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Jetpack @Compose Ragunath Jawahar / @ragunathjawahar

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Many years ago…

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Architecture

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MVP VIPER RIBs MVVM Redux MVC Grox MVI MVU BLoC

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View Box Box

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✅ Separation of concerns ✅ Maintainability ✅ Extensibility ✅ Testability Boilerplate ⚠

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Boilerplate ⚠

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Jetpack Compose

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• Unbundled UI Toolkit • React, Litho, Vue.js & Flutter • Declarative • Composition over inheritance • Kotlin only • “Pre-Alpha” ⛔

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FRAMEWORKS ARE NOT TOOLS FOR ORGANISING YOUR CODE, THEY ARE TOOLS FOR ORGANISING YOUR MIND – Rick Hickey

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(1/2) UIs are trees

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(2/2) ui = f(s)

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(2/2) ui = f(s)

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(2/2) ui = f(s)

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(2/2) ui = f(s)

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(2/2) ui = f(s)

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A Tale of (at least) Two States

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ui = f(s)

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// Android framework val textView = TextView(context) println(textView=>class.java) // AB android.widget.TextView // Jetpack Compose val text = Text(text = "Hello World!") println(text=>class.java) // AB kotlin.Unit No more reference to views

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// Android framework val textView = TextView(context) println(textView=>class.java) // AB android.widget.TextView // Jetpack Compose val text = Text(text = "Hello World!") println(text=>class.java) // AB kotlin.Unit No more reference to views

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// Android framework val textView = TextView(context) println(textView=>class.java) // AB android.widget.TextView // Jetpack Compose val text = Text(text = "Hello World!") println(text=>class.java) // AB kotlin.Unit No more reference to views

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// Android framework val textView = TextView(context) println(textView=>class.java) // AB android.widget.TextView // Jetpack Compose val text = Text(text = "Hello World!") println(text=>class.java) // AB kotlin.Unit No more reference to views

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// Android framework val textView = TextView(context) println(textView=>class.java) // AB android.widget.TextView // Jetpack Compose val text = Text(text = "Hello World!") println(text=>class.java) // AB kotlin.Unit No more reference to views

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// Android framework val textView = TextView(context) println(textView=>class.java) // AB android.widget.TextView // Jetpack Compose val text = Text(text = "Hello World!") println(text=>class.java) // AB kotlin.Unit No more reference to views

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// Android framework val textView = TextView(context) println(textView=>class.java) // AB android.widget.TextView // Jetpack Compose val text = Text(text = "Hello World!") println(text=>class.java) // AB kotlin.Unit No more reference to views

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// Android framework val textView = TextView(context) println(textView=>class.java) // AB android.widget.TextView // Jetpack Compose val text = Text(text = "Hello World!") println(text=>class.java) // AB kotlin.Unit No more reference to views

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// Android framework val textView = TextView(context) println(textView=>class.java) // AB android.widget.TextView // Jetpack Compose val text = Text(text = "Hello World!") println(text=>class.java) // AB kotlin.Unit No more reference to views

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// Android framework val textView = TextView(context) println(textView=>class.java) // AB android.widget.TextView // Jetpack Compose val text = Text(text = "Hello World!") println(text=>class.java) // AB kotlin.Unit No more reference to views

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// Android framework val textView = TextView(context) println(textView=>class.java) // AB android.widget.TextView // Jetpack Compose val text = Text(text = "Hello World!") println(text=>class.java) // AB kotlin.Unit No more reference to views

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@Composable fun Text( text: String, style: TextStyle? = null, textAlign: TextAlign = DefaultTextAlign, // More parameters… ) { // More code… } Composable functions

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@Composable fun Text( text: String, style: TextStyle? = null, textAlign: TextAlign = DefaultTextAlign, // More parameters… ) { // More code… } Composable functions

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@Composable fun Text( text: String, style: TextStyle? = null, textAlign: TextAlign = DefaultTextAlign, // More parameters… ) { // More code… } Composable functions

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@Composable fun Text( text: String, style: TextStyle? = null, textAlign: TextAlign = DefaultTextAlign, // More parameters… ) { // More code… } Composable functions

