Check if a given string is Pangram in Java

A pangram is a string that contains every letter of the English alphabet (a to z) at least once. The check is generally case-insensitive, so uppercase and lowercase letters are treated as the same.

• The check should be case-insensitive, so uppercase and lowercase letters are treated equally.
• Spaces, digits, and special characters are ignored.

Examples:

Input: str = "Abcdefghijklmnopqrstuvwxyz"
Output: Yes

Input: str = "GeeksForGeeks"
Output: No

Methods to check Pangram String

1. Using Frequency Array

• Convert the string to lowercase.
• Create a boolean array of size 26 to track letters a to z.
• Traverse the string and mark letters as present.
• Check if all letters are marked.

class GFG {
    static int size = 26;
    static boolean isLetter(char ch) {
        return Character.isLetter(ch);
    }
    static boolean allLetter(String str, int len) {
        str = str.toLowerCase();
        boolean[] present = new boolean[size];

        for (int i = 0; i < len; i++) {
            if (isLetter(str.charAt(i))) {
                int index = str.charAt(i) - 'a';
                present[index] = true;
            }
        }

        for (int i = 0; i < size; i++) {
            if (!present[i])
                return false;
        }
        return true;
    }

    public static void main(String[] args) {
        String str = "Abcdefghijklmnopqrstuvwxyz";
        if (allLetter(str, str.length()))
            System.out.println("Yes");
        else
            System.out.println("No");
    }
}

Yes

Explanation:

• isLetter() checks whether the current character is an alphabet.
• allLetter() converts the string to lowercase for case-insensitive checking.
• A boolean[] present array stores whether each letter from a to z appears in the string.
• Each character is mapped to an index using ch - 'a' and marked as true.
• The array is checked to ensure no letter is missing.

2. Using Character Traversal

• Convert the string to lowercase.
• Loop from 'a' to 'z'.
• Check if each letter exists in the string using contains().
• If any letter is missing, print No.

class GFG {
    static void allLetter(String str) {
        str = str.toLowerCase();
        boolean allPresent = true;

        for (char ch = 'a'; ch <= 'z'; ch++) {
            if (!str.contains(String.valueOf(ch))) {
                allPresent = false;
                break;
            }
        }
        if (allPresent)
            System.out.println("Yes");
        else
            System.out.println("No");
    }

    public static void main(String[] args) {
        String str = "Abcdefghijklmnopqrstuvwxyz12";
        allLetter(str);
    }
}

Yes

Explanation:

• The string is converted to lowercase to ignore case differences.
• A boolean variable allPresent assumes all letters are present initially.
• A loop runs from 'a' to 'z' to check every alphabet letter.
• str.contains() checks whether each letter exists in the string.
• If any letter is missing, allPresent is set to false and the loop stops.