From f44cc311bd672013c4b230960004fcab7e20dd60 Mon Sep 17 00:00:00 2001
From: Anirban Chatterjee <canirban99@gmail.com>
Date: Sat, 22 Aug 2020 12:30:44 +0200
Subject: [PATCH 1/4] Added aggregate operations

---
 .../kotlin/collections/AggregateOperations.kt | 131 ++++++++++++++++++
 .../AggregateOperationsUnitTest.kt            | 104 ++++++++++++++
 2 files changed, 235 insertions(+)
 create mode 100644 core-kotlin-modules/core-kotlin-collections/src/main/kotlin/com/baeldung/kotlin/collections/AggregateOperations.kt
 create mode 100644 core-kotlin-modules/core-kotlin-collections/src/test/kotlin/com/baeldung/kotlin/collections/AggregateOperationsUnitTest.kt

diff --git a/core-kotlin-modules/core-kotlin-collections/src/main/kotlin/com/baeldung/kotlin/collections/AggregateOperations.kt b/core-kotlin-modules/core-kotlin-collections/src/main/kotlin/com/baeldung/kotlin/collections/AggregateOperations.kt
new file mode 100644
index 0000000000..854190382c
--- /dev/null
+++ b/core-kotlin-modules/core-kotlin-collections/src/main/kotlin/com/baeldung/kotlin/collections/AggregateOperations.kt
@@ -0,0 +1,131 @@
+package com.baeldung.kotlin.collections
+
+class AggregateOperations {
+    private val numbers = listOf(1, 15, 3, 8)
+
+    fun countList(): Int {
+        return numbers.count()
+    }
+
+    fun sumList(): Int {
+        return numbers.sum()
+    }
+
+    fun averageList(): Double {
+        return numbers.average()
+    }
+
+    fun maximumInList(): Int? {
+        return numbers.max()
+    }
+
+    fun minimumInList(): Int? {
+        return numbers.min()
+    }
+
+    fun maximumByList(): Int? {
+        return numbers.maxBy { it % 5 }
+    }
+
+    fun minimumByList(): Int? {
+        return numbers.minBy { it % 5 }
+    }
+
+    fun maximumWithList(): String? {
+        val strings = listOf("Berlin", "Kolkata", "Prague", "Barcelona")
+        return strings.maxWith(compareBy { it.length % 4 })
+    }
+
+    fun minimumWithList(): String? {
+        val strings = listOf("Berlin", "Kolkata", "Prague", "Barcelona")
+        return strings.minWith(compareBy { it.length % 4 })
+    }
+
+    fun sumByList(): Int {
+        return numbers.sumBy { it * 5 }
+    }
+
+    fun sumByDoubleList(): Double {
+        return numbers.sumByDouble { it.toDouble() / 8 }
+    }
+
+    fun foldList(): Int {
+        println("fold operation")
+        val result = numbers.fold(100) { total, it ->
+            println("total = $total, it = $it")
+            total - it
+        }
+        println(result) // ((((100 - 1)-15)-3)-8) = 73
+        return result
+    }
+
+    fun foldRightList(): Int {
+        println("foldRight operation")
+        val result = numbers.foldRight(100) { it, total ->
+            println("total = $total, it = $it")
+            total - it
+        }
+        println(result) // ((((100-8)-3)-15)-1) = 73
+        return result
+    }
+
+    fun foldIndexedList(): Int {
+        println("foldIndexed operation")
+        val result = numbers.foldIndexed(100) { index, total, it ->
+            println("total = $total, it = $it, index = $index")
+            if (index.minus(2) >= 0) total - it else total
+        }
+        println(result) // ((100 - 3)-8) = 89
+        return result
+    }
+
+    fun foldRightIndexedList(): Int {
+        println("foldRightIndexed operation")
+        val result = numbers.foldRightIndexed(100) { index, it, total ->
+            println("total = $total, it = $it, index = $index")
+            if (index.minus(2) >= 0) total - it else total
+        }
+        println(result) // ((100 - 8)-3) = 89
+        return result
+    }
+
+    fun reduceList(): Int {
+        println("reduce operation")
+        val result = numbers.reduce { total, it ->
+            println("total = $total, it = $it")
+            total - it
+        }
+        println(result) // (((1 - 15)-3)-8) = -25
+        return result
+    }
+
+    fun reduceRightList(): Int {
+        println("reduceRight operation")
+        val result = numbers.reduceRight() { it, total ->