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A Composed Example (pun intended)

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ui = f(s)

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ui = f(s)

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@Model data class Fruit( val name: String, val price: Double = 2.0, var quantity: Int = 0 ) { val totalPrice: Double get() = quantity * price }

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@Model data class Fruit( val name: String, val price: Double = 2.0, var quantity: Int = 0 ) { val totalPrice: Double get() = quantity * price }

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@Model data class Fruit( val name: String, val price: Double = 2.0, var quantity: Int = 0 ) { val totalPrice: Double get() = quantity * price }

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@Model data class Fruit( val name: String, val price: Double = 2.0, var quantity: Int = 0 ) { val totalPrice: Double get() = quantity * price }

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@Model data class Fruit( val name: String, val price: Double = 2.0, var quantity: Int = 0 ) { val totalPrice: Double get() = quantity * price }

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@Model data class Fruit( val name: String, val price: Double = 2.0, var quantity: Int = 0 ) { val totalPrice: Double get() = quantity * price }

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@Model data class Fruit( val name: String, val price: Double = 2.0, var quantity: Int = 0 ) { val totalPrice: Double get() = quantity * price }

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@Model data class Fruit( val name: String, val price: Double = 2.0, var quantity: Int = 0 ) { val totalPrice: Double get() = quantity * price }

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@Model data class Fruit( val name: String, val price: Double = 2.0, var quantity: Int = 0 ) { val totalPrice: Double get() = quantity * price }

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@Model data class Fruit( val name: String, val price: Double = 2.0, var quantity: Int = 0 ) { val totalPrice: Double get() = quantity * price }

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@Model data class Fruit( val name: String, val price: Double = 2.0, var quantity: Int = 0 ) { val totalPrice: Double get() = quantity * price }

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@Model data class Fruit( val name: String, val price: Double = 2.0, var quantity: Int = 0 ) { val totalPrice: Double get() = quantity * price }

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ui = f(s)

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ui = f(s) ✅

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ui = f(s)

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ui = f(s)

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Stepper

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@Composable fun Stepper(count: Int, onCountChange: (Int) ^> Unit) { val onRemoveOne = { onCountChange(count - 1) } val onAddOne = { onCountChange(count + 1) } Row { Button(text = "-", onClick = if (count > 0) onRemoveOne else null) WidthSpacer(8.dp) Container(width = 24.dp) { Text(text = "$count", style = +themeTextStyle { body1 }) } WidthSpacer(8.dp) Button(text = "+", onClick = onAddOne) } }

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@Composable fun Stepper(count: Int, onCountChange: (Int) ^> Unit) { val onRemoveOne = { onCountChange(count - 1) } val onAddOne = { onCountChange(count + 1) } Row { Button(text = "-", onClick = if (count > 0) onRemoveOne else null) WidthSpacer(8.dp) Container(width = 24.dp) { Text(text = "$count", style = +themeTextStyle { body1 }) } WidthSpacer(8.dp) Button(text = "+", onClick = onAddOne) } }

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@Composable fun Stepper(count: Int, onCountChange: (Int) ^> Unit) { val onRemoveOne = { onCountChange(count - 1) } val onAddOne = { onCountChange(count + 1) } Row { Button(text = "-", onClick = if (count > 0) onRemoveOne else null) WidthSpacer(8.dp) Container(width = 24.dp) { Text(text = "$count", style = +themeTextStyle { body1 }) } WidthSpacer(8.dp) Button(text = "+", onClick = onAddOne) } }

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@Composable fun Stepper(count: Int, onCountChange: (Int) ^> Unit) { val onRemoveOne = { onCountChange(count - 1) } val onAddOne = { onCountChange(count + 1) } Row { Button(text = "-", onClick = if (count > 0) onRemoveOne else null) WidthSpacer(8.dp) Container(width = 24.dp) { Text(text = "$count", style = +themeTextStyle { body1 }) } WidthSpacer(8.dp) Button(text = "+", onClick = onAddOne) } }

