From 438b3ed6c2b8bbc2015f896ac3d388ba88ca76f4 Mon Sep 17 00:00:00 2001
From: Sander Ploegsma <sanderploegsma@gmail.com>
Date: Thu, 5 Oct 2023 09:04:53 +0200
Subject: [PATCH] Simplify concept about if-statements (#2508)

* Deprecate concept exercise `blackjack`

* Rename concept to `if-else-statements`

* Remove `if` statements from `numbers` concept

* Remove introduction.md.tpl from `blackjack`

* Add if-else-statements concept to cars-assemble
---
 concepts/conditionals-if/.meta/config.json    |  7 --
 concepts/conditionals-if/about.md             | 69 -------------
 concepts/conditionals-if/introduction.md      | 50 ----------
 concepts/conditionals-if/links.json           | 26 -----
 concepts/if-else-statements/.meta/config.json |  5 +
 concepts/if-else-statements/about.md          | 62 ++++++++++++
 concepts/if-else-statements/introduction.md   | 60 ++++++++++++
 concepts/if-else-statements/links.json        | 10 ++
 concepts/numbers/.meta/config.json            |  6 +-
 concepts/numbers/about.md                     | 14 ---
 concepts/numbers/introduction.md              | 16 ----
 config.json                                   | 96 +++++++++----------
 .../blackjack/.docs/introduction.md.tpl       |  3 -
 .../cars-assemble/.docs/introduction.md       | 65 +++++++++++--
 .../cars-assemble/.docs/introduction.md.tpl   |  2 +
 .../concept/cars-assemble/.meta/design.md     |  3 +-
 16 files changed, 242 insertions(+), 252 deletions(-)
 delete mode 100644 concepts/conditionals-if/.meta/config.json
 delete mode 100644 concepts/conditionals-if/about.md
 delete mode 100644 concepts/conditionals-if/introduction.md
 delete mode 100644 concepts/conditionals-if/links.json
 create mode 100644 concepts/if-else-statements/.meta/config.json
 create mode 100644 concepts/if-else-statements/about.md
 create mode 100644 concepts/if-else-statements/introduction.md
 create mode 100644 concepts/if-else-statements/links.json
 delete mode 100644 exercises/concept/blackjack/.docs/introduction.md.tpl

diff --git a/concepts/conditionals-if/.meta/config.json b/concepts/conditionals-if/.meta/config.json
deleted file mode 100644
index fd0cc4d7a..000000000
--- a/concepts/conditionals-if/.meta/config.json
+++ /dev/null
@@ -1,7 +0,0 @@
-{
-  "blurb": "Java supports various logical operations and conditionals like the if statement.",
-  "authors": [
-    "TalesDias"
-  ],
-  "contributors": []
-}
diff --git a/concepts/conditionals-if/about.md b/concepts/conditionals-if/about.md
deleted file mode 100644
index e67f6e3dc..000000000
--- a/concepts/conditionals-if/about.md
+++ /dev/null
@@ -1,69 +0,0 @@
-# About
-
-## Logical Operators
-
-Java supports three [logical operators][logical-operators] `&&` (AND), `||` (OR), and `!` (NOT).
-
-## If statement
-
-The underlying type of any conditional operation is the `boolean` type, which can have the value of `true` or `false`. Conditionals are often used as flow control mechanisms to check for various conditions. For checking a particular case an [`if` statement][if-statement] can be used, which executes its code if the underlying condition is `true` like this:
-
-```java
-int val;
-
-if(val == 9) {
-    // conditional code
-}
-```
-
-In scenarios involving more than one case many `if` statements can be chained together using the `else if` and `else` statements.
-
-```java
-if(val == 10) {
-    // conditional code
-} else if(val == 17) {
-    // conditional code
-} else {
-    // executes when val is different from 10 and 17
-}
-```
-
-## Switch statement
-
-Java also provides a [`switch` statement][switch-statement] for scenarios with multiple options. It can be used to switch on a variable's content as a replacement for simple `if ... else if` statements. A switch statement can have a `default` case which is executed if no other case applies.
-
-In Java you can't use any type as the value in a `switch`, only integer and enumerated data types, plus the `String` class are allowed.
