BAEL-6435: Reverse a String in Java 8 using Lambda and Streams (#13910)

core-java-modules/core-java-string-algorithms/src/main/java/com/baeldung/reverse/ReverseStringExamples.java

@@ -1,5 +1,9 @@
 package com.baeldung.reverse;
 
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+import java.util.stream.Stream;
+
 import org.apache.commons.lang3.StringUtils;
 
 public class ReverseStringExamples {
@@ -46,11 +50,43 @@ public class ReverseStringExamples {
         }
 
         return output.toString()
-            .trim();
+          .trim();
     }
 
     public static String reverseTheOrderOfWordsUsingApacheCommons(String sentence) {
         return StringUtils.reverseDelimited(sentence, ' ');
     }
 
+    public static String reverseUsingIntStreamRangeMethod(String str) {
+        if (str == null) {
+            return null;
+        }
+
+        char[] charArray = str.toCharArray();
+        return IntStream.range(0, str.length())
+          .mapToObj(i -> charArray[str.length() - i - 1])
+          .collect(StringBuilder::new, StringBuilder::append, StringBuilder::append)
+          .toString();
+    }
+
+    public static String reverseUsingStreamOfMethod(String str) {
+        if (str == null) {
+            return null;
+        }
+
+        return Stream.of(str)
+          .map(string -> new StringBuilder(string).reverse())
+          .collect(Collectors.joining());
+    }
+
+    public static String reverseUsingCharsMethod(String str) {
+        if (str == null) {
+            return null;
+        }
+
+        return str.chars()
+          .mapToObj(c -> (char) c)
+          .reduce("", (a, b) -> b + a, (a2, b2) -> b2 + a2);
+    }
+
 }