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@Composable fun Stepper(count: Int, onCountChange: (Int) ^> Unit) { val onRemoveOne = { onCountChange(count - 1) } val onAddOne = { onCountChange(count + 1) } Row { Button(text = "-", onClick = if (count > 0) onRemoveOne else null) WidthSpacer(8.dp) Container(width = 24.dp) { Text(text = "$count", style = +themeTextStyle { body1 }) } WidthSpacer(8.dp) Button(text = "+", onClick = onAddOne) } }

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@Composable fun Stepper(count: Int, onCountChange: (Int) ^> Unit) { val onRemoveOne = { onCountChange(count - 1) } val onAddOne = { onCountChange(count + 1) } Row { Button(text = "-", onClick = if (count > 0) onRemoveOne else null) WidthSpacer(8.dp) Container(width = 24.dp) { Text(text = "$count", style = +themeTextStyle { body1 }) } WidthSpacer(8.dp) Button(text = "+", onClick = onAddOne) } }

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@Composable fun Stepper(count: Int, onCountChange: (Int) ^> Unit) { val onRemoveOne = { onCountChange(count - 1) } val onAddOne = { onCountChange(count + 1) } Row { Button(text = "-", onClick = if (count > 0) onRemoveOne else null) WidthSpacer(8.dp) Container(width = 24.dp) { Text(text = "$count", style = +themeTextStyle { body1 }) } WidthSpacer(8.dp) Button(text = "+", onClick = onAddOne) } }

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@Composable fun Stepper(count: Int, onCountChange: (Int) ^> Unit) { val onRemoveOne = { onCountChange(count - 1) } val onAddOne = { onCountChange(count + 1) } Row { Button(text = "-", onClick = if (count > 0) onRemoveOne else null) WidthSpacer(8.dp) Container(width = 24.dp) { Text(text = "$count", style = +themeTextStyle { body1 }) } WidthSpacer(8.dp) Button(text = "+", onClick = onAddOne) } }

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@Composable fun Stepper(count: Int, onCountChange: (Int) ^> Unit) { val onRemoveOne = { onCountChange(count - 1) } val onAddOne = { onCountChange(count + 1) } Row { Button(text = "-", onClick = if (count > 0) onRemoveOne else null) WidthSpacer(8.dp) Container(width = 24.dp) { Text(text = "$count", style = +themeTextStyle { body1 }) } WidthSpacer(8.dp) Button(text = "+", onClick = onAddOne) } }

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@Composable fun Stepper(count: Int, onCountChange: (Int) ^> Unit) { val onRemoveOne = { onCountChange(count - 1) } val onAddOne = { onCountChange(count + 1) } Row { Button(text = "-", onClick = if (count > 0) onRemoveOne else null) WidthSpacer(8.dp) Container(width = 24.dp) { Text(text = "$count", style = +themeTextStyle { body1 }) } WidthSpacer(8.dp) Button(text = "+", onClick = onAddOne) } }

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@Composable fun Stepper(count: Int, onCountChange: (Int) ^> Unit) { val onRemoveOne = { onCountChange(count - 1) } val onAddOne = { onCountChange(count + 1) } Row { Button(text = "-", onClick = if (count > 0) onRemoveOne else null) WidthSpacer(8.dp) Container(width = 24.dp) { Text(text = "$count", style = +themeTextStyle { body1 }) } WidthSpacer(8.dp) Button(text = "+", onClick = onAddOne) } }

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@Composable fun Stepper(count: Int, onCountChange: (Int) ^> Unit) { val onRemoveOne = { onCountChange(count - 1) } val onAddOne = { onCountChange(count + 1) } Row { Button(text = "-", onClick = if (count > 0) onRemoveOne else null) WidthSpacer(8.dp) Container(width = 24.dp) { Text(text = "$count", style = +themeTextStyle { body1 }) } WidthSpacer(8.dp) Button(text = "+", onClick = onAddOne) } }

