"

File file = new File(context.getFilesDir(), filename);
-or-
FileOutputStream outputStream = openFileOutput(filename, Context.MODE_PRIVATE);

Example

String filename = "myfile";
String string = "Hello world!";
FileOutputStream outputStream;

try {
  outputStream = openFileOutput(filename, Context.MODE_PRIVATE);
  outputStream.write(string.getBytes());
  outputStream.close();
} catch (Exception e) {
  e.printStackTrace();
}

Concerns

• Buffering
• Space on Disk
• File presence
• All those exceptions

Google Drive

(Illegitimate)

• Possible, right now, via forms to store data

  • It's a hack!

• Not the best move, buuuuut

• Great for a quick and hackish solution

• Good for write, didn't have to read, so - have fun...

• Let me explain you my quick hack!

Steps to duplicate

(don't duplicate)

• Create a google form
• Attach it to a google sheet
• Look at the form's source to get the form id and the column names
• Write an http POST request to the form with the fields

• Should show up in the spreadsheet

• Test this, and never, ever, ship it

• Seriously, this is a hack, don't ship it

Parse

So...

• Parse Server is open-source

• But, it's a REST API that you're talking with at that point, and that's another whole talk topic...

Questions

Comments

?

Thanks!

@travis_himes