Added examplify() which generates a String by example.

src/main/java/net/datafaker/Faker.java

@@ -365,6 +365,20 @@ public String regexify(String regex) {
         return fakeValuesService.regexify(regex);
     }
 
+    /**
+     * Generates a String by example. The output string will have the same pattern as the input string.
+     *
+     * For example:
+     *   "AAA" becomes "KRA"
+     *   "abc" becomes "uio"
+     *   "948" becomes "345"
+     *   "A19c" becomes "Z20d"
+     *
+     * @param example The input string
+     * @return The output string based on the input pattern
+     */
+    public String examplify(String example) {return fakeValuesService.examplify(example);}
+
     public RandomService random() {
         return this.randomService;
     }

src/main/java/net/datafaker/service/FakeValuesService.java

@@ -240,6 +240,31 @@ public String regexify(String regex) {
         return generex.random();
     }
 
+    /**
+     * Generates a String by example. The output string will have the same pattern as the input string.
+     */
+    public String examplify(String example) {
+        StringBuilder sb = new StringBuilder();
+        if(example == null) {
+            return null;
+        }
+
+        char[] chars = example.toCharArray();
+
+        for (char character : chars) {
+            if (Character.isLetter(character)) {
+                sb.append(letterify("?", Character.isUpperCase(character)));
+            } else if(Character.isDigit(character)) {
+                sb.append(randomService.nextInt(10));
+            } else {
+                sb.append(character);
+            }
+        }
+
+        return sb.toString();
+
+    }
+
     /**
      * Returns a string with the '?' characters in the parameter replaced with random alphabetic
      * characters.

src/test/java/net/datafaker/FakerTest.java

@@ -16,6 +16,31 @@
 
 public class FakerTest extends AbstractFakerTest {
 
+    @Test
+    public void examplifyUppercaseLetters() {
+        assertThat(faker.examplify("ABC"), matchesRegularExpression("[A-Z]{3}"));
+    }
+
+    @Test
+    public void examplifyLowercaseLetters() {
+        assertThat(faker.examplify("abc"), matchesRegularExpression("[a-z]{3}"));
+    }
+
+    @Test
+    public void examplifyNumbers() {
+        assertThat(faker.examplify("489321"), matchesRegularExpression("[0-9]{6}"));
+    }
+
+    @Test
+    public void examplifyMixed() {
+        assertThat(faker.examplify("abc123ABC1zzz"), matchesRegularExpression("[a-z]{3}[0-9]{3}[A-Z]{3}[0-9][a-z]{3}"));
+    }
+
+    @Test
+    public void examplifyWithSpacesAndSpecialCharacters() {
+        assertThat(faker.examplify("The number 4!"), matchesRegularExpression("[A-Z][a-z]{2} [a-z]{6} [0-9]!"));
+    }
+
     @Test
     public void bothifyShouldGenerateLettersAndNumbers() {
         assertThat(faker.bothify("????##@gmail.com"), matchesRegularExpression("\\w{4}\\d{2}@gmail.com"));