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smd:laboratoare:04 [2021/04/08 11:24] alexandru.chirvase [Threading in Android] |
smd:laboratoare:04 [2021/05/12 17:46] (current) adriana.draghici [Tasks] |
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| We will also briefly discuss AsyncTasks, which are not recommended and will be deprecated in the next Android release (R). | We will also briefly discuss AsyncTasks, which are not recommended and will be deprecated in the next Android release (R). | ||
| - | Because the SMD labs' scope do not include learning a new language, we will not address in this lab asynchronous programming using the **[[https://developer.android.com/topic/libraries/architecture/coroutines|coroutines]]** provided in **Kotlin**. Nonetheless, if you want to learn and code in Kotlin, or are already familiar with it, feel free to use them in your project. Useful video overview: [[https://www.youtube.com/watch?v=BOHK_w09pVA|Understand Kotlin Coroutines on Android (Google I/O'19)]]. | + | <note tip>Because this course's scope does not include learning a new language, we will not address in this lab asynchronous programming using the **[[https://developer.android.com/topic/libraries/architecture/coroutines|coroutines]]** provided in **Kotlin**. Nonetheless, if you want to learn and code in Kotlin, or are already familiar with it, feel free to use them in your project. Useful video overview: [[https://www.youtube.com/watch?v=BOHK_w09pVA|Understand Kotlin Coroutines on Android (Google I/O'19)]]. |
| + | </note> | ||
| Other threading mechanisms you can use and are not covered in this lab: | Other threading mechanisms you can use and are not covered in this lab: | ||
| * **Reactive programming** using **[[https://blog.gojekengineering.com/multi-threading-like-a-boss-in-android-with-rxjava-2-b8b7cf6eb5e2|RxJava]]** or **RxKotlin** - do not need to explicitly create threads, just choose a scheduler | * **Reactive programming** using **[[https://blog.gojekengineering.com/multi-threading-like-a-boss-in-android-with-rxjava-2-b8b7cf6eb5e2|RxJava]]** or **RxKotlin** - do not need to explicitly create threads, just choose a scheduler | ||
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| === Using Handlers === | === Using Handlers === | ||
| We need a **messaging mechanism between threads**, and Android offers [[https://developer.android.com/reference/android/os/Handler|Handlers]]. These are closely connected to other objects needed for messaging: | We need a **messaging mechanism between threads**, and Android offers [[https://developer.android.com/reference/android/os/Handler|Handlers]]. These are closely connected to other objects needed for messaging: | ||
| - | * [[https://developer.android.com/reference/android/os/Looper|Looper]] - provided to a Handler, it runs the message queue in a loop | + | * [[https://developer.android.com/reference/android/os/Looper|Looper]] - provided to a Handler, keeps a thread alive, loops through MessageQueue and sends Messages to the corresponding Handler to process it |
| * [[https://developer.android.com/reference/android/os/Message|Message]] - the message to be sent to a Handler | * [[https://developer.android.com/reference/android/os/Message|Message]] - the message to be sent to a Handler | ||
| * [[https://developer.android.com/reference/android/os/MessageQueue|MessageQueue]] - the messages dispatached to a Looper, the developer doesn't interact directly with it, most interaction is through the Handler class | * [[https://developer.android.com/reference/android/os/MessageQueue|MessageQueue]] - the messages dispatached to a Looper, the developer doesn't interact directly with it, most interaction is through the Handler class | ||
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| ===Task 2 (4p)=== | ===Task 2 (4p)=== | ||
| - | Mock the download of several files (at least 10) in parallel on multiple threads using Runnables and ThreadPoolExecutor ([[https://developer.android.com/reference/java/util/concurrent/ThreadPoolExecutor|documentation]], [[https://developer.android.com/training/multiple-threads/create-threadpool#ThreadPool|creation example]]). | + | Mock the download of several files (at least 10) in parallel on multiple threads using Runnables and ThreadPoolExecutor ([[https://developer.android.com/reference/java/util/concurrent/ThreadPoolExecutor|documentation]], [[https://www.journaldev.com/1069/threadpoolexecutor-java-thread-pool-example-executorservice|example]]). |
| * For the "mock" download, each thread should sleep a random number between 100 and 200 ms. | * For the "mock" download, each thread should sleep a random number between 100 and 200 ms. | ||
| * The UI should update in real time a text view with the following content: | * The UI should update in real time a text view with the following content: | ||
| Line 262: | Line 262: | ||
| … | … | ||
| </code> | </code> | ||
| - | * The text view must have the option android:inputType="textMultiLine". | + | * To show multiple line you can add the ''android:inputType="text"'' to the TextView |
