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| - | ===== 01 - Android SDK ===== | ||
| - | * Description: Development environment on Android, overview of the Android SDK | ||
| - | * Practical part: Android SDK development | ||
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| - | ==== Lecture ==== | ||
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| - | |||
| - | *{{:osp:lectures:lecture-1.pdf | Lecture Slides}} | ||
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| - | {{url>http://ocw.cs.pub.ro/courses/_media/osp/lectures/lecture-1.pdf}} | ||
| - | |||
| - | ==== Practical ==== | ||
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| - | === Resources === | ||
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| - | * Android Studio: [[http://developer.android.com/sdk/index.html#top]] | ||
| - | * Android Developers: [[https://developer.android.com/index.html]] | ||
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| - | === Files === | ||
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| - | {{:ndk:courses:lab-1.zip|}} | ||
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| - | === Task 0 - Setting up the environment === | ||
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| - | To install Android Studio on your own machine follow the step here: [[http://developer.android.com/sdk/installing/index.html?pkg=studio|Installing Android Studio]]. Android studio is already installed on the workstations in the lab. | ||
| - | |||
| - | === Task 1 - Create and run an application === | ||
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| - | Create a new Android Project in Android Studio (**Start a new Android Studio Project**). Choose a name and leave other options as they are. On the next screen choose **Phone and Tablet** and choose API level 15 or higher. Choose **Empty Activity** on the next screen. Continue to the next screen and click finish. On the sidebar on the left choose project and open ** java > student.example.com > MainActivity**. This activity is very simple right now. | ||
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| - | Run the project by clicking the green arrow on the toolbar above the editing area. Android Studio will prompt you to choose a device. Follow the steps in the next tasks to create a new virtual device. | ||
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| - | === Task 2 - Creating a virtual device === | ||
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| - | Create a virtual device in Eclipse: | ||
| - | - Click **...** next to the **Android Virtual Device** list under the **Launch emulator** option | ||
| - | - Click **Create Virtual Device**. | ||
| - | - Choose Nexus 4 or Galaxy Nexus screen resolution. Click Next. | ||
| - | - Choose Marshmallow x86 image. Download if needed. Click next. | ||
| - | - Give the device 512-1024 MBs of RAM and 64 MB VM Heap (Under Advance Options) | ||
| - | - Give the device and 200 MB SD Card. | ||
| - | - Select Use Host GPU. | ||
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| - | On Windows, if HAXM service is started, Android Virtual Devices will run virtualized. | ||
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| - | On Linux you either set it up in Eclipse, or a per project basis: | ||
| - | - Click **Run > Run configurations** from Eclipse's menu bar | ||
| - | - Under **Android Application** select your project | ||
| - | - Select the **Target** tab | ||
| - | - In the **Emulator launch parameters** pane, add as additional parameters: -qemu -enable-kvm | ||
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| - | Or you can start the device using the following command: | ||
| - | <code> | ||
| - | emulator64-x86 -avd <device_name> -gpu on -qemu -enable-kvm | ||
| - | </code> | ||
| - | If you receive an error related to OpenGLES emulation library you need to add the location of the library to the LD_LIBRARY_PATH variable. The library is located in SDK_DIRECTORY/tools/lib/. Or you can remove the **-gpu on** parameter if your application does not require complex graphical features. | ||
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| - | === Task 2 - Use ADB to transfer files and install apps === | ||
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| - | After the device boots, you can connect to it using ADB. ADB can be used from a terminal on all operating systems. | ||
| - | To get a list of connected devices use can use: | ||
| - | <code> | ||
| - | adb devices | ||
| - | </code> | ||
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| - | To get a shell on the connected device use: | ||
| - | <code> | ||
| - | adb shell | ||
| - | </code> | ||
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| - | Android devices normally come with a more limited set of commands, so a text editor might not be available. | ||
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| - | Create a text file on your machine. Copy it to the connected device using: | ||
| - | <code> | ||
| - | adb push <local> <remote> | ||
| - | </code> | ||
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| - | The file should be copied to the /sdcard/ partition on the phone. Connect to the device using adb shell, and use cat to check the contents of the file. | ||
| - | To copy from the device use: | ||
| - | <code> | ||
| - | adb pull <remote> [<local>] | ||
| - | </code> | ||
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| - | Both push and pull can be used with both directories and files. | ||
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| - | To install an application through adb use: | ||
| - | <code> | ||
| - | adb install <file> | ||
| - | </code> | ||
| - | Install LogLevel.apk (in the laboratory archive). | ||
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| - | To check all available options of the ADB use: | ||
| - | <code> | ||
| - | adb --help | ||
| - | </code> | ||
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| - | === Task 4 - Add a button === | ||