-
-If there are three or more cases in a single `if` (e.g. `if ... else if ... else`), it should be replaced by a `switch` statement. A `switch` with a single case should be replaced by an `if` statement.
-
-```java
-int val;
-
-// switch statement on variable content
-switch(val) {
-    case 1:
-        // conditional code
-        break;
-    case 2: case 3: case 4:
-        // conditional code
-        break;
-    default:
-        // if all cases fail
-        break;
-}
-```
-
-    Note: Make sure the expression in the switch statement is not null, otherwise a NullPointerException will be thrown
-
-To learn more about this topic it is recommended to check these sources:
-
-- [A refresh of Ternary operators][example-ternary]
-- [If/Else detailed with flowcharts][example-ifelse-flowcharts]
-- [Switch examples][example-switch]
-
-[logical-operators]: https://docs.oracle.com/javase/tutorial/java/nutsandbolts/op2.html
-[if-statement]: https://docs.oracle.com/javase/tutorial/java/nutsandbolts/if.html
-[switch-statement]: https://docs.oracle.com/javase/tutorial/java/nutsandbolts/switch.html
-[example-ifelse-flowcharts]: https://www.javatpoint.com/java-if-else
-[example-ternary]: https://www.programiz.com/java-programming/ternary-operator
-[example-switch]: https://www.geeksforgeeks.org/switch-statement-in-java/
diff --git a/concepts/conditionals-if/introduction.md b/concepts/conditionals-if/introduction.md
deleted file mode 100644
index 3011f35f8..000000000
--- a/concepts/conditionals-if/introduction.md
+++ /dev/null
@@ -1,50 +0,0 @@
-# Introduction
-
-## Logical Operators
-
-Java supports the three logical operators `&&` (AND), `||` (OR), and `!` (NOT).
-
-## If statement
-
-The underlying type of any conditional operation is the `boolean` type, which can have the value of `true` or `false`. Conditionals are often used as flow control mechanisms to check for various conditions. For checking a particular case an `if` statement can be used, which executes its code if the underlying condition is `true` like this:
-
-```java
-int val;
-
-if(val == 9) {
-    // conditional code
-}
-```
-
-In scenarios involving more than one case many `if` statements can be chained together using the `else if` and `else` statements.
-
-```java
-if(val == 10) {
-    // conditional code
-} else if(val == 17) {
-    // conditional code
-} else {
-    // executes when val is different from 10 and 17
-}
-```
-
-## Switch statement
-
-Java also provides a `switch` statement for scenarios with multiple options.
-
-```java
-int val;
-
-// switch statement on variable content
-switch(val) {
-    case 1:
-        // conditional code
-        break;
-    case 2: case 3: case 4:
-        // conditional code
-        break;
-    default:
-        // if all cases fail
-        break;
-}
-```
diff --git a/concepts/conditionals-if/links.json b/concepts/conditionals-if/links.json
deleted file mode 100644
index 0ba39adb6..000000000
--- a/concepts/conditionals-if/links.json
+++ /dev/null
@@ -1,26 +0,0 @@
-[
-  {
-    "url": "https://docs.oracle.com/javase/tutorial/java/nutsandbolts/op2.html",
-    "description": "logical-operators"
-  },
-  {
-    "url": "https://docs.oracle.com/javase/tutorial/java/nutsandbolts/if.html",
-    "description": "if-statement"
-  },
-  {
-    "url": "https://docs.oracle.com/javase/tutorial/java/nutsandbolts/switch.html",
-    "description": "switch-statement"
-  },
-  {
-    "url": "https://www.programiz.com/java-programming/ternary-operator",
-    "description": "example-ternary"
-  },
-  {
-    "url": "https://www.javatpoint.com/java-if-else",
-    "description": "example-ifelse-flowcharts"
-  },
-  {
-    "url": "https://www.geeksforgeeks.org/switch-statement-in-java/",
-    "description": "example-switch"
-  }
-]
diff --git a/concepts/if-else-statements/.meta/config.json b/concepts/if-else-statements/.meta/config.json
new file mode 100644
index 000000000..5ab956b98
--- /dev/null
+++ b/concepts/if-else-statements/.meta/config.json
@@ -0,0 +1,5 @@
+{
+  "blurb": "If-else statements can be used to perform conditional logic.",
+  "authors": ["TalesDias", "sanderploegsma"],
+  "contributors": []
+}
diff --git a/concepts/if-else-statements/about.md b/concepts/if-else-statements/about.md
new file mode 100644
index 000000000..ab9a63ed6
--- /dev/null
+++ b/concepts/if-else-statements/about.md
@@ -0,0 +1,62 @@
+# About
+
+## The _if-then_ statement
+
+The most basic control flow statement in Java is the [_if-then_ statement][if-statement].
