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Getting Text from an EditText8:21 with Ben Jakuben
Getting input from an EditText is as simple as calling a method on it. But we need to make sure we do it in the right place, and that we know what to do with what the method returns.
[SOUND] 0:00 [MUSIC] 0:01 [SOUND] We just proved that we can enter text in the main field, great. 0:03 But how do we access that text and use it in our code? 0:08 >> Let's go back into our MainActivity class file. 0:12 Now notice over here I have a new class called InteractiveStoryApplication. 0:15 If you didn't watch the optional video in the last section, don't worry about this. 0:19 You do not need this. 0:22 It's only there if you went through that optional video. 0:23 So here in our class let's add a new member variable. 0:26 private EditText, and we'll call this nameField. 0:30 Could call it name EditText but I kind of get tired typing EditText over and over. 0:34 Field is a bit easier and means the same thing. 0:38 Remember that private here means that this field can only be used inside this class, 0:41 which is what we want. 0:45 We will generally make member variables private like this, 0:45 though sometimes we want them to be public or protected. 0:49 Making things public is okay, but it does open up our code to more opportunities for 0:51 misuse or unintended consequences. 0:55 Now why is onCreate protected down here? 0:59 Protected is kind of a cross between public and private. 1:01 It makes things available to other classes in the same package or 1:04 subclasses of this class. 1:07 This is useful in certain situations, but 1:09 we'll talk about that when we come across it in the future. 1:11 You may already know all about inheritance from Java, but 1:13 we haven't really talked about it much yet. 1:15 And we're going to deal with it more in the future. 1:17 Briefly though, inheritance is an object oriented concept where a class 1:19 can inherit things from a parent class by extending it as a subclass. 1:23 So we see this with MainActivity. 1:28 We are extending the AppCompatActivity class, which means that our main activity 1:30 is a subclass, or child of the AppCompatActivity class. 1:34 That means that MainActivity is the same as a regular AppCompatActivity 1:38 plus all the extra stuff that we add to it in here. 1:42 It's worth pointing out that AppCompatActivity itself extends 1:46 FragmentActivity, which extends Activity. 1:49 Every kind of special activity in Android is somehow a descendant of this 1:52 base activity class. 1:56 And if we keep walking up this parent-chain, 1:57 we end up at the mother of all objects, java.lang.Object. 1:59 There's one more thing back in here. 2:04 We haven't talked about this overwrite annotation that we see here. 2:05 Java annotations like this are hints to the compiler that help us 2:08 while developing. 2:12 They aren't actually required for the code to work. 2:13 This hint states that this method is overwriting the oncreate method 2:15 of the parent class. 2:19 We see this same thing a lot in Android. 2:21 Anyhow, we can set our new member variable here in the onCreate method. 2:23 Remember to do it after setContentView, 2:27 because that's the method that attaches our layout to the activity. 2:29 And without that, we won't have anything for the edit text to be set to. 2:32 So let's start typing nameField = and then we'll call findView by ID. 2:36 But remember that we need to cast it to the appropriate view. 2:41 Because findView by ID returns a generic view. 2:43 And editText is a subclass of the view class. 2:46 For the ID we want R.id. 2:50 and we called it nameEditText. 2:51 Now where should we try to access the value that the user typed 2:54 inside this EditText. 2:58 It won't do us much good to do anything here in the onCreate method. 2:59 Because this only runs when the activity is first created and 3:02 the EditText will be blank. 3:05 This method sets up the activity and then we're ready to accept input from the user, 3:06 that's why we put a button on the screen. 3:11 The user should enter their name before tapping on the button. 3:12 Remember what code we used when the button is tapped? 3:15 That's right, an onClickListener. 3:17 So let's add a new member variable up here, call this private Button, 3:19 startButton, And 3:24 then I'm gonna give myself a little bit more room on this screen. 3:27 I'm going to collapse the import statements, and 3:29 add a few lines at the bottom. 3:31 And now we can set button here, startButton = We'll cast to a button. 3:34 Call find view by id and type R.button nope and 3:40 Type R.id.startButton. 3:45 On the new line we can set the onClickListener for it. 3:48 Startbutton.setOnClickListener then we want to type new onClickListener and 3:51 we get a view.onClickListener with an onClick method that we can override. 