added Memento design pattern

README.md

@@ -35,6 +35,7 @@ Content:
     * [Observer](/src/main/kotlin/design_patterns/Observer.kt)
     * [Dependency Injection](/src/main/kotlin/design_patterns/Dependency%20%20Injection.kt)
     * [Adapter](/src/main/kotlin/design_patterns/Adapter.kt)
+    * [Memento](/src/main/kotlin/design_patterns/Memento.kt)
 
 2. package <code>structures</code> - data structure
     * [Binary tree](/src/main/kotlin/structures/BinaryTree.kt)

README_ru.md

@@ -33,6 +33,7 @@
     * [Observer](/src/main/kotlin/design_patterns/Observer.kt)
     * [Dependency Injection](/src/main/kotlin/design_patterns/Dependency%20%20Injection.kt)
     * [Adapter](/src/main/kotlin/design_patterns/Adapter.kt)
+    * [Memento](/src/main/kotlin/design_patterns/Memento.kt)
 
 2. пакет <code>ru.structures</code> - структуры данных
     * [Бинарное дерево](/src/main/kotlin/structures/BinaryTree.kt)

src/main/kotlin/design_patterns/Memento.kt

@@ -0,0 +1,55 @@
+package design_patterns
+
+/**
+ *
+ * pattern: Memento
+ *
+ * allows without violating encapsulation, to fix and save the state of an object
+ * in such a way as to restore it to this state
+ *
+ */
+
+
+class Bundle(val str: String)
+
+/**
+ *
+ * Android system emulating
+ *
+ */
+class AndroidSystem {
+    private var bundle: Bundle = Bundle("")
+
+    fun saveBundle(bundle: Bundle) {
+        this.bundle = bundle
+    }
+
+    fun restoreBundle() = bundle
+}
+
+/**
+ *
+ * TextView is an Android component that draws text on the screen
+ *
+ */
+class TextView1 {
+    private var text: String = ""
+
+    fun setText(text: String) {
+        this.text = text
+    }
+
+    fun text() = text
+
+    fun draw() {
+        println(text)
+    }
+
+    fun onSaveInstanceState(): Bundle {
+        return Bundle(text)
+    }
+
+    fun onRestoreInstanceState(bundle: Bundle) {
+        text = bundle.str
+    }
+}

src/test/kotlin/design_patterns/Memento.kt

@@ -0,0 +1,34 @@
+package design_patterns
+
+import org.junit.Test
+import org.junit.jupiter.api.Assertions
+
+class Memento {
+
+    @Test
+    fun test() {
+        // start Android system
+        val android = AndroidSystem()
+
+        val greetingText = TextView1()
+        greetingText.setText(greeting)
+        greetingText.draw()
+
+        // rotating Android device (recreating Application components)
+        // saving state
+        android.saveBundle(greetingText.onSaveInstanceState())
+
+        // the state of the text was lost, but we saved it
+        greetingText.setText("")
+
+        // Android device has already rotated
+        // restoring state
+        greetingText.onRestoreInstanceState(android.restoreBundle())
+
+        Assertions.assertEquals(greeting, greetingText.text())
+    }
+
+    companion object {
+        private const val greeting = "Hello, World!"
+    }
+}