How to Efficiently Determine if a String Contains Only Letters?

How to Check if a String Contains Only Letters

To determine if a string consists exclusively of letters, we need to employ a specific evaluation process.

There are two primary approaches to tackle this task: speed-oriented and simplicity-focused.

Speed Optimization

The speed-based method involves a loop-based traversal of the string characters. Each character is scrutinized using the Character.isLetter() method. If a non-letter character is encountered, the function immediately returns false. Otherwise, it returns true after examining all characters.

public boolean isAlpha(String name) {
    char[] chars = name.toCharArray();

    for (char c : chars) {
        if(!Character.isLetter(c)) {
            return false;
        }
    }

    return true;
}

Simplicity Prioritization

If simplicity is the paramount concern, a concise RegEx-based approach can be employed. The name.matches("[a-zA-Z] ") expression examines the string using a regular expression. It checks if the entire string consists of one or more consecutive letters, either uppercase or lowercase. If the expression evaluates to true, the string contains only letters; otherwise, it does not.

public boolean isAlpha(String name) {
    return name.matches("[a-zA-Z]+");
}

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