+            println("total = $total, it = $it")
+            total - it
+        }
+        println(result) // ((8-3)-15)-1) = -11
+        return result
+    }
+
+    fun reduceIndexedList(): Int {
+        println("reduceIndexed operation")
+        val result = numbers.reduceIndexed { index, total, it ->
+            println("total = $total, it = $it, index = $index")
+            if (index.minus(2) >= 0) total - it else total
+        }
+        println(result) // ((1-3)-8) = -10
+        return result
+    }
+
+    fun reduceRightIndexedList(): Int {
+        println("reduceRightIndexed operation")
+        val result = numbers.reduceRightIndexed { index, it, total ->
+            println("total = $total, it = $it, index = $index")
+            if (index.minus(2) >= 0) total - it else total
+        }
+        println(result) // ((8-3) = 5
+        return result
+    }
+}
diff --git a/core-kotlin-modules/core-kotlin-collections/src/test/kotlin/com/baeldung/kotlin/collections/AggregateOperationsUnitTest.kt b/core-kotlin-modules/core-kotlin-collections/src/test/kotlin/com/baeldung/kotlin/collections/AggregateOperationsUnitTest.kt
new file mode 100644
index 0000000000..1fb26760fc
--- /dev/null
+++ b/core-kotlin-modules/core-kotlin-collections/src/test/kotlin/com/baeldung/kotlin/collections/AggregateOperationsUnitTest.kt
@@ -0,0 +1,104 @@
+package com.baeldung.kotlin.collections
+
+import org.junit.jupiter.api.Test
+import kotlin.test.assertEquals
+
+class AggregateOperationsUnitTest {
+
+    private val classUnderTest: AggregateOperations = AggregateOperations()
+
+    @Test
+    fun whenCountOfList_thenReturnsValue() {
+        assertEquals(4, classUnderTest.countList())
+    }
+
+    @Test
+    fun whenSumOfList_thenReturnsTotalValue() {
+        assertEquals(27, classUnderTest.sumList())
+    }
+
+    @Test
+    fun whenAverageOfList_thenReturnsValue() {
+        assertEquals(6.75, classUnderTest.averageList())
+    }
+
+    @Test
+    fun whenMaximumOfList_thenReturnsMaximumValue() {
+        assertEquals(15, classUnderTest.maximumInList())
+    }
+
+    @Test
+    fun whenMinimumOfList_thenReturnsMinimumValue() {
+        assertEquals(1, classUnderTest.minimumInList())
+    }
+
+    @Test
+    fun whenMaxByList_thenReturnsLargestValue() {
+        assertEquals(3, classUnderTest.maximumByList())
+    }
+
+    @Test
+    fun whenMinByList_thenReturnsSmallestValue() {
+        assertEquals(15, classUnderTest.minimumByList())
+    }
+
+    @Test
+    fun whenMaxWithList_thenReturnsLargestValue(){
+        assertEquals("Kolkata", classUnderTest.maximumWithList())
+    }
+
+    @Test
+    fun whenMinWithList_thenReturnsSmallestValue(){
+        assertEquals("Barcelona", classUnderTest.minimumWithList())
+    }
+
+    @Test
+    fun whenSumByList_thenReturnsIntegerValue(){
+        assertEquals(135, classUnderTest.sumByList())
+    }
+
+    @Test
+    fun whenSumByDoubleList_thenReturnsDoubleValue(){
+        assertEquals(3.375, classUnderTest.sumByDoubleList())
+    }
+
+    @Test
+    fun whenFoldList_thenReturnsValue(){
+        assertEquals(73, classUnderTest.foldList())
+    }
+
+    @Test
+    fun whenFoldRightList_thenReturnsValue(){
+        assertEquals(73, classUnderTest.foldRightList())
+    }
+
+    @Test
+    fun whenFoldIndexedList_thenReturnsValue(){
+        assertEquals(89, classUnderTest.foldIndexedList())
+    }
+
+    @Test
+    fun whenFoldRightIndexedList_thenReturnsValue(){
+        assertEquals(89, classUnderTest.foldRightIndexedList())
+    }
+
+    @Test
+    fun whenReduceList_thenReturnsValue(){
+        assertEquals(-25, classUnderTest.reduceList())
+    }
+
+    @Test
+    fun whenReduceRightList_thenReturnsValue(){
+        assertEquals(-11, classUnderTest.reduceRightList())
+    }
+
+    @Test
+    fun whenReduceIndexedList_thenReturnsValue(){
+        assertEquals(-10, classUnderTest.reduceIndexedList())
+    }
+
+    @Test
+    fun whenReduceRightIndexedList_thenReturnsValue(){
+        assertEquals(5, classUnderTest.reduceRightIndexedList())
+    }
+}
\ No newline at end of file

