Merge branch 'smartherd:master' into master

Author: xlogix

README.md

@@ -62,9 +62,21 @@ Learn Kotlin Programming, its basics and Fundamentals from scratch. Follow [this
 11. Sorting and Filtering
     - "filter" function
     - "map" function
-    - Predicates
-12. Conclusion 
+    - Predicates: all, any, find, count. 
+12. Kotlin NULL Safety
+    - Safe call
+    - with Let
+    - Elvis
+    - Lateinit keyword
+    - Lazy delegation and 'lateinit' vs. 'lazy'
+13. Scope Functions
+    - with
+    - apply
+    - let
+    - also
+    - run
+13. Conclusion 
 
 ## Authors 
 
-* **Team Smartherd** 
+* **Sriyank Siddhartha** 

src/1_hello_world.kt renamed to src/01_hello_world.kt

@@ -16,4 +16,4 @@ class Rectangle {
 
     var length: Int = 0
     var breadth: Int = 0
-}
+}

src/2_explore_first_app.kt renamed to src/02_explore_first_app.kt

@@ -0,0 +1,23 @@
+class Person {
+    var name: String = "Sriyank Siddhartha"
+    var age: Int = 26
+}
+
+fun main() {
+
+    /** Scope Function: 'with'
+        Property 1: Refer to context object by using 'this'
+        Property 2: The return value is the 'lambda result'  */
+
+    val person = Person()
+
+    val bio: String = with(person) {
+        println(name)
+        println(age)
+        age + 5
+        "He is a freak who loves to teach in his own way" // will be returned and stored in 'bio' String variable
+    }
+
+//    println("Age after five years is $ageAfterFiveYears")
+    println(bio)
+}

src/3_comments.kt renamed to src/03_comments.kt

@@ -0,0 +1,27 @@
+class Person {
+    var name: String = ""
+    var age: Int = 0
+}
+
+fun main() {
+
+    /** Scope Function: 'apply'
+    Property 1: Refer to context object by using 'this'
+    Property 2: The return value is the 'context object'  */
+
+    val person = Person().apply {
+        name = "Sriyank Siddhartha"
+        age = 26
+    }
+
+    with(person) {
+        println(name)       // prints   Sriyank Siddhartha
+        println(age)        // prints   26 
+    }
+
+    // Perform some other operations on 'person' object
+    person.also {
+        it.name = "Shreks from Smartherd"
+        println("New name: ${it.name}")     // prints   New name: Shreks from Smartherd
+    }
+}

src/4_variables_data_types.kt renamed to src/04_variables_data_types.kt

@@ -0,0 +1,26 @@
+
+
+fun main() {
+
+    /** Scope Function: 'also'              'ALSO PERFORM THE FOLLOWING EXTRA OPERATION'
+    Property 1: Refer to context object by using 'it'
+    Property 2: The return value is the 'context object'  */
+
+    // Initialise numbersList 
+    val numbersList: MutableList<Int> = mutableListOf(1, 2, 3)
+
+    // Some other code... may be a function call or program to swap numbers (doesn't matter what code)
+
+    // Operations on the 'numbersList'
+    val duplicateNumbers = numbersList.also {
+        println("The list elements are: $it")
+        it.add(4)
+        println("The list elements after adding an element: $it")
+        it.remove(2)
+        println("The list elements after removing an element: $it")
+    }
+
+    // duplicateNumbers will be same as numbersList
+    println("Original numbers: $numbersList")
+    println("Duplicate numbers: $duplicateNumbers")
+}

src/5_kotlin_basics.kt renamed to src/05_kotlin_basics.kt

@@ -0,0 +1,20 @@
+
+fun main() {
+
+    /** Scope Function: 'let'
+    Property 1: Refer to context object by using 'it'
+    Property 2: The return value is the 'lambda result'  */
+
+    // Use 'let' function to avoid NullPointerException
+
+    val name: String? = "Hello"
+
+    // Execute the lambda expression only if the 'name' variable is NOT NULL
+    val stringLength = name?.let {
+        println(it.reversed())
+        println(it.capitalize())
+        it.length       // Will be returned and stored within stringLength variable 
+    }
+
+    println(stringLength)
+}

src/6_Person.kt renamed to src/06_Person.kt

@@ -0,0 +1,26 @@
+
+class Person {
+    var name: String = "Sriyank Siddhartha"
+    var age: Int = 26
+}
+
+fun main() {
+
+    /** Scope Function: 'run'
+    Property 1: Refer to context object by using 'this'
+    Property 2: The return value is the 'lambda result'  */
+
+    // 'run' is combination of 'with' and 'let'
+    // If you want to operate on a Nullable object and avoid NullPointerException then use 'run'
+
+    val person: Person? = Person()
+
+    val bio = person?.run {
+        println(name)
+        println(age)
+        age + 5
+        "He is a freak who loves to teach in his own way"   // will be returned and stored in 'bio' variable
+    }
+
+    println(bio)
+}