How to process a String with regexes in Java?

[swuster]

I'm attempting to write a relatively simple method. It needs to search through a String for any characters that are not specifically 'A', 'I', 'O', and 'C', returning false if it runs across any other characters besides those four. The string I'm processing could be hundreds/thousands of characters long, so I'm trying to avoid using a loop if possible.

I know that I can use a regular expression like [^AIOC] to do this but I'm not sure how. Class String has a method matches() which accepts a regex String as an argument but I believe it only matches the entire string and not the individual characters. Am I doing it wrong? Appreciate the feedback.

Thinking of using something like this, except I know that matches doesn't work that way. I need something more like find():
public boolean checkLine(String line) {
return !(line.matches("[^ACIO]"));
}

 

[Valkarie]

You could use a combination of the matches() method and the find() method of java.util.regex.Matcher.First, you can use the matches() method to check if the entire string contains any characters that are not A, I, O, or C by using this regular expression:String pattern = "^[AIOC]+$";boolean valid = str.matches(pattern);If the matches() returns false, then it means that the string contains at least one character that is not A, I, O, or C.If it returns true, then you can use the find() method to search for specific characters. You can use this regular expression to search for characters that are not A, I, O, or C:String pattern = "[^AIOC]";Matcher m = Pattern.compile(pattern).matcher(str);boolean valid = !m.find();If the find() method returns true, then it means that the string contains at least one character that is not A, I, O, or C.Putting it all together, you can use the following method to check if a String contains only A, I, O, and C characters:public boolean checkLine(String line) { String pattern = "^[AIOC]+$"; if (!line.matches(pattern)) { return false; } pattern = "[^AIOC]"; Matcher m = Pattern.compile(pattern).matcher(str); return !m.find();}

 

[Mene]

I would recommend using the Pattern and Matcher classes in Java to process the String with regexes. These classes allow for more flexibility and control in searching for patterns within a String.

Here is an example of how you could use these classes to achieve your desired result:

import java.util.regex.Pattern;
import java.util.regex.Matcher;

public boolean checkLine(String line) {
// create a regex pattern to match any characters that are not 'A', 'I', 'O', or 'C'
Pattern pattern = Pattern.compile("[^AIOC]");
// create a matcher object to search for the pattern in the given String
Matcher matcher = pattern.matcher(line);
// use the find() method to search for the pattern within the String
if (matcher.find()) {
// if the pattern is found, return false
return false;
} else {
// if the pattern is not found, return true
return true;
}
}

This method uses the find() method instead of the matches() method, which allows for searching for the pattern within the String instead of just checking if the entire String matches the pattern.

I would also recommend adding comments to your code to make it more clear and readable for others who may need to use it in the future.