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| - | The MainActivity.java file should be displayed. If not, open it using the **Package Explorer** pane. You will find it in the **src** folder. | ||
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| - | The Activity should be very simple. It has an onCreate method which gets called when the Activity gets started and an onCreateOptionsMenu method which creates the dropdown menu. | ||
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| - | In the onCreate method the Activity calls | ||
| - | <code> | ||
| - | setContentView(R.layout.activity_main); | ||
| - | </code> | ||
| - | This sets the layout for the Activity. R is a class generated by the SDK and it maps every resource to a number. It contains subclasses for every folder found in the **res** folder, in this case **layout**. | ||
| - | Open the res/layout/activity_main.xml file. You will see the layout editor. In the **Palette** pane, find the button, and drag it to the activity. You will see the **Outline** pane to the right of the screen change to reflect this. Select the button and check its id field in the **Properties** panel, under the list of UI elements. Change the text of the button to "Press me!". Also check the id field of the TextView element. | ||
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| - | Go back to MainActivity.java. | ||
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| - | Add the following code to the onCreate method. Make sure the ids match the ones in your layout. | ||
| - | <code Java> | ||
| - | final Button b1 = (Button) findViewById(R.id.button1); | ||
| - | final TextView tv1 = (TextView) findViewById(R.id.textView1); | ||
| - | | ||
| - | b1.setOnClickListener(new OnClickListener() { | ||
| - | int n = 1; | ||
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| - | @Override | ||
| - | public void onClick(View v) { | ||
| - | tv1.setText("Hello again! " + Integer.toString(n++)); | ||
| - | } | ||
| - | }); | ||
| - | </code> | ||
| - | This gets the references to both the Button you added and the TextView that was already declared. They are declared final so they can be visible inside the new OnClickListener. The OnClickListener objects contains an onClick method which gets executed when the button is pressed. In this case, it updates the TextView to reflect the number of clicks on the button. | ||
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| - | === Task 5 - Use logcat for debugging === | ||
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| - | Start the application installed in Task 2. Make sure the **Logcat** tab is the one selected in the panel at the bottom. Type any text in the box and then click one of the buttons. A new line containing your text should appear in the **Logcat**. Depending on what button you press, the line colour will vary. It is also possible to filter these log entries: above the logs themselves there is a text entry input which allows textual filtering. It allows you to limit scope by prefixing searches with pid:, tag:, app: or text: and it accepts Java-style regular expressions. To the right of this text field there is a dropdown which allows you to select verbosity. Choosing a level will only allow messages of that level or higher to be displayed. | ||
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| - | Import the LogLevel project into Eclipse (**File > Import** and select **General > Existing project into workspace**). Look over the code. Each button has a method attached which calls a static method from the Log class. These methods generate log entries on different levels of importance: d=debug, i=info, w=warning, e=error. | ||
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| - | Add another two buttons to the application: one that generates an assert level log entry, and one that repeats the previously generated log entry, but with a higher level of importance, except in the case of assert, which will remain the same. | ||
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| - | === Task 6 - View weight === | ||
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| - | Use the LogLevel project as a start. Notice that the EditText box only takes up one line of the screen and there should be some screen space left at the bottom of the screen. Make the EditText box take up all available space. To do this, you should set the weight parameter of the EditText view to 1 (or any integer). | ||
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| - | The weight parameter is used to distribute empty screen space to the elements which need it. First, the layout builder will place all the elements for which the size is easy to determine. Then, the empty space will be distributed to the elements with weight, based on their weight: if the total weight of all elements is 4, an element with a weight of 1 will get 1/4 of the empty screen space, an element with 2 weight will get 2/4, and so on. | ||
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| - | === Task 7 - Multiple resources === | ||
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| - | In Android you can have multiple resources with the same ID. This allows building a single application for all the languages, screen resolutions or formats, and have the system select the correct resource when running the application. | ||
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| - | In the LogLevel project, notice that there is a single **layout** folder. Modify this layout to fit two screen densities: mdpi and hdpi. To do this, rename the folder **layout** to **layout-hdpi** and make a copy of it named **layout-mdpi**. This will allow the system to select the mdpi layout for systems with medium dpi or lower, and the hdpi layout for the rest. Modify the mdpi layout to display the buttons on two columns instead of a single button on each row. Use multiple horizontal LinearLayouts. | ||
