Saving and Retrieving Data with SharedPreferences

Now that we have our editor we can start saving our values. 0:00 We learned in a previous video that the on pause life cycle method 0:04 is a good place to save any unsaved changes. 0:07 Let's make some space at the bottom of our file and 0:11 use the Ctrl+O shortcut to override the on pause method. 0:14 Then, we can store our string using the putString method of our editor. 0:23 It takes two parameters, the key and the value. 0:28 Let's type mEditor.putString and 0:32 I'll call my key KEY_EDITTEXT. 0:39 And for the value, we'll do mEditText.getText, 0:45 which returns an editable. 0:51 Then .toString, to make it a string. 0:54 Then we can use Alt+Enter on the key to create it. 1:02 I'll name mine similar to the variable, key_edittext. 1:09 Now that we've saved our string to the editor, 1:16 we just need to add mEditor.apply 1:19 to save our changes to our shared preferences object. 1:24 We've now saved the value of our edit text in the on pause method. 1:31 All that's left is to retrieve that value in the on create method and 1:35 set the text of our edit text to that value. 1:40 We can retrieve the value by using the get string method 1:44 on a shared preference object. 1:47 When retrieving a value from a shared preference we need to provide the key for 1:50 the value and a default value to use in case that key isn't found. 1:54 In the bottom of our on create, let's retrieve our string by calling 2:00 MSharedPreferences.getString and 2:05 passing in our KEY_EDITTEXT string for 2:13 the key parameter and an empty string for the default value. 2:17 Next, let's save this value into a string called editTextString. 2:24 Lastly, let's update our edit text by typing mEditText.setText. 2:37 And we'll set it to editTextString. 2:48 The last step is to test the app to make sure it works as expected. 2:53 I'll type in some text. 3:00 And close the app by hitting the back button. 3:07 And when we reopen the app, our text is still here, perfect. 3:20 Before we go on, let's talk about removing shared preference values. 3:25 This is especially useful for 3:31 testing, or if your users want to reset an app to it's default values. 3:32 This can be done by using the clear method of a shared preference editor object. 3:38 Also, we can use the remove method, and pass in a key, to remove just one value. 3:43 Once you're done removing values, 3:51 don't forget to use the apply method to save your changes. 3:53 Shared preferences is the easiest way to store data in Android, but 3:57 only if that data can easily fit into a key value pair. 4:01 If you're interested in how to store more complicated data, like a picture or 4:05 a Java file, please check out our videos on data persistence in Android, 4:08 which are linked in the teacher's notes. 4:13 They also cover shared preferences in a little more detail. 4:15 For now, we're going to move onto a practice project 4:18 to test everything that you've learned so far. 4:21