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@Composable fun Stepper(count: Int, onCountChange: (Int) ^> Unit) { val onRemoveOne = { onCountChange(count - 1) } val onAddOne = { onCountChange(count + 1) } Row { Button(text = "-", onClick = if (count > 0) onRemoveOne else null) WidthSpacer(8.dp) Container(width = 24.dp) { Text(text = "$count", style = +themeTextStyle { body1 }) } WidthSpacer(8.dp) Button(text = "+", onClick = onAddOne) } }

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@Composable fun Stepper(count: Int, onCountChange: (Int) ^> Unit) { val onRemoveOne = { onCountChange(count - 1) } val onAddOne = { onCountChange(count + 1) } Row { Button(text = "-", onClick = if (count > 0) onRemoveOne else null) WidthSpacer(8.dp) Container(width = 24.dp) { Text(text = "$count", style = +themeTextStyle { body1 }) } WidthSpacer(8.dp) Button(text = "+", onClick = onAddOne) } }

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@Composable fun Stepper(count: Int, onCountChange: (Int) ^> Unit) { val onRemoveOne = { onCountChange(count - 1) } val onAddOne = { onCountChange(count + 1) } Row { Button(text = "-", onClick = if (count > 0) onRemoveOne else null) WidthSpacer(8.dp) Container(width = 24.dp) { Text(text = "$count", style = +themeTextStyle { body1 }) } WidthSpacer(8.dp) Button(text = "+", onClick = onAddOne) } }

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@Composable fun Stepper(count: Int, onCountChange: (Int) ^> Unit) { val onRemoveOne = { onCountChange(count - 1) } val onAddOne = { onCountChange(count + 1) } Row { Button(text = "-", onClick = if (count > 0) onRemoveOne else null) WidthSpacer(8.dp) Container(width = 24.dp) { Text(text = "$count", style = +themeTextStyle { body1 }) } WidthSpacer(8.dp) Button(text = "+", onClick = onAddOne) } }

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@Composable fun Stepper(count: Int, onCountChange: (Int) ^> Unit) { val onRemoveOne = { onCountChange(count - 1) } val onAddOne = { onCountChange(count + 1) } Row { Button(text = "-", onClick = if (count > 0) onRemoveOne else null) WidthSpacer(8.dp) Container(width = 24.dp) { Text(text = "$count", style = +themeTextStyle { body1 }) } WidthSpacer(8.dp) Button(text = "+", onClick = onAddOne) } }

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@Composable fun Stepper(count: Int, onCountChange: (Int) ^> Unit) { val onRemoveOne = { onCountChange(count - 1) } val onAddOne = { onCountChange(count + 1) } Row { Button(text = "-", onClick = if (count > 0) onRemoveOne else null) WidthSpacer(8.dp) Container(width = 24.dp) { Text(text = "$count", style = +themeTextStyle { body1 }) } WidthSpacer(8.dp) Button(text = "+", onClick = onAddOne) } }

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@Composable fun Stepper(count: Int, onCountChange: (Int) ^> Unit) { val onRemoveOne = { onCountChange(count - 1) } val onAddOne = { onCountChange(count + 1) } Row { Button(text = "-", onClick = if (count > 0) onRemoveOne else null) WidthSpacer(8.dp) Container(width = 24.dp) { Text(text = "$count", style = +themeTextStyle { body1 }) } WidthSpacer(8.dp) Button(text = "+", onClick = onAddOne) } }

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@Composable fun Stepper(count: Int, onCountChange: (Int) ^> Unit) { val onRemoveOne = { onCountChange(count - 1) } val onAddOne = { onCountChange(count + 1) } Row { Button(text = "-", onClick = if (count > 0) onRemoveOne else null) WidthSpacer(8.dp) Container(width = 24.dp) { Text(text = "$count", style = +themeTextStyle { body1 }) } WidthSpacer(8.dp) Button(text = "+", onClick = onAddOne) } }

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@Composable fun Stepper(count: Int, onCountChange: (Int) ^> Unit) { val onRemoveOne = { onCountChange(count - 1) } val onAddOne = { onCountChange(count + 1) } Row { Button(text = "-", onClick = if (count > 0) onRemoveOne else null) WidthSpacer(8.dp) Container(width = 24.dp) { Text(text = "$count", style = +themeTextStyle { body1 }) } WidthSpacer(8.dp) Button(text = "+", onClick = onAddOne) } }