+This statement is used to only execute a section of code if a particular condition is `true`.
+An _if-then_ statement is defined using the `if` clause:
+
+```java
+class Car {
+    void drive() {
+        // the "if" clause: the car needs to have fuel left to drive
+        if (fuel > 0) {
+            // the "then" clause: the car drives, consuming fuel
+            fuel--;
+        }
+    }
+}
+```
+
+In the above example, if the car is out of fuel, calling the `Car.drive` method will do nothing.
+
+## The _if-then-else_ statement
+
+The _if-then-else_ statement provides an alternative path of execution for when the condition in the `if` clause evaluates to `false`.
+This alternative path of execution follows an `if` clause and is defined using the `else` clause:
+
+```java
+class Car {
+    void drive() {
+        if (fuel > 0) {
+            fuel--;
+        } else {
+            stop();
+        }
+    }
+}
+```
+
+In the above example, if the car is out of fuel, calling the `Car.drive` method will call another method to stop the car.
+
+The _if-then-else_ statement also supports multiple conditions by using the `else if` clause:
+
+```java
+class Car {
+    void drive() {
+        if (fuel > 5) {
+            fuel--;
+        } else if (fuel > 0) {
+            turnOnFuelLight();
+            fuel--;
+        } else {
+            stop();
+        }
+    }
+}
+```
+
+In the above example, driving the car when the fuel is less then or equal to `5` will drive the car, but it will turn on the fuel light.
+When the fuel reaches `0`, the car will stop driving.
+
+[if-statement]: https://docs.oracle.com/javase/tutorial/java/nutsandbolts/if.html
diff --git a/concepts/if-else-statements/introduction.md b/concepts/if-else-statements/introduction.md
new file mode 100644
index 000000000..4e6d3dc32
--- /dev/null
+++ b/concepts/if-else-statements/introduction.md
@@ -0,0 +1,60 @@
+# Introduction
+
+## The _if-then_ statement
+
+The most basic control flow statement in Java is the _if-then_ statement.
+This statement is used to only execute a section of code if a particular condition is `true`.
+An _if-then_ statement is defined using the `if` clause:
+
+```java
+class Car {
+    void drive() {
+        // the "if" clause: the car needs to have fuel left to drive
+        if (fuel > 0) {
+            // the "then" clause: the car drives, consuming fuel
+            fuel--;
+        }
+    }
+}
+```
+
+In the above example, if the car is out of fuel, calling the `Car.drive` method will do nothing.
+
+## The _if-then-else_ statement
+
+The _if-then-else_ statement provides an alternative path of execution for when the condition in the `if` clause evaluates to `false`.
+This alternative path of execution follows an `if` clause and is defined using the `else` clause:
+
+```java
+class Car {
+    void drive() {
+        if (fuel > 0) {
+            fuel--;
+        } else {
+            stop();
+        }
+    }
+}
+```
+
+In the above example, if the car is out of fuel, calling the `Car.drive` method will call another method to stop the car.
+
+The _if-then-else_ statement also supports multiple conditions by using the `else if` clause:
+
+```java
+class Car {
+    void drive() {
+        if (fuel > 5) {
+            fuel--;
+        } else if (fuel > 0) {
+            turnOnFuelLight();
+            fuel--;
+        } else {
+            stop();
+        }
+    }
+}
+```
+
+In the above example, driving the car when the fuel is less then or equal to `5` will drive the car, but it will turn on the fuel light.
