



Check if a string contains only alphabets in Java using Regex


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



Recommended: Please try your approach on {IDE} first, before moving on to the solution.

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("\nTest Case 2:"); 
  
        String str2 = "Geeks4Geeks"; 
        System.out.println("Input: " + str2); 
        System.out.println("Output: " + isStringOnlyAlphabet(str2)); 
  
        // Checking for null String 
        System.out.println("\nTest Case 3:"); 
  
        String str3 = null; 
        System.out.println("Input: " + str3); 
        System.out.println("Output: " + isStringOnlyAlphabet(str3)); 
  
        // Checking for empty String 
        System.out.println("\nTest Case 4:"); 
  
        String str4 = ""; 
        System.out.println("Input: " + str4); 
        System.out.println("Output: " + isStringOnlyAlphabet(str4)); 
    } 
} 



















Output:


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
Check if a string contains only alphabets in Java using Lambda expression





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