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@Composable fun Stepper(count: Int, onCountChange: (Int) ^> Unit) { val onRemoveOne = { onCountChange(count - 1) } val onAddOne = { onCountChange(count + 1) } Row { Button(text = "-", onClick = if (count > 0) onRemoveOne else null) WidthSpacer(8.dp) Container(width = 24.dp) { Text(text = "$count", style = +themeTextStyle { body1 }) } WidthSpacer(8.dp) Button(text = "+", onClick = onAddOne) } }

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@Composable fun Stepper(count: Int, onCountChange: (Int) ^> Unit) { val onRemoveOne = { onCountChange(count - 1) } val onAddOne = { onCountChange(count + 1) } Row { Button(text = "-", onClick = if (count > 0) onRemoveOne else null) WidthSpacer(8.dp) Container(width = 24.dp) { Text(text = "$count", style = +themeTextStyle { body1 }) } WidthSpacer(8.dp) Button(text = "+", onClick = onAddOne) } }

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@Composable fun Stepper(count: Int, onCountChange: (Int) ^> Unit) { val onRemoveOne = { onCountChange(count - 1) } val onAddOne = { onCountChange(count + 1) } Row { Button(text = "-", onClick = if (count > 0) onRemoveOne else null) WidthSpacer(8.dp) Container(width = 24.dp) { Text(text = "$count", style = +themeTextStyle { body1 }) } WidthSpacer(8.dp) Button(text = "+", onClick = onAddOne) } }

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@Composable fun Stepper(count: Int, onCountChange: (Int) ^> Unit) { val onRemoveOne = { onCountChange(count - 1) } val onAddOne = { onCountChange(count + 1) } Row { Button(text = "-", onClick = if (count > 0) onRemoveOne else null) WidthSpacer(8.dp) Container(width = 24.dp) { Text(text = "$count", style = +themeTextStyle { body1 }) } WidthSpacer(8.dp) Button(text = "+", onClick = onAddOne) } }

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@Composable fun Stepper(count: Int, onCountChange: (Int) ^> Unit) { val onRemoveOne = { onCountChange(count - 1) } val onAddOne = { onCountChange(count + 1) } Row { Button(text = "-", onClick = if (count > 0) onRemoveOne else null) WidthSpacer(8.dp) Container(width = 24.dp) { Text(text = "$count", style = +themeTextStyle { body1 }) } WidthSpacer(8.dp) Button(text = "+", onClick = onAddOne) } }

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@Composable fun Stepper(count: Int, onCountChange: (Int) ^> Unit) { val onRemoveOne = { onCountChange(count - 1) } val onAddOne = { onCountChange(count + 1) } Row { Button(text = "-", onClick = if (count > 0) onRemoveOne else null) WidthSpacer(8.dp) Container(width = 24.dp) { Text(text = "$count", style = +themeTextStyle { body1 }) } WidthSpacer(8.dp) Button(text = "+", onClick = onAddOne) } }

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Stepper

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Stepper ✅

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Fruit Row

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@Composable fun FruitRow(fruit: Fruit) { Padding(padding = EdgeInsets(left = 16.dp, right = 16.dp)) { FlexRow { expanded(1.0f) { Text(text = "${fruit.name} ($${fruit.totalPrice})", style = +themeTextStyle { h6 }) } inflexible { Stepper(fruit.quantity, onCountChange = { fruit.quantity = it }) } } } }

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@Composable fun FruitRow(fruit: Fruit) { Padding(padding = EdgeInsets(left = 16.dp, right = 16.dp)) { FlexRow { expanded(1.0f) { Text(text = "${fruit.name} ($${fruit.totalPrice})", style = +themeTextStyle { h6 }) } inflexible { Stepper(fruit.quantity, onCountChange = { fruit.quantity = it }) } } } }

