如何删除括号中的所有空格，注释，多余的行和信息？

Question

我已经为cps类完成了这个项目，并且已经设置了扫描仪和打印书写器以及所有其他东西，但我需要摆脱括号中的所有空格，注释，多余的行和信息。我不知道如何去做。我的工作是在下面，我尝试过.replaceall和每个字符的if语句，但是我没有用。谢谢您的帮助。

import java.util.Scanner;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintWriter;

/*
 * @author wrigh4d
 * Date: 11/7/19
 * Description:  Takes instruction from SumN and then prints it into output.txt 
 */

public class InstructionExtractor {

    public static void main(String[] args) throws FileNotFoundException {
        //Sets up Scanner/Print Writer and declares variable
        File myFile = new File("sumN.txt");
        Scanner sc = new Scanner(myFile);

        File outputFile = new File("output.txt");
        PrintWriter pw = new PrintWriter(outputFile);

        String currentLine = "";

        //Sets up while loop to read in each line
        while(sc.hasNextLine()) {
            currentLine = sc.nextLine();    //Sets each line to currentLine
            currentLine = processLine(currentLine); //Takes currentLine down to processLine
            if(currentLine != "") { //if there is something inside of current Line it appends it to printwriter
                pw.append(currentLine + "\n");
            }

        }

        pw.flush(); //prints onto output.txt

    }

    public static String processLine(String currentLine) {
        //Gets rid of whitespace inside of currentLine
        String a = currentLine.replaceAll("\\s+","");
        System.out.println(a);

        return a;

    }

}