FunctionalJava article (#2586)

* Update pom.xml with functionalJava dependencies

* Add functionalJava classes

* update README.md

libraries/README.md

@@ -31,7 +31,7 @@
 - [Guide to Apache Commons CircularFifoQueue](http://www.baeldung.com/commons-circular-fifo-queue)
 - [Quick Guide to RSS with Rome](http://www.baeldung.com/rome-rss)
 - [Introduction to NoException](http://www.baeldung.com/no-exception)
-
+- [Introduction to FunctionalJava](http://www.baeldung.com/functional-java)
 
 The libraries module contains examples related to small libraries that are relatively easy to use and does not require any separate module of its own.
 

libraries/pom.xml

@@ -554,6 +554,26 @@
             <artifactId>protonpack</artifactId>
             <version>${protonpack.version}</version>
         </dependency>
+        <dependency>
+	    <groupId>org.functionaljava</groupId>
+	    <artifactId>functionaljava</artifactId>
+	    <version>4.7</version>
+	</dependency>
+	<dependency>
+	    <groupId>org.functionaljava</groupId>
+	    <artifactId>functionaljava-java8</artifactId>
+	    <version>4.7</version>
+        </dependency>
+        <dependency>
+	    <groupId>org.functionaljava</groupId>
+	    <artifactId>functionaljava-quickcheck</artifactId>
+	    <version>4.7</version>
+	</dependency>
+	<dependency>
+	    <groupId>org.functionaljava</groupId>
+	    <artifactId>functionaljava-java-core</artifactId>
+	    <version>4.7</version>
+        </dependency>
     </dependencies>
     <repositories>
         <repository>

libraries/src/main/java/com/baeldung/fj/FunctionalJavaIOMain.java

@@ -0,0 +1,47 @@
+package com.baeldung.fj;
+
+import fj.F;
+import fj.F1Functions;
+import fj.Unit;
+import fj.data.IO;
+import fj.data.IOFunctions;
+
+public class FunctionalJavaIOMain {
+    
+    public static IO<Unit> printLetters(final String s) {
+        return () -> {
+            for (int i = 0; i < s.length(); i++) {
+                System.out.println(s.charAt(i));
+            }
+            return Unit.unit();
+        };
+    }
+
+    public static void main(String[] args) {
+
+        F<String, IO<Unit>> printLetters = i -> printLetters(i);
+
+        IO<Unit> lowerCase = IOFunctions
+          .stdoutPrintln("What's your first Name ?");
+
+        IO<Unit> input = IOFunctions.stdoutPrint("First Name: ");
+
+        IO<Unit> userInput = IOFunctions.append(lowerCase, input);
+
+        IO<String> readInput = IOFunctions.stdinReadLine();
+
+        F<String, String> toUpperCase = i -> i.toUpperCase();
+
+        F<String, IO<Unit>> transformInput = F1Functions
+          .<String, IO<Unit>, String> o(printLetters).f(toUpperCase);
+
+        IO<Unit> readAndPrintResult = IOFunctions.bind(readInput,
+          transformInput);
+
+        IO<Unit> program = IOFunctions.bind(userInput,
+          nothing -> readAndPrintResult);
+
+        IOFunctions.toSafe(program).run();
+
+    }
+}

libraries/src/main/java/com/baeldung/fj/FunctionalJavaMain.java

@@ -0,0 +1,48 @@
+package com.baeldung.fj;
+
+import fj.F;
+import fj.Show;
+import fj.data.Array;
+import fj.data.List;
+import fj.data.Option;
+import fj.function.Characters;
+import fj.function.Integers;
+
+public class FunctionalJavaMain {
+
+    public static final F<Integer, Boolean> isEven = i -> i % 2 == 0;
+    
+    public static void main(String[] args) {
+        
+        List<Integer> fList = List.list(3, 4, 5, 6);
+        List<Boolean> evenList = fList.map(isEven);
+        Show.listShow(Show.booleanShow).println(evenList);
+        
+        fList = fList.map(i -> i + 1);
+        Show.listShow(Show.intShow).println(fList);
+        
+        Array<Integer> a = Array.array(17, 44, 67, 2, 22, 80, 1, 27);
+        Array<Integer> b = a.filter(Integers.even);
+        Show.arrayShow(Show.intShow).println(b);
+
+        Array<String> array = Array.array("Welcome", "To", "baeldung");
+        Boolean isExist = array.exists(s -> List.fromString(s).forall(Characters.isLowerCase));
+        System.out.println(isExist);
+        
+        Array<Integer> intArray = Array.array(17, 44, 67, 2, 22, 80, 1, 27);
+        int sum = intArray.foldLeft(Integers.add, 0);
+        System.out.println(sum);
+        
+        Option<Integer> n1 = Option.some(1);
+        Option<Integer> n2 = Option.some(2);
+
+        F<Integer, Option<Integer>> f1 = i -> i % 2 == 0 ? Option.some(i + 100) : Option.none();
+
+        Option<Integer> result1 = n1.bind(f1);
+        Option<Integer> result2 = n2.bind(f1);
+
+        Show.optionShow(Show.intShow).println(result1);
+        Show.optionShow(Show.intShow).println(result2);
+    }
+
+}