+When the fuel reaches `0`, the car will stop driving.
diff --git a/concepts/if-else-statements/links.json b/concepts/if-else-statements/links.json
new file mode 100644
index 000000000..0f138a23f
--- /dev/null
+++ b/concepts/if-else-statements/links.json
@@ -0,0 +1,10 @@
+[
+  {
+    "url": "https://docs.oracle.com/javase/tutorial/java/nutsandbolts/if.html",
+    "description": "Java tutorial on if-then-else statements"
+  },
+  {
+    "url": "https://www.javatpoint.com/java-if-else",
+    "description": "Example if-then-else statements with flow charts"
+  }
+]
diff --git a/concepts/numbers/.meta/config.json b/concepts/numbers/.meta/config.json
index fdffc23f4..506871c4f 100644
--- a/concepts/numbers/.meta/config.json
+++ b/concepts/numbers/.meta/config.json
@@ -1,7 +1,5 @@
 {
   "blurb": "Java includes various numeric types including integer and floating-point numbers.",
-  "authors": [
-    "TalesDias"
-  ],
-  "contributors": []
+  "authors": ["TalesDias"],
+  "contributors": ["sanderploegsma"]
 }
diff --git a/concepts/numbers/about.md b/concepts/numbers/about.md
index 3ef210de8..53e057db4 100644
--- a/concepts/numbers/about.md
+++ b/concepts/numbers/about.md
@@ -62,20 +62,6 @@ double fromInt = i;
 int fromDouble = (int)d;
 ```
 
-An `if` statement can be used to conditionally execute code. The condition of an `if` statement must be of type `boolean`. Java has no concept of _truthy_ values.
-
-```java
-int x = 6;
-
-if (x == 5){
-    // Execute logic if x equals 5
-} else if (x > 7){
-    // Execute logic if x greater than 7
-} else{
-    // Execute logic in all other cases
-}
-```
-
 [arithmetic-operators]: https://docs.oracle.com/javase/tutorial/java/nutsandbolts/op1.html
 [comparison-operators]: https://docs.oracle.com/javase/tutorial/java/nutsandbolts/op2.html
 [type-casting]: https://www.programiz.com/java-programming/typecasting
diff --git a/concepts/numbers/introduction.md b/concepts/numbers/introduction.md
index d68887ddb..352a45eb5 100644
--- a/concepts/numbers/introduction.md
+++ b/concepts/numbers/introduction.md
@@ -15,19 +15,3 @@ Java has two types of numeric conversions:
 2. Explicit conversions: data could be lost and additional syntax in the form of a _cast_ is required.
 
 As an `int` has less precision than a `double`, converting from an `int` to a `double` is safe and is thus an implicit conversion. However, converting from a `double` to an `int` could mean losing data, so that requires an explicit conversion.
-
-In this exercise you must conditionally execute logic. The most common way to do this in Java is by using an `if/else` statement:
-
-```java
-int x = 6;
-
-if (x == 5) {
-    // Execute logic if x equals 5
-} else if (x > 7) {
-    // Execute logic if x greater than 7
-} else {
-    // Execute logic in all other cases
-}
-```
-
-The condition of an `if` statement must be of type `boolean`. 
