Check if a string contains only alphabets in Java
Given a string, the task is to write a Java program to check whether the string contains only alphabets or not. If so, then print true, otherwise false.
Examples:
Input: GeeksforGeeks
Output: true
Explanation: The given string contains only alphabets so the output is true.
Input: GeeksforGeeks2020
Output: false
Explanation: The given string contains alphabets and numbers so the output is false.
Input: “”
Output: false
Explanation: The given string is empty so the output is false.
Method 1: This problem can be solved using the ASCII values. Please refer this article for this approach.
Method 2: This problem can be solved using Lambda expression. Please refer this article for this approach.
Method 3: This problem can be solved using Regular Expression. Please refer this article for this approach.
Method 4: This approach uses the methods of Character class in Java
- The idea is to iterate over each character of the string and check whether the specified character is a letter or not using Character.isLetter() method.
- If the character is a letter then continue, else return false.
- If we are able to iterate over the whole string, then return true.
Below is the implementation of the above approach:
Java
class GFG {
public static boolean onlyAlphabets(
String str, int n)
{
if (str == null || str == "" ) {
return false ;
}
for ( int i = 0 ; i < n; i++) {
if (!Character
.isLetter(str.charAt(i))) {
return false ;
}
}
return true ;
}
public static void main(String args[])
{
String str = "GeeksforGeeks" ;
int len = str.length();
System.out.println(
onlyAlphabets(str, len));
}
}
|
Time Complexity: O(N), where N is the size of the given string.
Auxiliary Space: O(1), no extra space required so it is a constant.
Method 5 : Using contains() method and ArrayList
Java
import java.util.*;
import java.lang.*;
class Main{
public static boolean onlyAlphabets(String str, int n)
{
if (str == null || str == "" ) {
return false ;
}
ArrayList<Character> alphabets = new ArrayList<Character>();
String alpha = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ" ;
for ( int i= 0 ;i<alpha.length();i++)
{
alphabets.add(alpha.charAt(i));
}
for ( int i = 0 ; i < n; i++) {
if (!alphabets.contains(str.charAt(i))) {
return false ;
}
}
return true ;
}
public static void main(String args[])
{
String str = "GeeksforGeeks" ;
int len = str.length();
System.out.println(
onlyAlphabets(str, len));
}
}
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Last Updated :
02 Nov, 2022
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