added pattern Command

src/main/kotlin/design_patterns/Builder.kt

@@ -8,7 +8,13 @@ package design_patterns
  * description: to create an object, an auxiliary class Builder is used, which has methods for changing the fields of our main class.
  */
 
-class Pony {
+
+/**
+ * first variant
+ *
+ */
+
+class Pony1 {
     private val name: String
     private val family: String
     private val cutieMark: String
@@ -48,8 +54,68 @@ class Pony {
                 this.city = city
             }
 
-            fun build() = Pony(name, family, cutieMark, city)
+            fun build() = Pony1(name, family, cutieMark, city)
 
     }
 
+}
+
+/**
+ *
+ * the second variant
+ */
+
+class Pony2 {
+    private var name: String = ""
+    private var family: String = ""
+    private var cutieMark: String = ""
+    private var city: String = ""
+
+    fun name() = name
+    fun family() = family
+    fun cutieMark() = cutieMark
+    fun city() = city
+
+    companion object {
+        fun newBuilder() = Pony2().Builder()
+    }
+
+    inner class Builder {
+
+        fun changeName(name: String) = apply {
+            this@Pony2.name = name
+        }
+
+        fun changeFamily(family: String) = apply {
+            this@Pony2.family = family
+        }
+
+        fun changeCutieMark(cutieMark: String) = apply {
+            this@Pony2.cutieMark = cutieMark
+        }
+
+        fun changeCity(city: String) = apply {
+            this@Pony2.city = city
+        }
+
+        fun build() = this@Pony2
+    }
+
+}
+
+/**
+ *
+ * Kotlin variant with default arguments
+ */
+
+class Pony3(
+    private var name: String = "",
+    private var family: String = "",
+    private var cutieMark: String = "",
+    private var city: String = ""
+) {
+    fun name() = name
+    fun family() = family
+    fun cutieMark() = cutieMark
+    fun city() = city
 }

src/main/kotlin/design_patterns/Command.kt

@@ -0,0 +1,23 @@
+package design_patterns
+
+interface ArithmeticCommand {
+    fun execute(number: Int) : Int
+}
+
+class AddCommand(private val addendum: Int) : ArithmeticCommand {
+    override fun execute(number: Int): Int {
+        return number + addendum
+    }
+}
+
+class MinusCommand(private val subtrahend: Int) : ArithmeticCommand {
+    override fun execute(number: Int): Int {
+        return number - subtrahend
+    }
+}
+
+class MultiCommand(private val coefficient: Int) : ArithmeticCommand {
+    override fun execute(number: Int): Int {
+        return number * coefficient
+    }
+}

src/main/kotlin/other/ReverseArray.kt

@@ -11,8 +11,6 @@ class ReverseArray<T> {
     /**
      * creates and returns a reverse array
      *
-     * @array - array
-     * @return returns the reverse array
      */
     fun compute(array: Array<T>) : Array<T> {
         val newArray = array.copyOf()

src/main/kotlin/other/Sqrt.kt

@@ -3,7 +3,7 @@ package other
 /**
  * Algorithm for finding the square root of a number
  *
- * Wikipedia: https://shorturl.at/pvAQ7
+ * Wikipedia: https://ru.wikipedia.org/wiki/%D0%90%D0%BB%D0%B3%D0%BE%D1%80%D0%B8%D1%82%D0%BC_%D0%BD%D0%B0%D1%85%D0%BE%D0%B6%D0%B4%D0%B5%D0%BD%D0%B8%D1%8F_%D0%BA%D0%BE%D1%80%D0%BD%D1%8F_n-%D0%BD%D0%BE%D0%B9_%D1%81%D1%82%D0%B5%D0%BF%D0%B5%D0%BD%D0%B8
  */
 
 class Sqrt {

src/test/kotlin/design_patterns/BuilderTest.kt

@@ -6,14 +6,14 @@ import org.junit.jupiter.api.Assertions.*
 internal class BuilderTest {
 
     @Test
-    fun test() {
+    fun test_first_variant() {
 
         val name = "Twillight Sparkle"
         val cutieMark = "The magic star"
         val city = "Canterlot"
         val family = "Alicorn"
 
-        val pony = Pony.Builder().changeName(name)
+        val pony = Pony1.Builder().changeName(name)
             .changeCutieMark(cutieMark)
             .changeCity(city)
             .changeFamily(family)
@@ -25,4 +25,41 @@ internal class BuilderTest {
         assertEquals(family, pony.family())
     }
 
+    @Test
+    fun test_the_second_variant() {
+
+        val name = "Twillight Sparkle"
+        val cutieMark = "The magic star"
+        val city = "Canterlot"
+        val family = "Alicorn"
+
+        val pony = Pony2.newBuilder().changeName(name)
+            .changeCutieMark(cutieMark)
+            .changeCity(city)
+            .changeFamily(family)
+            .build()
+
+        assertEquals(name, pony.name())
+        assertEquals(cutieMark, pony.cutieMark())
+        assertEquals(city, pony.city())
+        assertEquals(family, pony.family())
+    }
+
+    @Test
+    fun test_third_variant() {
+
+        val name = "Twillight Sparkle"
+        val city = "Canterlot"
+        val family = "Alicorn"
+
+        val pony = Pony3(name, family, city = city)
+
+        assertEquals(name, pony.name())
+        assertEquals("", pony.cutieMark())
+        assertEquals(city, pony.city())
+        assertEquals(family, pony.family())
+    }
+
+
+
 }

src/test/kotlin/design_patterns/Command.kt

@@ -0,0 +1,60 @@
+package design_patterns
+
+import org.junit.Test
+import org.junit.jupiter.api.Assertions
+
+internal class Command {
+
+    @Test
+    fun test_1() {
+        val commands = listOf(
+            AddCommand(10),
+            AddCommand(20),
+            MultiCommand(2),
+            MinusCommand(10)
+        )
+
+        var actual = 0
+        commands.forEach { command ->
+            actual = command.execute(actual)
+        }
+
+        Assertions.assertEquals(50, actual)
+    }
+
+    @Test
+    fun test_2() {
+        val commands = listOf(
+            MultiCommand(2),
+            MultiCommand(2),
+            MultiCommand(2),
+            MultiCommand(2),
+            MinusCommand(100),
+            MultiCommand(-1)
+        )
+
+        var actual = 1
+        commands.forEach { command ->
+            actual = command.execute(actual)
+        }
+
+        Assertions.assertEquals(84, actual)
+    }
+
+    @Test
+    fun test_3() {
+        val commands = listOf(
+            AddCommand(-1),
+            MinusCommand(1000),
+            MultiCommand(-2)
+        )
+
+        var actual = 1
+        commands.forEach { command ->
+            actual = command.execute(actual)
+        }
+
+        Assertions.assertEquals(2000, actual)
+    }
+
+}