Android KTX - Tips to strip your Kotlin codebase!

#KotlinEverywhere session at #GDGAhmedabad
Google Slide link:
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Transcript

1. Android KTX Tips to strip your Kotlin codebase! Organized by Ahmedabad Pranay Patel Android @ Simform Solutions #KotlinEverywhere
2. Motivation What heuristic do you use to know that you write maintainable code? In other words ... how do you know that the code you write is maintainable? ~ Donn Felker
3. Motivation For me, its tests and asking myself the simple question of: "If I come back to this code in 6 months, will I understand it in 30 seconds or less and will I feel confident to make a change?" ~ Donn Felker
4. What we are going to learn... 0. What is android-ktx 1. Why it is useful? 2. Add Android KTX in your project 3. Explore Android KTX apis 4. Try to build your own KTX 5. “SAMAPAN” - wrap up!
5. There is no magic!
6. What is android-ktx
7. • It’s a collection of Kotlin extension functions that will beautify and give a Kotlin-ish touch to existing Android APIs
8. Why it is useful?
9. • Specifically design for Android apis • Kotlin language feature • Writing a dot after any object! • Avoid code duplication.
10. Enough Talk , Show Us The Code!
11. Add Android KTX in your project
12. repositories { google() } dependencies { // Core KTX implementation 'androidx.core:core-ktx:1.1.1' }
13. • androidx.fragment:fragment-ktx:$version • androidx.palette:palette-ktx:$version • androidx.sqlite:sqlite-ktx:$version • androidx.collection:collection-ktx:$version • androidx.lifecycle:lifecycle-viewmodel-ktx:$version • androidx.lifecycle:lifecycle-reactivestreams-ktx:$version • androidx.navigation:navigation-runtime-ktx:$version • androidx.navigation:navigation-fragment-ktx:$version • androidx.navigation:navigation-ui-ktx:$version • androidx.work:work-runtime-ktx:$version • com.google.android.play:core-ktx:$version Pick the one that you want!
14. Explore Android KTX apis
15. Layout Binding // Activity class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) } } // Fragment class MainFragment:Fragment() { override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? { return layoutInflater.inflate(R.layout.my_fragment_layout, container, false) } }
16. Layout Binding using KTX // Activity class MainActivity : AppCompatActivity(R.layout.activity_main) // Fragment class MainFragment : Fragment(R.layout.my_fragment_layout)
17. val newFragment = ExampleFragment() val transaction = supportFragmentManager.beginTransaction() transaction.replace(R.id.fragment_container, newFragment) transaction.addToBackStack(null) transaction.commitAllowingStateLoss() Fragment Transaction
18. val newFragment = ExampleFragment() supportFragmentManager.transaction(now = false, allowStateLoss = true) { replace(R.id.fragment_container, newFragment, ExampleFragment.TAG) } val newFragment = ExampleFragment() val transaction = supportFragmentManager.beginTransaction() transaction.replace(R.id.fragment_container, newFragment) transaction.addToBackStack(null) transaction.commitAllowingStateLoss() Fragment Transaction using KTX
19. // androidx.fragment:fragment-ktx FragmentManager.transaction(now: Boolean = false, allowStateLoss: Boolean = false, body: FragmentTransaction.() -> Unit) Fragment Transaction KTX Code
20. db.beginTransaction() try { ... db.setTransactionSuccessful() } finally { db.endTransaction() } Database Transaction
