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

Given a String, the task is to check whether a string contains only alphabets or not.

Examples:

Input : GeeksforGeeks
Output : True

Input : Geeks4Geeks
Output : False

Input : null
Output : False

The idea is to use isLetter() method of Character class.

Algorithm:

  1. Get the string
  2. Match the string:
    • Check if the string is empty or not. If empty, return false
    • Check if the string is null or not. If null, return false.
    • If the string is neither empty nor null,
      then check using Lambda Expression Character::isLetter().
  3. Return true if matched

Pseudocode:



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public static boolean isStringOnlyAlphabet(String str)
{
    return ((!str.equals(""))
            && (str != null)
            && (str.chars().allMatch(Character::isLetter)));
}

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Program: Checking if String contains only Alphabets.











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// Java program to check if String contains only Alphabets 


// using Lambda Expression 


  


class GFG { 


  


    // Function to check String for only Alphabets 


    public static boolean isStringOnlyAlphabet(String str) 


    { 


        return ((str != null) 


                && (!str.equals("")) 


                && (str.chars().allMatch(Character::isLetter))); 


    } 


  


    // 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)); 


    } 


} 



















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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 Regex


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