Is there a way to get rid of accents and convert a whole string to regular letters?

Processing logic: Dissection and Deletion

String noAccents = Normalizer.normalize(input, Normalizer.Form.NFD)  // "Dissect" the string
                   .replaceAll("\\p{M}", "");  // "Delete" the accents
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Normalizer class allows you to normalize any unicode text. With different forms available, we choose NFD, as it decomposes accented characters into their base form and diacritical marks. By using a regular expression \\p{M}, we match all diacritic marks and remove them.

Optimization for higher performance

Although replaceAll() works, it might not be the ideal choice when processing big documents due to its efficiency. That's when handling characters directly by using character arrays or applying translation tables comes into play, optimizing the performance. Imagine it as going on a highway avoiding traffic lights.

Mind the language context

Before deploying your accent removal process, you must consider the linguistic implications. Certain non-Latin scripts such as Russian and Chinese don't use accents in the way the Latin alphabet does. Stripping characters might rob your text off its original meaning. So, make sure to localize before you sanitize.

Advanced accent removal techniques

Detailed coverage with Apache Commons

Although the Normalizer serves you well, it may fall short in presence of special characters without a decomposed form or peculiar cases. Fear not! You can rely on Apache Commons Lang which offers utility method StringUtils.stripAccents(input) to handle most of these cases. Guess what, it's as smooth as Sinead O’Connor’s head.

Performance paired with Character Array

If you've got a need for speed, working with char[] arrays can take your code from a Ford Fiesta to a Ferrari. Here's how you do it:

char[] charArray = input.toCharArray(); // Convert string to char array
StringBuilder sb = new StringBuilder(input.length()); // Prepare a builder for your output
 
for (char c : charArray) {     // loop over every character
    char mappedChar = translationTable.getOrDefault(c, c);  // fetch the normal character
    sb.append(mappedChar); // build the string
}

String noAccents = sb.toString(); // convert back to the string
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This is like being your own postman. You know where the letterboxes are, so why not deliver the letters yourself.

Rapid performance with Translation Tables

If you're dealing with known input range, like languages from Latin1 or Latin2, using the translation table method can be a massive performance boost. A static char[] array acts as a go-to table to quickly map accented characters to unaccented ones. This can make a lot of difference in large text bodies.

Improving your solution: Testing and Refinement

Testing with various string types and languages ensures your method is robust. Cover the following cases:

• Strings with multiple accents.
• Strange and uncommon characters.
• Massive text to benchmark performance.

Dive into regular-expressions.info and Unicode Consortium resources for an excellent understanding of Unicode characters and Java handling. The knowledge can save you a surprising amount of headache or even an aspirin.