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@Composable fun FruitRow(fruit: Fruit) { Padding(padding = EdgeInsets(left = 16.dp, right = 16.dp)) { FlexRow { expanded(1.0f) { Text(text = "${fruit.name} ($${fruit.totalPrice})", style = +themeTextStyle { h6 }) } inflexible { Stepper(fruit.quantity, onCountChange = { fruit.quantity = it }) } } } }

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@Composable fun FruitRow(fruit: Fruit) { Padding(padding = EdgeInsets(left = 16.dp, right = 16.dp)) { FlexRow { expanded(1.0f) { Text(text = "${fruit.name} ($${fruit.totalPrice})", style = +themeTextStyle { h6 }) } inflexible { Stepper(fruit.quantity, onCountChange = { fruit.quantity = it }) } } } }

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@Composable fun FruitRow(fruit: Fruit) { Padding(padding = EdgeInsets(left = 16.dp, right = 16.dp)) { FlexRow { expanded(1.0f) { Text(text = "${fruit.name} ($${fruit.totalPrice})", style = +themeTextStyle { h6 }) } inflexible { Stepper(fruit.quantity, onCountChange = { fruit.quantity = it }) } } } }

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@Composable fun FruitRow(fruit: Fruit) { Padding(padding = EdgeInsets(left = 16.dp, right = 16.dp)) { FlexRow { expanded(1.0f) { Text(text = "${fruit.name} ($${fruit.totalPrice})", style = +themeTextStyle { h6 }) } inflexible { Stepper(fruit.quantity, onCountChange = { fruit.quantity = it }) } } } }

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@Composable fun FruitRow(fruit: Fruit) { Padding(padding = EdgeInsets(left = 16.dp, right = 16.dp)) { FlexRow { expanded(1.0f) { Text(text = "${fruit.name} ($${fruit.totalPrice})", style = +themeTextStyle { h6 }) } inflexible { Stepper(fruit.quantity, onCountChange = { fruit.quantity = it }) } } } }

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@Composable fun FruitRow(fruit: Fruit) { Padding(padding = EdgeInsets(left = 16.dp, right = 16.dp)) { FlexRow { expanded(1.0f) { Text(text = "${fruit.name} ($${fruit.totalPrice})", style = +themeTextStyle { h6 }) } inflexible { Stepper(fruit.quantity, onCountChange = { fruit.quantity = it }) } } } }

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@Composable fun FruitRow(fruit: Fruit) { Padding(padding = EdgeInsets(left = 16.dp, right = 16.dp)) { FlexRow { expanded(1.0f) { Text(text = "${fruit.name} ($${fruit.totalPrice})", style = +themeTextStyle { h6 }) } inflexible { Stepper(fruit.quantity, onCountChange = { fruit.quantity = it }) } } } }

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@Composable fun FruitRow(fruit: Fruit) { Padding(padding = EdgeInsets(left = 16.dp, right = 16.dp)) { FlexRow { expanded(1.0f) { Text(text = "${fruit.name} ($${fruit.totalPrice})", style = +themeTextStyle { h6 }) } inflexible { Stepper(fruit.quantity, onCountChange = { fruit.quantity = it }) } } } }

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@Composable fun FruitRow(fruit: Fruit) { Padding(padding = EdgeInsets(left = 16.dp, right = 16.dp)) { FlexRow { expanded(1.0f) { Text(text = "${fruit.name} ($${fruit.totalPrice})", style = +themeTextStyle { h6 }) } inflexible { Stepper(fruit.quantity, onCountChange = { fruit.quantity = it }) } } } }

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@Composable fun FruitRow(fruit: Fruit) { Padding(padding = EdgeInsets(left = 16.dp, right = 16.dp)) { FlexRow { expanded(1.0f) { Text(text = "${fruit.name} ($${fruit.totalPrice})", style = +themeTextStyle { h6 }) } inflexible { Stepper(fruit.quantity, onCountChange = { fruit.quantity = it }) } } } }

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@Composable fun FruitRow(fruit: Fruit) { Padding(padding = EdgeInsets(left = 16.dp, right = 16.dp)) { FlexRow { expanded(1.0f) { Text(text = "${fruit.name} ($${fruit.totalPrice})", style = +themeTextStyle { h6 }) } inflexible { Stepper(fruit.quantity, onCountChange = { fruit.quantity = it }) } } } }