From 82203b222e89543accda497ec9450db0adbb6e73 Mon Sep 17 00:00:00 2001
From: Anirban Chatterjee <canirban99@gmail.com>
Date: Mon, 24 Aug 2020 09:59:39 +0200
Subject: [PATCH 2/4] Removed print statements

---
 .../kotlin/collections/AggregateOperations.kt | 56 ++++++-------------
 1 file changed, 16 insertions(+), 40 deletions(-)

diff --git a/core-kotlin-modules/core-kotlin-collections/src/main/kotlin/com/baeldung/kotlin/collections/AggregateOperations.kt b/core-kotlin-modules/core-kotlin-collections/src/main/kotlin/com/baeldung/kotlin/collections/AggregateOperations.kt
index 854190382c..3a348aafaa 100644
--- a/core-kotlin-modules/core-kotlin-collections/src/main/kotlin/com/baeldung/kotlin/collections/AggregateOperations.kt
+++ b/core-kotlin-modules/core-kotlin-collections/src/main/kotlin/com/baeldung/kotlin/collections/AggregateOperations.kt
@@ -50,82 +50,58 @@ class AggregateOperations {
     }
 
     fun foldList(): Int {
-        println("fold operation")
-        val result = numbers.fold(100) { total, it ->
+        return numbers.fold(100) { total, it ->
             println("total = $total, it = $it")
             total - it
-        }
-        println(result) // ((((100 - 1)-15)-3)-8) = 73
-        return result
+        } // ((((100 - 1)-15)-3)-8) = 73
     }
 
     fun foldRightList(): Int {
-        println("foldRight operation")
-        val result = numbers.foldRight(100) { it, total ->
+        return numbers.foldRight(100) { it, total ->
             println("total = $total, it = $it")
             total - it
-        }
-        println(result) // ((((100-8)-3)-15)-1) = 73
-        return result
+        }  // ((((100-8)-3)-15)-1) = 73
     }
 
     fun foldIndexedList(): Int {
-        println("foldIndexed operation")
-        val result = numbers.foldIndexed(100) { index, total, it ->
+        return numbers.foldIndexed(100) { index, total, it ->
             println("total = $total, it = $it, index = $index")
             if (index.minus(2) >= 0) total - it else total
-        }
-        println(result) // ((100 - 3)-8) = 89
-        return result
+        } // ((100 - 3)-8) = 89
     }
 
     fun foldRightIndexedList(): Int {
-        println("foldRightIndexed operation")
-        val result = numbers.foldRightIndexed(100) { index, it, total ->
+        return numbers.foldRightIndexed(100) { index, it, total ->
             println("total = $total, it = $it, index = $index")
             if (index.minus(2) >= 0) total - it else total
-        }
-        println(result) // ((100 - 8)-3) = 89
-        return result
+        } // ((100 - 8)-3) = 89
     }
 
     fun reduceList(): Int {
-        println("reduce operation")
-        val result = numbers.reduce { total, it ->
+        return numbers.reduce { total, it ->
             println("total = $total, it = $it")
             total - it
-        }
-        println(result) // (((1 - 15)-3)-8) = -25
-        return result
+        } // (((1 - 15)-3)-8) = -25
     }
 
     fun reduceRightList(): Int {
-        println("reduceRight operation")
-        val result = numbers.reduceRight() { it, total ->
+        return numbers.reduceRight() { it, total ->
             println("total = $total, it = $it")
             total - it
-        }
-        println(result) // ((8-3)-15)-1) = -11
-        return result
+        } // ((8-3)-15)-1) = -11
     }
 
     fun reduceIndexedList(): Int {
-        println("reduceIndexed operation")
-        val result = numbers.reduceIndexed { index, total, it ->
+        return numbers.reduceIndexed { index, total, it ->
             println("total = $total, it = $it, index = $index")
             if (index.minus(2) >= 0) total - it else total
-        }
-        println(result) // ((1-3)-8) = -10
-        return result
+        } // ((1-3)-8) = -10
     }
 
     fun reduceRightIndexedList(): Int {
-        println("reduceRightIndexed operation")
-        val result = numbers.reduceRightIndexed { index, it, total ->
+        return numbers.reduceRightIndexed { index, it, total ->
             println("total = $total, it = $it, index = $index")
             if (index.minus(2) >= 0) total - it else total
-        }
-        println(result) // ((8-3) = 5
-        return result
+        } // ((8-3) = 5
     }
 }

