MarkdownParse.java

//https://howtodoinjava.com/java/io/java-read-file-to-string-examples/

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.ArrayList;

public class MarkdownParse {

    public static ArrayList<String> getLinks(String markdown) {
        ArrayList<String> toReturn = new ArrayList<>();
        // find the next [, then find the ], then find the (, then read link upto next )
        int currentIndex = 0;
        while(currentIndex < markdown.length()) {
            int openBracket = markdown.indexOf("[", currentIndex);

            if (openBracket == -1) break;

            while (markdown.charAt(openBracket == 0 ? openBracket : openBracket - 1) == '!' || 
                markdown.charAt(openBracket == 0 ? openBracket : openBracket - 1) == '\\') {
                openBracket = markdown.indexOf("[", openBracket + 1);

                if (openBracket == -1) break;
            }


            int closeBracket = markdown.indexOf("]", openBracket);
            int openParen = markdown.indexOf("(", closeBracket);
            while (openParen < markdown.length() && markdown.charAt(openParen + 1) == '(') {
                openParen += 1;
            }
            int closeParen = markdown.indexOf(")", openParen);

            if (openBracket == -1 || closeBracket == -1 || openParen == -1 || closeParen == -1) break;

            if (openParen == closeBracket+1) toReturn.add(markdown.substring(openParen + 1, closeParen));
            currentIndex = closeParen + 1;
        }

        return toReturn;
    }


    public static void main(String[] args) throws IOException {
        Path fileName = Path.of(args[0]);
        String content = Files.readString(fileName);
        ArrayList<String> links = getLinks(content);
	    System.out.println(links);
        // change

    }
}