lesson 4 update

src/main/kotlin/lesson4/Idiom31.kt

@@ -1,13 +1,25 @@
 package lesson4
 
-class Bad{
+
+open class Bad{
     val value: Int
 
     init {
         value = requestValue()
     }
 
-    private fun requestValue(): Int = TODO()
+    open fun requestValue(): Int {
+        doSomethingElse()
+        return 2
+    }
+
+    private fun doSomethingElse(){
+        println(value)
+    }
+}
+
+fun main() {
+    Bad()
 }
 
 

src/main/kotlin/lesson4/idiom27.kt

@@ -6,7 +6,7 @@ import kotlin.random.Random
 fun main() {
     val b = Random.nextBoolean()
     // assign value to an expression
-    val a = if (b) 0 else 1
+    val a = if (b) 0 else 1 // b ? 0 : 1
 
     //Use Try/catch as an exception
     val result = try {
@@ -14,5 +14,6 @@ fun main() {
     } catch (e: NumberFormatException) {
         null //Strongly discouraged in performance-critical code
     }
+    println(result)
 
 }

src/main/kotlin/lesson4/idiom28.kt

@@ -8,4 +8,5 @@ fun main() {
             add(it)
         }
     }
+    println(list)
 }

src/main/kotlin/lesson4/idiom29.kt

@@ -6,7 +6,7 @@ import java.nio.file.Paths
 fun main() {
     val stream = Files.newInputStream(Paths.get("/some/file.txt"))
     // The resource is automatically closed  when leaving the scope
-    stream.buffered().reader().use { reader ->
+    stream.bufferedReader().use { reader ->
         println(reader.readText())
     }
 }

src/main/kotlin/lesson4/idiom30.kt

@@ -1,10 +1,11 @@
 package lesson4
 
+import kotlin.random.Random
+
 interface Factory<T : Any> {
     fun build(str: String): T
 }
 
-
 class IntContainer(val arg: Int) {
     companion object : Factory<IntContainer> {
         override fun build(str: String) = IntContainer(str.toInt())
@@ -21,4 +22,7 @@ fun <T : Any> buildContainer(str: String, factory: Factory<T>): T = factory.buil
 
 fun main() {
     buildContainer("22", IntContainer)
+
+    val random = Random
+    random.nextDouble()
 }

src/main/kotlin/lesson4/idiom32.kt

@@ -4,6 +4,7 @@ class ClassWithALazyProperty{
     //Use lazy delegate for something that should be calculated ones on first call
     val lazyValue by lazy {
         //Do dome heavy logic here
+        22
     }
 }
 

src/main/kotlin/lesson4/idiom33.kt

@@ -31,6 +31,7 @@ inline fun <reified T: Any> List<T>.prettyPrint() = forEach {
 }
 
 /**
- * **WARNING** inline functions are an advanced feature and should be used only for reification or non-local return
+ * **WARNING** inline functions are an advanced feature and should be used only for
+ * reification or non-local return
  * NOT for optimization.
  */

src/main/kotlin/lesson4/idiom34.kt

@@ -3,14 +3,14 @@ package lesson4
 /**
  * Values are boxed. Each call is indirect
  */
-val list: List<Double> = List(20){it.toDouble()}
+val list: List<Double> = List(20) { it.toDouble() }
 
 /**
  * Still boxed
  */
-val genericArray: Array<Double> = Array(20){it.toDouble()}
+val genericArray: Array<Double> = Array(20) { it.toDouble() }
 
 /**
  * Non-boxed
  */
-val specializedArray: DoubleArray = DoubleArray(20){it.toDouble()}
+val specializedArray: DoubleArray = DoubleArray(20) { it.toDouble() }