From 531751568cacd590d923b17d1b41940872c46da9 Mon Sep 17 00:00:00 2001
From: Anirban Chatterjee <canirban99@gmail.com>
Date: Sun, 30 Aug 2020 13:23:51 +0200
Subject: [PATCH 3/4] Moved to new module

---
 .../core-kotlin-collections-2/README.md       |  7 +++
 .../core-kotlin-collections-2/pom.xml         | 47 +++++++++++++++++++
 .../AggregateOperations.kt                    |  2 +-
 .../AggregateOperationsUnitTest.kt            |  2 +-
 core-kotlin-modules/pom.xml                   |  1 +
 5 files changed, 57 insertions(+), 2 deletions(-)
 create mode 100644 core-kotlin-modules/core-kotlin-collections-2/README.md
 create mode 100644 core-kotlin-modules/core-kotlin-collections-2/pom.xml
 rename core-kotlin-modules/{core-kotlin-collections/src/main/kotlin/com/baeldung/kotlin/collections => core-kotlin-collections-2/src/main/kotlin/com.baeldung.aggregate}/AggregateOperations.kt (98%)
 rename core-kotlin-modules/{core-kotlin-collections/src/test/kotlin/com/baeldung/kotlin/collections => core-kotlin-collections-2/src/test/kotlin/com.baeldung.aggregate}/AggregateOperationsUnitTest.kt (98%)

diff --git a/core-kotlin-modules/core-kotlin-collections-2/README.md b/core-kotlin-modules/core-kotlin-collections-2/README.md
new file mode 100644
index 0000000000..2dc180b5b3
--- /dev/null
+++ b/core-kotlin-modules/core-kotlin-collections-2/README.md
@@ -0,0 +1,7 @@
+## Core Kotlin Collections
+
+This module contains articles about core Kotlin collections.
+
+### Relevant articles:
+
+
diff --git a/core-kotlin-modules/core-kotlin-collections-2/pom.xml b/core-kotlin-modules/core-kotlin-collections-2/pom.xml
new file mode 100644
index 0000000000..be462eed45
--- /dev/null
+++ b/core-kotlin-modules/core-kotlin-collections-2/pom.xml
@@ -0,0 +1,47 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>core-kotlin-collections-2</artifactId>
+    <name>core-kotlin-collections-2</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung.core-kotlin-modules</groupId>
+        <artifactId>core-kotlin-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.jetbrains.kotlin</groupId>
+            <artifactId>kotlin-stdlib-jdk8</artifactId>
+            <version>${kotlin.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-math3</artifactId>
+            <version>${commons-math3.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.jetbrains.kotlin</groupId>
+            <artifactId>kotlin-test</artifactId>
+            <version>${kotlin.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <kotlin.version>1.3.30</kotlin.version>
+        <commons-math3.version>3.6.1</commons-math3.version>
+        <assertj.version>3.10.0</assertj.version>
+    </properties>
+
+</project>
\ No newline at end of file
diff --git a/core-kotlin-modules/core-kotlin-collections/src/main/kotlin/com/baeldung/kotlin/collections/AggregateOperations.kt b/core-kotlin-modules/core-kotlin-collections-2/src/main/kotlin/com.baeldung.aggregate/AggregateOperations.kt
similarity index 98%
rename from core-kotlin-modules/core-kotlin-collections/src/main/kotlin/com/baeldung/kotlin/collections/AggregateOperations.kt
rename to core-kotlin-modules/core-kotlin-collections-2/src/main/kotlin/com.baeldung.aggregate/AggregateOperations.kt
index 3a348aafaa..a09e101b59 100644
--- a/core-kotlin-modules/core-kotlin-collections/src/main/kotlin/com/baeldung/kotlin/collections/AggregateOperations.kt
+++ b/core-kotlin-modules/core-kotlin-collections-2/src/main/kotlin/com.baeldung.aggregate/AggregateOperations.kt
@@ -1,4 +1,4 @@
-package com.baeldung.kotlin.collections
+package com.baeldung.aggregate
 