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@Composable fun FruitRow(fruit: Fruit) { Padding(padding = EdgeInsets(left = 16.dp, right = 16.dp)) { FlexRow { expanded(1.0f) { Text(text = "${fruit.name} ($${fruit.totalPrice})", style = +themeTextStyle { h6 }) } inflexible { Stepper(fruit.quantity, onCountChange = { fruit.quantity = it }) } } } }

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@Composable fun FruitRow(fruit: Fruit) { Padding(padding = EdgeInsets(left = 16.dp, right = 16.dp)) { FlexRow { expanded(1.0f) { Text(text = "${fruit.name} ($${fruit.totalPrice})", style = +themeTextStyle { h6 }) } inflexible { Stepper(fruit.quantity, onCountChange = { fruit.quantity = it }) } } } }

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@Composable fun FruitRow(fruit: Fruit) { Padding(padding = EdgeInsets(left = 16.dp, right = 16.dp)) { FlexRow { expanded(1.0f) { Text(text = "${fruit.name} ($${fruit.totalPrice})", style = +themeTextStyle { h6 }) } inflexible { Stepper(fruit.quantity, onCountChange = { fruit.quantity = it }) } } } }

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@Composable fun FruitRow(fruit: Fruit) { Padding(padding = EdgeInsets(left = 16.dp, right = 16.dp)) { FlexRow { expanded(1.0f) { Text(text = "${fruit.name} ($${fruit.totalPrice})", style = +themeTextStyle { h6 }) } inflexible { Stepper(fruit.quantity, onCountChange = { fruit.quantity = it }) } } } }

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@Composable fun FruitRow(fruit: Fruit) { Padding(padding = EdgeInsets(left = 16.dp, right = 16.dp)) { FlexRow { expanded(1.0f) { Text(text = "${fruit.name} ($${fruit.totalPrice})", style = +themeTextStyle { h6 }) } inflexible { Stepper(fruit.quantity, onCountChange = { fruit.quantity = it }) } } } }

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@Composable fun FruitRow(fruit: Fruit) { Padding(padding = EdgeInsets(left = 16.dp, right = 16.dp)) { FlexRow { expanded(1.0f) { Text(text = "${fruit.name} ($${fruit.totalPrice})", style = +themeTextStyle { h6 }) } inflexible { Stepper(fruit.quantity, onCountChange = { fruit.quantity = it }) } } } }

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Fruit Row

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Fruit Row ✅

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State?

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override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContent { FruitApp { val apple = +memo { Fruit("Apple") } FruitRow(apple) } } }

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override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContent { FruitApp { val apple = +memo { Fruit("Apple") } FruitRow(apple) } } }

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override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContent { FruitApp { val apple = +memo { Fruit("Apple") } FruitRow(apple) } } }

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override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContent { FruitApp { val apple = +memo { Fruit("Apple") } FruitRow(apple) } } }

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override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContent { FruitApp { val apple = +memo { Fruit("Apple") } FruitRow(apple) } } }

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override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContent { FruitApp { val apple = +memo { Fruit("Apple") } FruitRow(apple) } } }

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override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContent { FruitApp { val apple = +memo { Fruit("Apple") } FruitRow(apple) } } }

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override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContent { FruitApp { val apple = +memo { Fruit("Apple") } FruitRow(apple) } } }

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override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContent { FruitApp { val apple = +memo { Fruit("Apple") } FruitRow(apple) } } }

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{ Demo }

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Future • Increased productivity • Higher-level of abstraction • Wider use of existing of skillset • Collaboration • Design • Product • Other platforms?

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Resources • https://developer.android.com/jetpack/compose • http://intelligiblebabble.com/content-on-declarative-ui/ • http://intelligiblebabble.com/compose-from-first-principles/ • #compose channel at https://kotlinlang.slack.com/

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@ragunathjawahar Twitter / Medium / GitHub end;