Assembler Pass 2

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileWriter;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.StringTokenizer;

import java.util.*;
    class Tuple {
        //m_class specifies class of the mnemonic such as IS, DL, or AD
        String mnemonic, m_class, opcode;
        int length;

        Tuple() {}

        Tuple(String s1, String s2, String s3, String s4) {
            mnemonic = s1;
            m_class = s2;
            opcode = s3;
            length = Integer.parseInt(s4);

        }
    }

    class SymTuple {
        String symbol, address, length;

        SymTuple(String s1, String s2, String i1) {
            symbol = s1;
            address = s2;
            length = i1;
        }
    }

    class LitTuple {
        String literal, address, length;

        LitTuple() {}

        LitTuple(String s1,  String s2, String i1) {
            literal = s1;
            address = s2;
            length = i1;
        }
    }

    public class Assembler_PassTwo {

    static int lc,iSymTabPtr=0, iLitTabPtr=0, iPoolTabPtr=0;
    static int poolTable[] = new int[10];
    static Map<String,Tuple> MOT;
    static ArrayList<SymTuple> symtable;
    static ArrayList<LitTuple> littable;
    static Map<String, String> regAddressTable;
    static PrintWriter out_pass2;

    static void initiallizeTables() throws Exception{
        symtable = new ArrayList<>();
        littable = new ArrayList<>();
        regAddressTable = new HashMap<>();
        //MOT = new HashMap<>();
        String s;
        BufferedReader br;
        br = new BufferedReader(new InputStreamReader(new FileInputStream("/home/student/Downloads/PASS I ASSEMBLER-20240710T090734Z-001/PASS II ASSEMBLER/Assembler_PassTwo/symtable.txt")));
        while((s = br.readLine()) != null) {
            StringTokenizer st = new StringTokenizer(s, "\t", false);
            symtable.add(new SymTuple(st.nextToken(), st.nextToken(), ""));
        }
        br.close();
        br = new BufferedReader(new InputStreamReader(new FileInputStream("/home/student/Downloads/PASS I ASSEMBLER-20240710T090734Z-001/PASS II ASSEMBLER/Assembler_PassTwo/littable.txt")));
        while((s = br.readLine()) != null) {
            StringTokenizer st = new StringTokenizer(s, "\t", false);
            littable.add(new LitTuple(st.nextToken(), st.nextToken(), ""));
        }
        br.close();
        //Initiallize register address table
        regAddressTable.put("AREG", "1");
        regAddressTable.put("BREG", "2");
        regAddressTable.put("CREG", "3");
        regAddressTable.put("DREG", "4");
    }

    static void pass2() throws Exception{
        BufferedReader input = new BufferedReader(new InputStreamReader(new FileInputStream("/home/student/Downloads/PASS I ASSEMBLER-20240710T090734Z-001/PASS II ASSEMBLER/Assembler_PassTwo/output_pass1.txt")));
        out_pass2 = new PrintWriter(new FileWriter("/home/student/Downloads/PASS I ASSEMBLER-20240710T090734Z-001/PASS II ASSEMBLER/Assembler_PassTwo/output_pass2.txt"), true);
        String s;

        //Read from intermediate file one line at a time
        while((s = input.readLine()) != null) {
            //Replace all ( and ) characters by a blank string
            s=s.replaceAll("(\\()", " ");
            s=s.replaceAll("(\\))", " ");

            //For each line, separate out the tokens
            String ic_tokens[] = tokenizeString(s, " ");
            if(ic_tokens == null || ic_tokens.length==0){
                continue;
            }
            String output_str = "";

            //Second token contains mnemonic class and opcode
            String mnemonic_class = ic_tokens[1];
            //Separate the mnemonic and its opcode which are separated by a comma
            String m_tokens[] = tokenizeString(mnemonic_class, ",");

            //Write the second token as is in the output file

            if(m_tokens[0].equalsIgnoreCase("IS")){
                //First token is location counter which will be output as it is
                output_str += ic_tokens[0] + " ";
                //Output the opcode of the instruction
                output_str += m_tokens[1] + " ";
                String opr_tokens[];
                for(int i = 2; i <ic_tokens.length; i++){
                    opr_tokens = tokenizeString(ic_tokens[i], ",");
                    if(opr_tokens[0].equalsIgnoreCase("RG")){
                        output_str += opr_tokens[1] + " ";
                    }
                    else if(opr_tokens[0].equalsIgnoreCase("S")){
                        int index = Integer.parseInt(opr_tokens[1]);
                        output_str += symtable.get(index).address + " ";
                    }
                    else if(opr_tokens[0].equalsIgnoreCase("L")){
                        int index = Integer.parseInt(opr_tokens[1]);
                        output_str += littable.get(index).address + " ";
                    }
                }
            }
            else if(m_tokens[0].equalsIgnoreCase("DL")){
                //First token is location counter which will be output as it is
                output_str += ic_tokens[0] + " ";
                if(m_tokens[1].equalsIgnoreCase("02")){
                    //Process for operands of mnemonic DC
                    String opr_tokens[] = tokenizeString(ic_tokens[2], ",");
                    output_str += "00 00 " + opr_tokens[1] + " ";
                }
            }
            System.out.println(output_str);
            out_pass2.println(output_str);

        }
    }

    static String[] tokenizeString(String str, String separator){
        StringTokenizer st = new StringTokenizer(str, separator, false);
        //Construct an array of the separated tokens
        String s_arr[] = new String[st.countTokens()];
        for(int i=0 ; i < s_arr.length ; i++) {
            s_arr[i] = st.nextToken();
        }
        return s_arr;
    }
    public static void main(String[] args) throws Exception {
        initiallizeTables();
        pass2();
    }
}