 class AggregateOperations {
     private val numbers = listOf(1, 15, 3, 8)
diff --git a/core-kotlin-modules/core-kotlin-collections/src/test/kotlin/com/baeldung/kotlin/collections/AggregateOperationsUnitTest.kt b/core-kotlin-modules/core-kotlin-collections-2/src/test/kotlin/com.baeldung.aggregate/AggregateOperationsUnitTest.kt
similarity index 98%
rename from core-kotlin-modules/core-kotlin-collections/src/test/kotlin/com/baeldung/kotlin/collections/AggregateOperationsUnitTest.kt
rename to core-kotlin-modules/core-kotlin-collections-2/src/test/kotlin/com.baeldung.aggregate/AggregateOperationsUnitTest.kt
index 1fb26760fc..a619759b0a 100644
--- a/core-kotlin-modules/core-kotlin-collections/src/test/kotlin/com/baeldung/kotlin/collections/AggregateOperationsUnitTest.kt
+++ b/core-kotlin-modules/core-kotlin-collections-2/src/test/kotlin/com.baeldung.aggregate/AggregateOperationsUnitTest.kt
@@ -1,4 +1,4 @@
-package com.baeldung.kotlin.collections
+package com.baeldung.aggregate
 
 import org.junit.jupiter.api.Test
 import kotlin.test.assertEquals
diff --git a/core-kotlin-modules/pom.xml b/core-kotlin-modules/pom.xml
index 8b626e1c1b..67520a7dee 100644
--- a/core-kotlin-modules/pom.xml
+++ b/core-kotlin-modules/pom.xml
@@ -21,6 +21,7 @@
         <module>core-kotlin-advanced</module>
         <module>core-kotlin-annotations</module>
         <module>core-kotlin-collections</module>
+        <module>core-kotlin-collections-2</module>
         <module>core-kotlin-concurrency</module>
         <module>core-kotlin-date-time</module>
         <module>core-kotlin-design-patterns</module>

From c6d95556171005b68cc4a6194de97de2cb5406ff Mon Sep 17 00:00:00 2001
From: Anirban Chatterjee <canirban99@gmail.com>
Date: Mon, 31 Aug 2020 20:38:06 +0200
Subject: [PATCH 4/4] Refactored package

---
 .../baeldung/aggregate}/AggregateOperations.kt                    | 0
 .../baeldung/aggregate}/AggregateOperationsUnitTest.kt            | 0
 2 files changed, 0 insertions(+), 0 deletions(-)
 rename core-kotlin-modules/core-kotlin-collections-2/src/main/kotlin/{com.baeldung.aggregate => com/baeldung/aggregate}/AggregateOperations.kt (100%)
 rename core-kotlin-modules/core-kotlin-collections-2/src/test/kotlin/{com.baeldung.aggregate => com/baeldung/aggregate}/AggregateOperationsUnitTest.kt (100%)

diff --git a/core-kotlin-modules/core-kotlin-collections-2/src/main/kotlin/com.baeldung.aggregate/AggregateOperations.kt b/core-kotlin-modules/core-kotlin-collections-2/src/main/kotlin/com/baeldung/aggregate/AggregateOperations.kt
similarity index 100%
rename from core-kotlin-modules/core-kotlin-collections-2/src/main/kotlin/com.baeldung.aggregate/AggregateOperations.kt
rename to core-kotlin-modules/core-kotlin-collections-2/src/main/kotlin/com/baeldung/aggregate/AggregateOperations.kt
diff --git a/core-kotlin-modules/core-kotlin-collections-2/src/test/kotlin/com.baeldung.aggregate/AggregateOperationsUnitTest.kt b/core-kotlin-modules/core-kotlin-collections-2/src/test/kotlin/com/baeldung/aggregate/AggregateOperationsUnitTest.kt
similarity index 100%
rename from core-kotlin-modules/core-kotlin-collections-2/src/test/kotlin/com.baeldung.aggregate/AggregateOperationsUnitTest.kt
rename to core-kotlin-modules/core-kotlin-collections-2/src/test/kotlin/com/baeldung/aggregate/AggregateOperationsUnitTest.kt