diff --git a/config.json b/config.json
index b655cabf1..23829da5b 100644
--- a/config.json
+++ b/config.json
@@ -66,7 +66,7 @@
           "foreach-loops"
         ],
         "prerequisites": [
-          "conditionals-if"
+          "if-else-statements"
         ],
         "status": "active"
       },
@@ -93,7 +93,7 @@
           "exceptions"
         ],
         "prerequisites": [
-          "conditionals-if",
+          "if-else-statements",
           "switch-statement"
         ],
         "status": "beta"
@@ -118,7 +118,7 @@
           "classes"
         ],
         "prerequisites": [
-          "conditionals-if",
+          "if-else-statements",
           "numbers",
           "strings"
         ],
@@ -128,13 +128,9 @@
         "slug": "blackjack",
         "name": "Play Your Cards!",
         "uuid": "43b8f2e3-99e9-49cc-a897-d66f0f26670d",
-        "concepts": [
-          "conditionals-if"
-        ],
-        "prerequisites": [
-          "booleans"
-        ],
-        "status": "active"
+        "concepts": [],
+        "prerequisites": [],
+        "status": "deprecated"
       },
       {
         "slug": "need-for-speed",
@@ -166,12 +162,8 @@
         "slug": "cars-assemble",
         "name": "Cars, Assemble!",
         "uuid": "3f451c6b-04e2-4b08-8bb0-7dcd2ec5b8f4",
-        "concepts": [
-          "numbers"
-        ],
-        "prerequisites": [
-          "conditionals-if"
-        ],
+        "concepts": ["if-else-statements", "numbers"],
+        "prerequisites": ["booleans"],
         "status": "active"
       },
       {
@@ -194,7 +186,7 @@
           "ternary-operators"
         ],
         "prerequisites": [
-          "conditionals-if",
+          "if-else-statements",
           "numbers"
         ],
         "status": "active"
@@ -250,7 +242,7 @@
         "uuid": "74515d45-565b-4be2-96c4-77e58efa9257",
         "practices": [
           "strings",
-          "conditionals-if"
+          "if-else-statements"
         ],
         "prerequisites": [
           "basics"
@@ -348,7 +340,7 @@
         ],
         "prerequisites": [
           "numbers",
-          "conditionals-if"          
+          "if-else-statements"          
         ],
         "difficulty": 4
       },
@@ -361,7 +353,7 @@
         ],
         "prerequisites": [
           "strings",
-          "conditionals-if",
+          "if-else-statements",
           "for-loops"
         ],
         "difficulty": 4
@@ -388,7 +380,7 @@
           "lists"
         ],
         "prerequisites": [
-          "conditionals-if",
+          "if-else-statements",
           "for-loops",
           "classes"
         ],
@@ -429,7 +421,7 @@
           "lists"
         ],
         "prerequisites": [
-          "conditionals-if",
+          "if-else-statements",
           "classes"
         ],
         "difficulty": 6
@@ -470,12 +462,12 @@
         "name": "Raindrops",
         "uuid": "d916e4f8-fda1-41c0-ab24-79e8fc3f1272",
         "practices": [
-          "conditionals-if",
+          "if-else-statements",
           "numbers",
           "strings"
         ],
         "prerequisites": [
-          "conditionals-if",
+          "if-else-statements",
           "numbers",
           "strings"
         ],
@@ -486,12 +478,12 @@
         "name": "Isogram",
         "uuid": "c3e89c7c-3a8a-4ddc-b653-9b0ff9e1d7d8",
         "practices": [
-          "conditionals-if",
+          "if-else-statements",
           "for-loops",
           "strings"
         ],
         "prerequisites": [
-          "conditionals-if",
+          "if-else-statements",
           "for-loops",
           "strings"
         ],
@@ -519,13 +511,13 @@
         "uuid": "fb10dc2f-0ba1-44b6-8365-5e48e86d1283",
         "practices": [
           "arrays",
-          "conditionals-if",
+          "if-else-statements",
           "lists",
           "for-loops"
         ],
         "prerequisites": [
           "arrays",
-          "conditionals-if",
+          "if-else-statements",
           "lists",
           "for-loops"
         ],
@@ -549,7 +541,7 @@
         "name": "Darts",
         "uuid": "4d400a44-b190-4a0c-affb-99fad8ea18da",
         "practices": [
-          "conditionals-if",
+          "if-else-statements",
           "constructors"
         ],
         "prerequisites": [
@@ -579,7 +571,7 @@
           "numbers"
         ],
         "prerequisites": [
-          "conditionals-if",
+          "if-else-statements",
           "for-loops"
         ],
         "difficulty": 2
@@ -678,7 +670,7 @@
         "name": "Bob",
         "uuid": "34cd328c-cd96-492b-abd4-2b8716cdcd9a",
         "practices": [
-          "conditionals-if"
+          "if-else-statements"
         ],
         "prerequisites": [
           "strings",
@@ -783,7 +775,7 @@
           "lists"
         ],
         "prerequisites": [
-          "conditionals-if",
+          "if-else-statements",
           "classes"
         ],
         "difficulty": 5
@@ -796,7 +788,7 @@
           "strings"
         ],
         "prerequisites": [
