Showing Revision 3 created 05/25/2016 by Udacity Robot.

1. Title:
   Find View by Id - Solution
2. Description:

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   Let's look at number 1.
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   Before I reveal the answer,
   I'm going to copy this code and
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   paste it into Android Studio.
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   I want to show you what kind
   of error would come out.
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   Now when you were solving this quiz,
   you didn't need to use Android Studio,
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   you could have solved it by just
   looking at the code here and
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   then writing in the answer.
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    So, whether or not you use
    Android Studio, it's fine with me.
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    To make the code work,
    I created a new project and
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    then I modified the activity
    main layout file so that it
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    would have a bunch of views with these
    ID's that we're going to be referencing.
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    I'm not even sure what this
    layout would look like, but
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    I just wanted to put the views in here
    with the corresponding view ID names.
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    That way, my code will work here.
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    So for number one, I pasted the code
    here, and I see that there's an error.
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    Android Studios says it cannot
    resolve the method setText.
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    If you remember from the last video,
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    I mentioned that setText
    is a TextView method.
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    That means you can only call
    this method on TextView objects.
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    In this case,
    we're calling it on nameTextView.
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    A nameTextView is declared
    to be a view object,
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    we need to change this
    to be a TextView object.
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    Then we get an error saying
    there is incompatible types.
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    A textview, an object of type
    TextView is required, but
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    instead it found an object of type view.
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    That's because find view
    by ID returns a view, and
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    this left-hand side requires a TextView.
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    That means we have to add this to cast
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    the view returned by
    findViewById into a TextView.
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    Then we can store this whole thing,
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    which is the nameTextView,
    into the left-hand side variable.
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    Then the error goes away, and we can
    set text, "Laura" on this TextView.
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    The error is on line 1, so
    I wrote the correct code right here.
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    The general explanation is that we need
    to cast this view into a TextView and
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    then store that inside
    a nameTextView variable.
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    That way,
    we can call nameTextView.setText,
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    which is a TextView method,
    on the next line of code here.
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    Let's move on to number two.
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    I'm going to copy this code and
    put it into Android Studio.
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    Here's the code I pasted in.
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    The first line of code seems to
    be correct, there's no errors.
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    But the second line has
    a red underline and
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    it says there's
    an incompatible types error.
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    It says, a string is required but
    instead it found an int.
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    To understand this better,
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    we should look up the method getMaxLines
    within the TextView documentation.
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    In the TextView documentation,
    I'm going to search for
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    the getMaxLines method.
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    And here it is.
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    There's no input parameters, and
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    the return value of this
    method is an integer.
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    So that's why Android studio was
    complaining, because this method,
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    if it's returning an integer, but
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    we were trying to store it
    into a String variable.
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    As a result, I need to change this data
    type of the variable to be an int.
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    Then the error goes away.
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    So, the return value of
    this method is an integer.
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    So, we can store it inside
    this maxLines variable.
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    There is a warning still remaining.
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    Saying that the variable
    maxLines is never used.
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    But this is just a code snippet.
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    I assume that if this
    was in a regular app we
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    would actually want to
    use this variable later.
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    So, the error's on line two and
    here's the updated code.
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    The general explanation is that
    the return value of this method should
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    be an integer.
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    Let's move on to number three.
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    Here's a code for number three.
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    I copied and pasted the code for
    number three in Android Studio.
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    There's an error message that
    says incompatible types.
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    An ImageView was required,
    but instead it found a view.
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    This is similar to the error
    we just saw with the TextView.
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    This method returns a view.
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    And, on the left-hand side, we're
    trying to store it inside an ImageView.
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    So we need to cast this view
    object into an ImageView.
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    This is valid because the view with
    the ID icon actually is an ImageView,
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    so it's okay to cast
    it into an image view.
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    Now that the right-hand side
    evaluates to an ImageView,
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    we can store that into the variable
    on the left-hand side.
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    This variable has a data type ImageView
    so now everything matches up and
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    the error is gone.
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    On the next side,
    we can call an ImageView method,
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    SetImageResource, onto
    this IconImageView object.
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    There is one remaining error saying
    that it cannot resolve symbol logo.
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    That's because I just didn't add
    an image in our app with the name logo.
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    If I added that, then the error would
    go away, so our code here is correct.
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    Here's the correct code where I
    cast this view into an ImageView.
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    Lastly, we have number 4.
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    I pasted the code here in Android Studio
    and surprisingly there's no errors.
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    The code is trying to find
    a view with the id title, and
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    that should return a view, and that gets
    stored in this variable called TextView.
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    TextView has a data type of View, so
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    that matches with the right-hand side,
    so this whole line of code is correct.
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    On the next line we're taking
    this object, which is a View And
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    we're calling a setVisibility
    method on it.
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    The method takes in one input
    parameter which is View.GONE.
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    I can check the documentation
    to verify why that is.
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     In the documentation for
     the view class, I can search for
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     the method setVisibility.
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     I can see that setVisibility is
     a method within the view class.
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     It takes this input, an integer that
     represents the visibility state.
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     The possible visibility values
     are VISIBLE, INVISIBLE, and GONE.
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     Since setVisibility is a method
     within the view class,
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     this is a valid call here.
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     There's no need to cast
     this into a TextView
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     because the method that we're calling
     is a method of the view class.
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     Now if we were trying to
     use a TextView method,
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     then we would need to
     cast it to a TextView.
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     So for this question,
     you should put no error, because
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     setVisibility is a View method, and
     it's okay to leave it as a View object.
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     These were hard questions.
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     It's okay if you didn't
     get them correct.
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     In the next test, you'll have
     a chance to practice this more.