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Commit 1f7cbc4

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evitwilly
committed
added Memento design pattern
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‎README.md

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* [Observer](/src/main/kotlin/design_patterns/Observer.kt)
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* [Dependency Injection](/src/main/kotlin/design_patterns/Dependency%20%20Injection.kt)
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* [Adapter](/src/main/kotlin/design_patterns/Adapter.kt)
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* [Memento](/src/main/kotlin/design_patterns/Memento.kt)
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2. package <code>structures</code> - data structure
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* [Binary tree](/src/main/kotlin/structures/BinaryTree.kt)

‎README_ru.md

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* [Observer](/src/main/kotlin/design_patterns/Observer.kt)
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* [Dependency Injection](/src/main/kotlin/design_patterns/Dependency%20%20Injection.kt)
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* [Adapter](/src/main/kotlin/design_patterns/Adapter.kt)
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* [Memento](/src/main/kotlin/design_patterns/Memento.kt)
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2. пакет <code>ru.structures</code> - структуры данных
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* [Бинарное дерево](/src/main/kotlin/structures/BinaryTree.kt)
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package design_patterns
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/**
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*
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* pattern: Memento
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*
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* allows without violating encapsulation, to fix and save the state of an object
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* in such a way as to restore it to this state
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*
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*/
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class Bundle(val str: String)
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/**
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*
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* Android system emulating
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*
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*/
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class AndroidSystem {
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private var bundle: Bundle = Bundle("")
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fun saveBundle(bundle: Bundle) {
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this.bundle = bundle
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}
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fun restoreBundle() = bundle
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}
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/**
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*
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* TextView is an Android component that draws text on the screen
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*
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*/
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class TextView1 {
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private var text: String = ""
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fun setText(text: String) {
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this.text = text
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}
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fun text() = text
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fun draw() {
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println(text)
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}
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fun onSaveInstanceState(): Bundle {
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return Bundle(text)
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}
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fun onRestoreInstanceState(bundle: Bundle) {
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text = bundle.str
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}
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}
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package design_patterns
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import org.junit.Test
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import org.junit.jupiter.api.Assertions
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class Memento {
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@Test
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fun test() {
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// start Android system
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val android = AndroidSystem()
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val greetingText = TextView1()
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greetingText.setText(greeting)
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greetingText.draw()
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// rotating Android device (recreating Application components)
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// saving state
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android.saveBundle(greetingText.onSaveInstanceState())
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// the state of the text was lost, but we saved it
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greetingText.setText("")
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// Android device has already rotated
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// restoring state
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greetingText.onRestoreInstanceState(android.restoreBundle())
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Assertions.assertEquals(greeting, greetingText.text())
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}
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companion object {
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private const val greeting = "Hello, World!"
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}
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}

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