21. db.transaction { // insert, update, delete } db.beginTransaction() try { ... db.setTransactionSuccessful() } finally { db.endTransaction() } Database Transaction using KTX
22. HtmlCompat.fromHtml("<b>HTML</b>", HtmlCompat.FROM_HTML_MODE_LEGACY) HtmlCompat.toHtml(SpannableString.valueOf("TEST VALUE"), HtmlCompat.TO_HTML_PARAGRAPH_LINES_CONSECUTIVE) Html parsing
23. Html parsing using KTX HtmlCompat.fromHtml("<b>HTML</b>", HtmlCompat.FROM_HTML_MODE_LEGACY) HtmlCompat.toHtml(SpannableString.valueOf("TEST VALUE"), HtmlCompat.TO_HTML_PARAGRAPH_LINES_CONSECUTIVE) "<b>HTML</b>".parseAsHtml() SpannableString.valueOf("TEST VALUE").toHtml() // androidx.core:core-ktx
24. inline fun String.parseAsHtml( flags: Int = FROM_HTML_MODE_LEGACY, imageGetter: ImageGetter? = null, tagHandler: TagHandler? = null ): Spanned = HtmlCompat.fromHtml(this, flags, imageGetter, tagHandler) inline fun Spanned.toHtml( option: Int = TO_HTML_PARAGRAPH_LINES_CONSECUTIVE ): String = HtmlCompat.toHtml(this, option) Html parsing KTX code
25. fun getBitmapFromDrawable(context: Context, userDrawable: Drawable): Bitmap { val bitmap = Bitmap.createBitmap( userDrawable.intrinsicWidth, userDrawable.intrinsicHeight, Bitmap.Config.ARGB_8888 ) val canvas = Canvas(bitmap) userDrawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight()) userDrawable.draw(canvas) return bitmap } Get Bitmap from Drawable
26. // androidx.core:core-ktx val drawableUser = ContextCompat.getDrawable(this, R.drawable.ic_launcher_background)?:return val bitmap = drawableUser.toBitmap() Get Bitmap using KTX
27. drawableUser.setBounds( drawableUser.bounds.left, 26, drawableUser.bounds.right, drawableUser.bounds.bottom) Set Drawable bound
28. drawableUser.setBounds( drawableUser.bounds.left, 26, drawableUser.bounds.right, drawableUser.bounds.bottom) drawableUser.updateBounds(top = 26) Set Drawable bound using KTX
29. val spanValue = SpannableString("Hello Ahmedabad!") spanValue.setSpan( ForegroundColorSpan(Color.RED),6,16, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE) spanValue.setSpan(StyleSpan(BOLD),6,16, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE) Hello Ahmedabad! Hello Ahmedabad! Get Spannable string
30. val spanValue = SpannableString("Hello Ahmedabad!") spanValue.setSpan( ForegroundColorSpan(Color.RED),6,16, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE) spanValue.setSpan(StyleSpan(BOLD),6,16, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE) Hello Ahmedabad! Hello Ahmedabad! val spanValue = "Hello Ahmedabad!".toSpannable() spanValue[6..16] = StyleSpan(BOLD) spanValue[6..16] = ForegroundColorSpan(Color.RED) Get Spannable string using KTX
31. // val spanValue = SpannableString("Hello Ahmedabad!") // spanValue[6..16] inline operator fun Spannable.set(range: IntRange, span: Any) { setSpan(span, range.start, range.endInclusive, SPAN_INCLUSIVE_EXCLUSIVE) } Spannable KTX code
32. val bundle = Bundle() bundle.putInt("KEY_INT", 21) bundle.putString("KEY_NAME", "PRANAY") bundle.putIntArray("KEY_INT_ARRAY", intArrayOf(8, 87)) bundle.putBoolean("KEY_BOOLEAN", false) bundle.putStringArrayList("KEY_STRING_ARRAY", arrayListOf("test1", "test2")) Create Bundle
33. val bundle = Bundle() bundle.putInt("KEY_INT", 21) bundle.putString("KEY_NAME", "PRANAY") bundle.putIntArray("KEY_INT_ARRAY", intArrayOf(8, 87)) bundle.putBoolean("KEY_BOOLEAN", false) bundle.putStringArrayList("KEY_STRING_ARRAY", arrayListOf("test1", "test2")) bundleOf("KEY_INT" to 21, "KEY_NAME" to "PRANAY", "KEY_INT_ARRAY" to intArrayOf(8, 87), "KEY_BOOLEAN" to false, "KEY_STRING_ARRAY" to arrayListOf("test1", "test2") ) Create Bundle using KTX
