Check if a String Contains Only Alphabets in Java using ASCII Values
Last Updated : 08 Feb, 2024
Improve
Given a string, now we all know that the task is to check whether a string contains only alphabets. Now we will be iterating character by character and checking the corresponding ASCII value attached to it. If not found means there is some other character other than "a-z" or "A-Z". If we traverse the whole string and land up on finding all characters in a string within this domain pool then the string is surely only alphabetic.
Examples:
Input: GeeksforGeeks
Output: TrueInput: Geeks4Geeks
Output: FalseInput: null
Output: False
In this article, the characters of the string are checked one by one using their ASCII values.
Algorithm:
- Get the string
- 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.
- Return true if matched
Example 1:
// Java Program to Check if a String Contains Only Alphabets
// Using ASCII values
// Importing required classes
import java.util.*;
// Class 1
// Main class
class GFG {
// Main driver method
public static void main(String[] args)
{
// Creating object of helper class
Helper h = new Helper();
// Print statement
System.out.println(
h.isStringOnlyAlphabet("geeksforgeeks"));
}
}
// Class 2
// Helper class
class Helper {
public static boolean isStringOnlyAlphabet(String str)
{
// If string is empty or null
if (str == null || str.equals("")) {
// Return false
return false;
}
// If we reach here we have character/s in string
for (int i = 0; i < str.length(); i++) {
// Getting character at indices
// using charAt() method
char ch = str.charAt(i);
if ((!(ch >= 'A' && ch <= 'Z'))
&& (!(ch >= 'a' && ch <= 'z'))) {
return false;
}
}
// String is only alphabetic
return true;
}
}
Output
true
Complexity Analysis:
- Time Complexity: O(N), where N is the length of the string.
- Auxiliary Space: O(1), no extra space required so it is a constant.
Example 2:
// Java program to check if String contains only Alphabets
// Using ASCII Values
// Main class
class GFG {
// Method 1
// To check String for only Alphabets
public static boolean isStringOnlyAlphabet(String str)
{
// If there is no string
if (str == null || str.equals("")) {
return false;
}
// Iterating as now we encounter string
// using length() method
for (int i = 0; i < str.length(); i++) {
char ch = str.charAt(i);
// Checking for any other aphabetic character
// present in string
if ((!(ch >= 'A' && ch <= 'Z'))
&& (!(ch >= 'a' && ch <= 'z'))) {
// Then string is not only alphabetic
return false;
}
}
// If we reach here, it means
// string is only aphabetic
return true;
}
// Method 2
// 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
Complexity Analysis:
- Time Complexity: O(N), where N is the length of the string.
- Auxiliary Space: O(1), no extra space required so it is a constant.
Related Articles:
- Check if a string contains only alphabets in Java using Lambda expression
- Check if a string contains only alphabets in Java using Regex
