Add startCase function (#94)

src/main/java/strman/Strman.java

@@ -1404,6 +1404,21 @@ public static String[] chop(String input, int step) {
                 .toArray(String[]::new);
     }
 
+    /**
+     * Converts a String into its Start Case version
+     * https://en.wikipedia.org/wiki/Letter_case#Stylistic_or_specialised_usage
+     *
+     * @param input The input String
+     * @return Start Case String
+     */
+    public static String startCase(final String input) {
+        validate(input, NULL_STRING_PREDICATE, NULL_STRING_MSG_SUPPLIER);
+        // split into a word when we encounter a space, or an underscore, or a dash, or a switch from lower to upper case
+        String[] words = words(input, "\\s|_|-|(?<=[a-z])(?=[A-Z])");
+        return Arrays.stream(words).filter(w -> !w.trim().isEmpty())
+            .map(w -> upperFirst(w.toLowerCase())).collect(joining(" "));
+    }
+
     private static void validate(String value, Predicate<String> predicate, final Supplier<String> supplier) {
         if (predicate.test(value)) {
             throw new IllegalArgumentException(supplier.get());

src/test/java/strman/StrmanTests.java

@@ -1186,4 +1186,22 @@ public void chop_shouldChopStringByStep() throws Exception {
         assertThat(chop("whitespace", 3).length, equalTo(4));
         assertThat(chop("whitespace", 0)[0].length(), equalTo(10));
     }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void startCase_shouldThrowException() throws Exception {
+        startCase(null);
+    }
+
+    @Test
+    public void startCase_shouldStartCaseInputString() throws Exception {
+        assertThat(startCase(""), equalTo(""));
+        assertThat(startCase("ALL CAPS"), equalTo("All Caps"));
+        assertThat(startCase("camelCase"), equalTo("Camel Case"));
+        assertThat(startCase("kebab-case"), equalTo("Kebab Case"));
+        assertThat(startCase("Snake_case"), equalTo("Snake Case"));
+        assertThat(startCase("  spaces  "), equalTo("Spaces"));
+        assertThat(startCase("spaces    between    words"), equalTo("Spaces Between Words"));
+        assertThat(startCase("--dashes--"), equalTo("Dashes"));
+        assertThat(startCase("dashes----between----words"), equalTo("Dashes Between Words"));
+    }
 }