34. val arrayFirst = arraySetOf(1,2,3) val arrayTwo = arraySetOf(4,5,6) arrayFirst.addAll(arrayTwo) arrayFirst.add(7) arrayFirst.add(8) arrayFirst.add(9) Collection concatenation
35. val arrayFirst = arraySetOf(1,2,3) val arrayTwo = arraySetOf(4,5,6) arrayFirst.addAll(arrayTwo) arrayFirst.add(7) arrayFirst.add(8) arrayFirst.add(9) val arrayTwo = arraySetOf(1, 2, 3) val arrayFirst = arraySetOf(4, 5, 6) + arrayTwo arrayFirst + 7 + 8 + 9 Collection concatenation using KTX
36. // androidx.collection:collection-ktx public operator fun <T> Set<T>.plus(elements: Iterable<T>): Set<T> { val result = LinkedHashSet<T>(mapCapacity( elements.collectionSizeOrNull()?.let { this.size + it } ?: this.size * 2)) result.addAll(this) result.addAll(elements) return result } Plus operator KTX code
37. class ProfileViewModel : ViewModel() { private val viewModelJob = SupervisorJob() private val uiScope = CoroutineScope(Dispatchers.Main + viewModelJob) override fun onCleared() { super.onCleared() viewModelJob.cancel() } fun fetchData() { uiScope.launch { getUserDataFromAPI() } } private suspend fun getUserDataFromAPI() = withContext(Dispatchers.Default) { // call api } } View Model Use case
38. class ProfileViewModel : ViewModel() { fun fetchData() { viewModelScope.launch { getUserDataFromAPI() } } private suspend fun getUserDataFromAPI(){ // call api } } View Model using KTX
39. public fun CoroutineScope.launch( context: CoroutineContext = EmptyCoroutineContext, start: CoroutineStart = CoroutineStart.DEFAULT, block: suspend CoroutineScope.() -> Unit ): Job { val newContext = newCoroutineContext(context) val coroutine = if (start.isLazy) LazyStandaloneCoroutine(newContext, block) else StandaloneCoroutine(newContext, active = true) coroutine.start(start, coroutine, block) return coroutine } View Model launch KTX code
40. val uriString = "https://kotlinlang.org/foo?bar#bla" val uri = uriString.toUri() // Uri object from String val fileFromUri = uri.toFile() // File object from Uri object val uriFromFile = fileFromUri.toUri() // Uri object from File object Uri using KTX
41. Try to build your own KTX
42. 1. Try to figure out a solution to a problem How to start?
43. 1. Try to figure out a solution to a problem 2. Try to write extension with Kotlin features How to start?
44. How to start? 1. Try to figure out a solution to a problem 2. Try to write extension with Kotlin features 3. Make module for functionsfunctions
45. How to start? 1. Try to figure out a solution to a problem 2. Try to write extension with Kotlin features 3. Make module for functionsfunctions 4. use/publish your module as library
46. https://github.com/BirjuVachhani/bext/wiki Discuss example library
48. Summary what we have learned... 1. How KTX make Android APIs more pleasant and easy to use 2. Add Android KTX in your project 3. Discussed Android KTX apis 4. Make your own KTX
49. @pranaypatel_
50. Pranay Patel Android @ Simform Solutions @pranaypatel_ Thank you! Simform Solutions http://gdgahmedabad.com/ https://www.simform.com
51. References... 1. https://developer.android.com/kotlin/ktx/extensions-list 2. https://www.youtube.com/watch?v=LP3PaPrIFHo 3. https://www.youtube.com/watch?v=r_19VZ0xRO8 4. Slides Code Highlighter: https://romannurik.github.io/SlidesCodeHighlighter/
52. Ask questions...
53. Photo by The Phope on Unsplash Android KTX Tips to strip your Kotlin codebase!