-          "conditionals-if",
+          "if-else-statements",
           "for-loops",
           "classes"
         ],
@@ -811,7 +803,7 @@
         ],
         "prerequisites": [
           "chars",
-          "conditionals-if",
+          "if-else-statements",
           "classes"
         ],
         "difficulty": 5
@@ -924,7 +916,7 @@
         "topics": [
           "arrays",
           "classes",
-          "conditionals-if",
+          "if-else-statements",
           "games",
           "matrices"
         ]
@@ -948,7 +940,7 @@
         "name": "Go Counting",
         "uuid": "2e760ae2-fadd-4d31-9639-c4554e2826e9",
         "practices": [
-          "conditionals-if",
+          "if-else-statements",
           "for-loops",
           "enums"
         ],
@@ -965,7 +957,7 @@
         "prerequisites": [],
         "difficulty": 7,
         "topics": [
-          "conditionals-if",
+          "if-else-statements",
           "pattern_matching",
           "refactoring",
           "strings"
@@ -1050,7 +1042,7 @@
         "difficulty": 4,
         "topics": [
           "arrays",
-          "conditionals-if",
+          "if-else-statements",
           "integers",
           "loops",
           "math"
@@ -1065,7 +1057,7 @@
         "difficulty": 4,
         "topics": [
           "bitwise_operations",
-          "conditionals-if",
+          "if-else-statements",
           "exception_handling",
           "lists",
           "loops",
@@ -1080,7 +1072,7 @@
         "prerequisites": [],
         "difficulty": 6,
         "topics": [
-          "conditionals-if",
+          "if-else-statements",
           "logic"
         ]
       },
@@ -1218,7 +1210,7 @@
         "prerequisites": [],
         "difficulty": 4,
         "topics": [
-          "conditionals-if",
+          "if-else-statements",
           "exception_handling",
           "integers",
           "math",
@@ -1262,7 +1254,7 @@
         "difficulty": 5,
         "topics": [
           "arrays",
-          "conditionals-if",
+          "if-else-statements",
           "integers",
           "lists",
           "loops",
@@ -1278,7 +1270,7 @@
         "difficulty": 7,
         "topics": [
           "algorithms",
-          "conditionals-if",
+          "if-else-statements",
           "loops"
         ]
       },
@@ -1370,7 +1362,7 @@
         "prerequisites": [],
         "difficulty": 6,
         "topics": [
-          "conditionals-if",
+          "if-else-statements",
           "loops",
           "strings"
         ]
@@ -1414,7 +1406,7 @@
         "difficulty": 6,
         "topics": [
           "arrays",
-          "conditionals-if",
+          "if-else-statements",
           "exception_handling",
           "integers",
           "loops",
@@ -1456,7 +1448,7 @@
         "prerequisites": [],
         "difficulty": 8,
         "topics": [
-          "conditionals-if",
+          "if-else-statements",
           "integers",
           "lists",
           "loops",
@@ -1525,7 +1517,7 @@
         "prerequisites": [],
         "difficulty": 6,
         "topics": [
-          "conditionals-if",
+          "if-else-statements",
           "lists",
           "maps",
           "sorting",
@@ -1896,7 +1888,7 @@
         "prerequisites": [],
         "difficulty": 3,
         "topics": [
-          "conditionals-if",
+          "if-else-statements",
           "floating_point_numbers"
         ]
       },
@@ -1921,7 +1913,7 @@
         "prerequisites": [
             "strings",
             "chars",
-            "conditionals-if",
+            "if-else-statements",
             "lists",
             "for-loops"
         ],
@@ -1934,7 +1926,7 @@
         "practices": [],
         "prerequisites": [
           "strings",
-          "conditionals-if",
+          "if-else-statements",
           "lists",
           "for-loops"
         ],
@@ -1995,8 +1987,8 @@
     },
     {
       "uuid": "4ce7cdbb-4ff3-4988-89db-8fbcef380500",
-      "slug": "conditionals-if",
-      "name": "Conditionals If"
+      "slug": "if-else-statements",
+      "name": "If-Else Statements"
     },
     {
       "uuid": "e552c05c-6360-4b2f-a438-7ec7e855c0f5",
diff --git a/exercises/concept/blackjack/.docs/introduction.md.tpl b/exercises/concept/blackjack/.docs/introduction.md.tpl
deleted file mode 100644
index bca061f4c..000000000
--- a/exercises/concept/blackjack/.docs/introduction.md.tpl
+++ /dev/null
@@ -1,3 +0,0 @@
-# Introduction
-
-%{concept:conditionals-if}
diff --git a/exercises/concept/cars-assemble/.docs/introduction.md b/exercises/concept/cars-assemble/.docs/introduction.md
index c05cfe01f..50fc496e1 100644
--- a/exercises/concept/cars-assemble/.docs/introduction.md
+++ b/exercises/concept/cars-assemble/.docs/introduction.md
@@ -18,18 +18,63 @@ Java has two types of numeric conversions:
 
 As an `int` has less precision than a `double`, converting from an `int` to a `double` is safe and is thus an implicit conversion. However, converting from a `double` to an `int` could mean losing data, so that requires an explicit conversion.
