Check if a string contains only alphabets in Java using ASCII values

Given a string, the task is to check whether a string contains only alphabets or not using ASCII values 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 their ASCII values.

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 the string characters one by one for alphabet using ASCII values.
  3. Return true if matched

Pseudocode:



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public static boolean isStringOnlyAlphabet(String str)
{
    if (str == null || str.equals("")) {
        return false;
    }
    for (int i = 0; i < str.length(); i++) {
        char ch = str.charAt(i);
        if ((!(ch >= 'A' && ch <= 'Z'))
            && (!(ch >= 'a' && ch <= 'z'))) {
            return false;
        }
    }
    return true;
}

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Program: Checking for String containing only Alphabets











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// Java program to check if String contains only Alphabets 


// using ASCII values 


  


class GFG { 


  


    // Function to check String for only Alphabets 


    public static boolean isStringOnlyAlphabet(String str) 


    { 


        if (str == null || str.equals("")) { 


            return false; 


        } 


        for (int i = 0; i < str.length(); i++) { 


            char ch = str.charAt(i); 


            if ((!(ch >= 'A' && ch <= 'Z')) 


                && (!(ch >= 'a' && ch <= 'z'))) { 


                return false; 


            } 


        } 


        return true; 


    } 


  


    // 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 Lambda expression

Check if a string contains only alphabets in Java using Regex


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