Add UnicodeLetterChecker to check if String contains Unicode

core-java-modules/core-java-string-operations-7/src/main/java/com/baeldung/unicode/UnicodeLetterChecker.java

@@ -0,0 +1,27 @@
+package com.baeldung.unicode;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import org.apache.commons.lang3.StringUtils;
+
+public class UnicodeLetterChecker {
+    public boolean characterClassCheck(String input) {
+        for (char c : input.toCharArray()) {
+            if (!Character.isLetter(c)) {
+                return false;
+            }
+        }
+        return true;
+    }
+    public boolean regexCheck(String input) {
+        Pattern pattern = Pattern.compile("^\\p{L}+$");
+        Matcher matcher = pattern.matcher(input);
+        return matcher.matches();
+    }
+    public boolean isAlphaCheck(String input) {
+        return StringUtils.isAlpha(input);
+    }
+    public boolean StreamsCheck(String input){
+        return input.codePoints().allMatch(Character::isLetter);
+    }
+}