Given a string, the task is to check whether a string contains only alphabets or not using Regex in JAVA.
Examples:
Input : GeeksforGeeks Output : True Input : Geeks4Geeks Output : False Input : null Output : False
In this article, the characters of the string are checked one by one using Regex.
Regular Expressions or Regex is an API for defining String patterns that can be used for searching, manipulating and editing a text. It is widely used to define constraint on strings such as password. Regular Expressions are provided under java.util.regex package.
The Regex
^[a-zA-Z]*$
can be used to check a string for alphabets. String.matches() method is used to check whether or not the string matches the given regex.
Algorithm:
- Get the string
- Match the string with the Regex using matches().
- Return true is matched
Pseudocode:
public static boolean isStringOnlyAlphabet(String str) { return ((!str.equals("")) && (str != null) && (str.matches("^[a-zA-Z]*$"))); } |
Program: Checking for String containing only Alphabets
// Java program to check if String contains only Alphabets // using Regular Expression class GFG { // Function to check String for only Alphabets public static boolean isStringOnlyAlphabet(String str) { return ((str != null) && (!str.equals("")) && (str.matches("^[a-zA-Z]*$"))); } // Main method public static void main(String[] args) { // Checking for True case System.out.println("Test Case 1:"); String str1 = "GeeksforGeeks"; System.out.println("Input: " + str1); System.out.println("Output: " + isStringOnlyAlphabet(str1)); // Checking for String with numeric characters System.out.println("
Test Case 2:"); String str2 = "Geeks4Geeks"; System.out.println("Input: " + str2); System.out.println("Output: " + isStringOnlyAlphabet(str2)); // Checking for null String System.out.println("
Test Case 3:"); String str3 = null; System.out.println("Input: " + str3); System.out.println("Output: " + isStringOnlyAlphabet(str3)); // Checking for empty String System.out.println("
Test Case 4:"); String str4 = ""; System.out.println("Input: " + str4); System.out.println("Output: " + isStringOnlyAlphabet(str4)); } } |
Test Case 1: Input: GeeksforGeeks Output: true Test Case 2: Input: Geeks4Geeks Output: false Test Case 3: Input: null Output: false Test Case 4: Input: Output: false
Check if a string contains only alphabets in Java using ASCII values
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