3:56 Okay so in here we're going to get the user's name which is text, so 4:02 let's create a string variable and we'll name it name. 4:06 Now how can we set it, but we want to call a method on our edit text variable. 4:11 So let's type name, field, and type dot and take a look at auto complete. 4:15 Now you might be tempted to call something like two string which is here at 4:20 the top of mine. 4:23 But that would just convert the EditText object, 4:24 nameField, to its string representation, which is not what we need. 4:26 That's not the user's name. 4:30 If you're curious what it looks like, try it out and log it. 4:31 And take a look at what it prints. 4:33 We want to getText() from the EditText, so select that method and add a semicolon. 4:35 But wait, we have an error. 4:41 If we hover over it, we see that it's an incompatible types error. 4:43 It's requiring a string from the left, but 4:48 it found something called android.text.Editable. 4:51 So, what kind of type is this and how should we fix it? 4:54 Well, I know from experience, but how would you figure this out on your own? 4:57 Well, besides watching this video. 5:00 Let's try to google it. 5:02 So let's phrase our problem. 5:04 We're trying to get text from edittext and there it is from autocomplete, 5:05 and here is a few answers that look like they might be helpful. 5:11 I'll click on this first one here which is from stack overflow. 5:13 Okay, so this person is trying to get the value of an edittext field. 5:16 And if we scroll down, we can see a working example. 5:19 And this looks a lot like our own code. 5:23 So they've got an edit text here, and down inside the onClickListener they're 5:25 calling getText, and then they're changing the method toString at the end of it. 5:30 Okay so what's happening is that getText returns a different data type, 5:34 the editable data type. 5:38 And we need to convert an editable string to a regular string. 5:40 So if we call .toString here, it does the conversion for us. 5:44 And now we have the name in our variable. 5:48 Let's use a toast here to display it so that we can test it out. 5:51 I'm old fashioned and I still like to use toast messages for this purpose. 5:53 But you could certainly use something else like a snack bar message 5:56 if you're more comfortable with that. 5:59 So on a new line, let's type Toast.makeText. 6:00 For the context, let's pass in this, then we'll pass in the name. 6:04 And then we need a length, which we can use Toast.LENGTH LONG. 6:07 At the end, we want to chain the show method to make sure our 6:13 Toast actually shows up. 6:15 And we have an error. 6:17 Let's hover over it to see what it says. 6:19 So it says cannot resolve the method and 6:21 it gives us the parameter with the different parameters that we passed in. 6:23 Now this is a common error which is why I wanted to show here. 6:27 The problem is that we're dealing with this anonymous inner class. 6:30 What that means is inside this called the set on quick listener 6:34 we are creating a brand new mini class. 6:37 It's anonymous, meaning we have not defined it in its own file or 6:41 given it a name. 6:43 Because of that the scope of this variable changes. 6:45 It's now referring to this class, this anonymous class, 6:49 instead of the overall activity class, which is the context that we need. 6:52 This method now thinks that this is a view.onClickListener instead of activity 6:57 and that's why we see it in the error message down here. 7:01 It's anonymous viewed at onClickListener. 7:04 So whenever we are in an anonymous inner class like this, 7:07 we can reference the parent activity by its full name. 7:10 So instead of just this, if we type main activity.this, 7:14 we can now get the context of the parent activity. 7:18 We use these anonymous inner classes a lot in android. 7:21 They are useful because they let us create an instance of an object like 7:24 this with certain extra details, such as overloading the method. 7:27 This is generally more concise and easy to understand in creating a new subclass or 7:30 new member variable. 7:35 But, it is up to you to use whichever method you prefer. 7:36 Okay. So our error is now resolved and 7:39 if we run the app, it should build without any errors. 7:41 And now whatever we type, 7:45 in the edit text, if we tap on the button, there we go, cool. 7:47 All right. So this one example really applies to all 7:53 kinds of data input. 7:56 There might be different controls or 7:57 methods depending on the data, but knowing how to use an EditText 7:58 means that you can easily figure out how to use other types of input widgets. 8:02 Dates, for example, use a different widget on a screen, but 8:06 the basic idea to get the data is the same. 8:08 Coming up in the next section, 8:12 we'll see how to transfer that data to a new activity, where we can use it 8:13 in our story, but because practice makes perfect how about a little practice first? 8:16
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