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So we're well on the way to getting this app finished.

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We just need some way now to pass the search results back to MainActivity.

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Now a good solution here would be to use something called shared preferences. Now shared preferences provides a way

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to store up data, so you can retrieve the data again next time the app starts up.

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They're not as powerful as a full database, but for many applications where you don't have to store

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a lot of data, they're ideal. And the other good thing is that they're also very easy to use, and they

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work in a similar way to the bundles that we've used before.

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So you store data in key value pairs, and retrieve the data items by specifying the key.

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So I'm going to add the code now to the onQueryTextSubmit function in search activity, just so you 

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can see what it does.

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So onQueryTextSubmit, we're going to add code after the logging,

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and we'll start with val sharedPref equals PreferenceManager.getDefaultSharedPreferences, then parentheses,

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and it's going to be applicationContext.

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Then we're going to do sharedPref dot edit, we're actually calling the edit function, so there's parentheses dot putString

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parentheses, and it's going to be flickr query

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comma space query closing parentheses dot

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apply. We're calling the apply function, and then we're going to do searchView question mark dot

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clearFocus, and then we're going to leave the call to finish and then return true.

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So what we're doing here is starting out on line 41. We're getting a shared preferences object by calling the Preference

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Manager's getDefaultSharedPreferences function, passing it a context.

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Now here we want to pass the application context rather than using this, because the date is going to

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be retrieved by a different activity to the one that saved it.

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Now SearchActivity will store the data and MainActivity will retrieve it.

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Now we have to call the edit function on the next line, line 42, to put the shared preferences into a writable

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state, and then we use the, we call the putString function to store the search query string.

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Now we store the string using the flickr query constant that we defined in base activity as the key. Now

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MainActivity and SearchActivity can both use the same constant, which ensures that they're both using

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the same key when saving and retrieving the data, and the data's then installed when we call the apply function.

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Now it's not obvious why we need to call clear focus in there,

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and you wouldn't normally find out what problem it solves, unless you tested the app on a device with

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an external keyboard.

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Now fortunately our emulators

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can use the PC's keyboard, so you can spot the strange behavior if we leave that out.

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Now the problem it fixes, is if you type a search query, then use the keyboard's enter key to submit it.

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Now when you do that the search icon in MainActivity

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also receives a click event, and just launches search activity again.

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And in fact you saw me do that in the previous video,

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when I pressed enter, entering a search query before I ended up actually correctly pressing the arrow

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down the bottom right hand corner.

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So I'm going to leave you to comment that line out and try it, so you can see why we need to remove focus from

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the toolbar before returning to MainActivity.

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And remember that you'll only see the different behavior when you press enter on an external keyboard. Alright so

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to get the data back,

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we just read the same key from the shared preference when main activity resumes.

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So let's go back and edit the MainActivity onResume function, and put some code in there. So I'm going to

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leave the call to super onResume. On the next line we'll do val 

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sharedPref is equal to, and its PreferenceManager.getDefaultSharedPreferences application context

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again. Then we're going to do val query result is equal to sharedPref.getString parentheses, and it's going to be

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flickr underscore query comma and two double quotes, closing parentheses.

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Next we're going to write a bit of code here. We're going to put if parentheses queryResult

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dot isNotEmpty,

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and we'll just add a blank

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code block for now. Then on the next line we're going to do some logging,

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so Log.d parentheses TAG comma double quotes dot onResume ends.

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So basically this is just the reverse of what we did to store the data.

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So we're creating a shared preferences object on line 120, using exactly the same code actually,

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then using the getString function to read the search string from the stored shared preferences on line

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21. Now there's no point downloading

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anything

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if no search criteria was specified, so we're checking to make sure the query result string isn't empty

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before attempting to download and parse the data.

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Or at least that's the code we're going to be using when we start filling that out from line 24. The getString

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function will attempt to retrieve the data stored with the key flickr query,

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but if it can't find the data with that key, it's going to return the second value we've passed it, an empty string

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in this case. So that's what this second argument's all about.

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Passing an empty string allows us to check to make sure we did get a search term from the user. OK.

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So if the user did specify something to search for, then we just repeat the code in onCreate to

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download the new data.

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And in fact we don't need to repeat it.

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We can just move that code into onResume.

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Remember that onResume's called after onCreate.

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So what I'm going to do is cut three lines from onCreate, and paste them into this empty if block in the

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onResume function. So back to onCreate. So the three lines

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that we want are these here,

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val

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url, the val getRawData and then the execute. So I'm going to copy those,

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or cut those rather. I'll just clear that up a little bit. Then go down to the resume, the

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onResume function.

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I'm going to paste that in here.

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So that's now called in the onResume function.

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And again, just to repeat, onResume's called after on Create.

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So therefore by putting it in onResume, we still guarantee that this code is going to be executed.

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Alright, so at this point all that remains to do, is to pass query result to the Create uri function, instead

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of the hardcoded string Android Oreo that we've currently got over here.

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So let's do that. Let's get rid of this, remove the hardcoded string there,

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and we're going to replace that instead with queryResult.

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Alright so that should work now,

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so let's test it.

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Now this time when I ran the app there's no data displayed, but that's because there wasn't any shared preference

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data to retrieve.

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So we have to do a search before we get any photo's returned. I'm going to go ahead and search for marshmallow

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again.

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And success as you can see there. We've got a load of photo's tagged now with marshmallow.

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Now we can narrow that down a little bit by searching for Android marshmallow.

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So let's try that, android comma marshmallow,

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and you can see we're getting some different results based on that as well,

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not particularly appropriate to Android marshmallow

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so let's just try another one to make sure.

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We'll try android 

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nougat,

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and we've got some more computer related results there, android nougat showing. So clearly that's working fine.

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Alright.

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So that's great,

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but what happens if a user decides that they don't want to search though, and clicks the X to cancel.

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Let's try that.

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So if they're here and they decide that they don't want to proceed with a search, click on X. Now that's not good.

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It's closed the search view but it doesn't return to MainActivity.

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But we saw, if you recall, an onClose function in the documentation, so we can implement that listener

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and call finish if the user closes the search view instead of submitting a search.

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So let's go ahead and create that, or add that rather, to the onCreateOptionsMenu function in Search

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Activity.

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We want to add it down here, before the closing onCreateOptionsMenu

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log entry, so add it there.

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Let's add a bit of space.

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So I'm going to do searchView question mark dot, we're going to set an onCloseListener, like so, and the code we want to execute in

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there is finish and then false.

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So now that we've done that we should be able to run this, and then that method will be called back.

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So let's try that, let's go into search and this time we'll close, and it correctly goes back to MainActivity as

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you can see. That's fantastic, cancelling a search now works,

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and that's our app just about finished. But there is one thing we should probably add. Now to show what that is,

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I'm going to see firstly, by doing a search,

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it there's any photos of blue monkeys driving Porsche cars in a hurricane.

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So I'm going to use a search term, blue monkey, Porsche, hurricane

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search, and not surprisingly we don't get any photos appearing. Now in that scenario,

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it would be nice to show some sort of message to let the user know that no photos matched the query,

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and that'll actually let them know that the app's still working.

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It hasn't failed in some way.

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Now the easiest way to do that is to modify the recycler view adapter,

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and we're going to have to get it to fib slightly.

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So I'm going to finish the video here, and in the next one we'll see why it's sometimes necessary to

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get your classes to tell lies.

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See you in the next video.