 
-In this exercise you must conditionally execute logic. The most common way to do this in Java is by using an `if/else` statement:
+## If-Else Statements
+
+### The _if-then_ statement
+
+The most basic control flow statement in Java is the _if-then_ statement.
+This statement is used to only execute a section of code if a particular condition is `true`.
+An _if-then_ statement is defined using the `if` clause:
+
+```java
+class Car {
+    void drive() {
+        // the "if" clause: the car needs to have fuel left to drive
+        if (fuel > 0) {
+            // the "then" clause: the car drives, consuming fuel
+            fuel--;
+        }
+    }
+}
+```
+
+In the above example, if the car is out of fuel, calling the `Car.drive` method will do nothing.
+
+### The _if-then-else_ statement
+
+The _if-then-else_ statement provides an alternative path of execution for when the condition in the `if` clause evaluates to `false`.
+This alternative path of execution follows an `if` clause and is defined using the `else` clause:
+
+```java
+class Car {
+    void drive() {
+        if (fuel > 0) {
+            fuel--;
+        } else {
+            stop();
+        }
+    }
+}
+```
+
+In the above example, if the car is out of fuel, calling the `Car.drive` method will call another method to stop the car.
+
+The _if-then-else_ statement also supports multiple conditions by using the `else if` clause:
 
 ```java
-int x = 6;
-
-if (x == 5) {
-    // Execute logic if x equals 5
-} else if (x > 7) {
-    // Execute logic if x greater than 7
-} else {
-    // Execute logic in all other cases
+class Car {
+    void drive() {
+        if (fuel > 5) {
+            fuel--;
+        } else if (fuel > 0) {
+            turnOnFuelLight();
+            fuel--;
+        } else {
+            stop();
+        }
+    }
 }
 ```
 
-The condition of an `if` statement must be of type `boolean`.
+In the above example, driving the car when the fuel is less then or equal to `5` will drive the car, but it will turn on the fuel light.
+When the fuel reaches `0`, the car will stop driving.
diff --git a/exercises/concept/cars-assemble/.docs/introduction.md.tpl b/exercises/concept/cars-assemble/.docs/introduction.md.tpl
index ce74d2829..0c29a1a96 100644
--- a/exercises/concept/cars-assemble/.docs/introduction.md.tpl
+++ b/exercises/concept/cars-assemble/.docs/introduction.md.tpl
@@ -1,3 +1,5 @@
 # Introduction
 
 %{concept:numbers}
+
+%{concept:if-else-statements}
diff --git a/exercises/concept/cars-assemble/.meta/design.md b/exercises/concept/cars-assemble/.meta/design.md
index 5c1c20972..8d54df485 100644
--- a/exercises/concept/cars-assemble/.meta/design.md
+++ b/exercises/concept/cars-assemble/.meta/design.md
@@ -17,10 +17,11 @@
 ## Concepts
 
 - `numbers`: know of the existence of the two most commonly used number types, `int` and `double`; understand that the former represents whole numbers, and the latter floating-point numbers; know of basic operators such as multiplication, comparison and equality; know how to convert from one numeric type to another; know what implicit and explicit conversions are.
-- `conditionals`: know how to conditionally execute code using an `if` statement.
+- `if-else-statements`: know how to conditionally execute code using an `if` statement.
 
 ## Prerequisites
 
 This exercise's prerequisites Concepts are:
 
 - `basics`: know how to define methods.
+- `booleans`: know how to use boolean operators.