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So chances are when you're building your application you are going to be using

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some type of external resources.

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Now these might be video files, audio files, images, XML files, but it's likely

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you are going to be using some of these types of assets,

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so it's good to know how to actually reference assets in your application.

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So as I've shown you already in a couple of movies, the resources for your

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application are stored in this resource directory, which is just res for short,

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and some of the ones that are included automatically are layout.

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This is where our XML layouts are which define our UI.

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Inside of the values folder, this is where we actually have values that are used

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throughout our application, and here's one called strings.xml.

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So the way this works is we have an XML file here, and we have certain string

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resources. So any where in my application where I want it to say Hello World Main,

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I am actually going to reference this resource.

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So why do we keep it external?

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Well, obviously for globalization or internationalization of our application, we

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can actually provide different folders for different languages.

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That way, all we have to do is to go and to create a new XML file in a

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different language.

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We don't have to go through all of our application code and fix things

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that we've hard coded.

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But there are lots of other types of resources that we can store in here.

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So I am quickly go to the Android Developer site.

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One of the things you are going to want to get very familiar with is this Dev Guide.

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This contains tons and tons of useful information for you as you are

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building applications.

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So I am going to go to Application Resources here and then click on

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Providing Resources.

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This is just a good overview of how resources are used and accessed in Android.

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But of particular interest, if we scroll down, here we have the different types

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of directories that are supported in the Resources directory.

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So we have an anim folder, which is obviously short for animation, and this is

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where we can provide XML files that define animations, and we are going to be

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getting into that in a later movie.

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If we want to have a list of colors that our application uses in XML, we can put

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it in a color folder.

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Any of our images, or even XML-defined graphics, are in the drawable directory.

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Layouts contain our XML layouts.

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If we want to create menus, like option menus, which we will be doing in another

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movie, we are going to save them into the menu directory.

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raw is the folder where we actually store raw streams of data, and this is useful

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for video and audio, so things that are accessed just as raw streams of data.

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And then values, like I mentioned contains, simple values like strings,

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integers, and colors.

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And then lastly we have an xml directory if we want to bundle XML files with our

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application and reference them, we use the XML directory.

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Now you may be wondering right here what is this assets folder?

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Well, assets folder is basically a folder that you can put resources in, but

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they're not referenced by an ID in the application.

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There are no IDs generated for those resources.

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And in general, I like it best to keep all of my resources inside of this res directory.

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So let's actually bring in a few different types of assets.

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So if we look in the exercise files, and we are on the desktop here, go into

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exercise files, into the assets folder, there are some assets that I have

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included for you, and they range from audio files, to video files, to images.

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Let's just import some of these.

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So the easiest way to import things into our Android project here is just to select them.

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Let's say I want to import these two images. And I am just going to drag them

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into the drawable directory, and it's going to ask us, "How do we want to import

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them into the project?"

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We want to copy those files, and now we have them as part of our project.

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Now one of things I am sure you are noticing is this directory is not drawable.

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It's drawable-hdpi. And this is for high-DPI devices, and then we have another

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folder for low-DPI devices, and medium-DPI devices, and this is another

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powerful feature of Android.

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Basically, we can put different assets that we want to use for these different

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DPI screens, and the system will automatically pull out the correct ones based on

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the user's actual hardware that they're using.

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And we are going to get into this in another movie, but just know that by

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putting them in the hdpi folder, even if you are on a medium- or low-DPI device,

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it is still going to use these.

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That's all you need to worry about for now.

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So now, if we actually go in this gen folder, you can see--and this is the

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file, like I mentioned before, that you don't want to edit, but it is helpful to look at--

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we can see that what happens as you add resources to your project, Android is

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actually adding properties in here to reference.

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So we have that Amsterdam photo, and it's created an ID that we can use to

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reference it throughout our project.

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Now we don't actually give this number in our project. We actually use another

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method to actually get to this ID, so let's take a look at that.

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I have just created a blank project here.

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There has been nothing done to this project, except we just imported those assets.

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So I am going to go into the layout, and I am going to get rid of this TextView.

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Another thing to know about this graphical layout here is that we can change

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the size of our display to see how it's going to look on different sizes, so now it's QVGA.

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If we wanted to see what it looked like on a WVGA, which what our emulator is

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at, we can choose that.

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Now this is a little big for my resolution here, so I am just going to lower here,

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to something like that. This is fine.

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So what we are going to do is we are going to add an ImageView to our layout here.

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Again, this is something that allows us to, obviously to display an image.

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Well, let's say I want to display this Amsterdam image that I imported.

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So I can do this by going into the properties here, and this is the properties

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for this ImageView. And you'll notice if I come down, we have a source property.

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By default, it's actually defaulting to the icon image that ships by default

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with every application.

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What I am going to do is change it.

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So I am just going to click here and click on this button, and this is going to

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allow me to choose any items from my drawable directory.

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So I am going to choose Amsterdam,

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click OK, and now we have our image inside of here.

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So again, that's how we actually reference things in the XML.

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Now let me actually show you in the XML view what that looks like.

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So here we can see we have the source property.

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When we are actually referencing things, we are going to use an @ symbol, and now

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we can choose from the different directories, but I want to go into drawable.

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Again, I can hit Ctrl+Space to get code hinting.

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So we are saying @ the drawable directory, give me the Amsterdam image.

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Now remember, we don't say drawable-hdpi here.

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Again, the system takes care of that. So our application only references the

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drawable folder, and then the Android system will choose the correct size

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graphic to match whatever the user's device is.

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So that's how to reference it from the XML.

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Let me show you how to reference it from the Java code.

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So let's go to our Java code, and let's say as soon as we come into our activity,

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in the onCreate, let's go ahead and set the imageView.

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So I am going to get a reference to that, iv, and again, to get our layout, we are

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going to use findViewById R.id. There's our imageView.

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Again, we are going to have to cast that to imageView.

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Now let's say we actually want to set the image to the Lima photo, which is the

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other photo in there. I can do setImageResource.

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So now we are going to set that image equal to one of the resources that I

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have in my project.

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Now to reference it from here, we're going to reference it to that R class, which

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is autogenerated. Then we are going to go to drawable and then to lima.

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So this, obviously we are only going to able to test it when we run the application, so

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let's go ahead and do that, and let's bring up the emulator.

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Because in our XML we referenced the Amsterdam photo, again after the onCreate

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is called, we are actually changing it and say no, show me that lima.jpg image,

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which we can see here. And this is just an energy drink that you can get in Lima, Peru.

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So again, this is how we reference resources, both from the XML and from the Java code.

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Now these things are slightly different based on the type of resource and how

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you are going to handle that resource, but just remember, whenever you add stuff

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to the resource directory, behind the scenes, Android is creating this file, which

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holds all of the references to your resources and the IDs, so that you are only

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ever referencing R.drawable.lima here.

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So the resource system takes a little bit of getting used to, but it becomes

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very, very powerful, especially when you're targeting different devices and