From db5a8b5d658615f6bec6112facd670f8e44f84d1 Mon Sep 17 00:00:00 2001
From: Shekhar Gulati <shekhargulati84@gmail.com>
Date: Fri, 23 Jun 2017 21:04:12 +0530
Subject: [PATCH] Resolved #81

---
 src/main/java/strman/Strman.java      | 22 ++++++++++++++++++++++
 src/test/java/strman/StrmanTests.java |  8 ++++++++
 2 files changed, 30 insertions(+)

diff --git a/src/main/java/strman/Strman.java b/src/main/java/strman/Strman.java
index 0e16055..83d4808 100644
--- a/src/main/java/strman/Strman.java
+++ b/src/main/java/strman/Strman.java
@@ -1368,6 +1368,27 @@ public abstract class Strman {
         return upperFirst(underscored(input).replaceAll("_", " "));
     }
 
+    /**
+     * Returns a copy of the string in which all the case-based characters have had their case swapped.
+     *
+     * @param input Input string
+     * @return String with all the case swapped
+     */
+    public static String swapCase(String input) {
+        if (input == null || input.length() == 0) {
+            return "";
+        }
+        StringBuilder resultBuilder = new StringBuilder();
+        for (char ch : input.toCharArray()) {
+            if (Character.isUpperCase(ch)) {
+                resultBuilder.append(Character.toLowerCase(ch));
+            } else {
+                resultBuilder.append(Character.toUpperCase(ch));
+            }
+        }
+        return resultBuilder.toString();
+    }
+
     private static void validate(String value, Predicate<String> predicate, final Supplier<String> supplier) {
         if (predicate.test(value)) {
             throw new IllegalArgumentException(supplier.get());
@@ -1391,5 +1412,6 @@ public abstract class Strman {
     private static boolean isNullOrEmpty(String input) {
         return input == null || input.isEmpty();
     }
+
 }
 
diff --git a/src/test/java/strman/StrmanTests.java b/src/test/java/strman/StrmanTests.java
index 30702d8..73f9dcd 100644
--- a/src/test/java/strman/StrmanTests.java
+++ b/src/test/java/strman/StrmanTests.java
@@ -1168,4 +1168,12 @@ public class StrmanTests {
         assertThat(dasherize(""), equalTo(""));
         assertThat(dasherize(null), equalTo(""));
     }
+
+    @Test
+    public void swapCase_shouldSwapCaseOfCharacters() throws Exception {
+        assertThat(swapCase("AaBbCcDdEe"), equalTo("aAbBcCdDeE"));
+        assertThat(swapCase("Hello World"), equalTo("hELLO wORLD"));
+        assertThat(swapCase(""), equalTo(""));
+        assertThat(swapCase(null), equalTo(""));
+    }
 }