symboltable.java

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Scanner;

public class Test {
    private static ArrayList<String> operators = new ArrayList<>();
    private static ArrayList<String> keywords = new ArrayList<>();
    private static ArrayList<String> symbols = new ArrayList<>();
    private static ArrayList<String> variables = new ArrayList<>();
    private static ArrayList<String> constants = new ArrayList<>();
    private static List<String> operatorList;
    private static List<String> keywdsList;
    private static List<String> symblsList;
    private static Scanner scanner = new Scanner(System.in);

    public static void main(String[] args) {
        initStoredItems();
        System.out.print("Input String: ");
        String input = scanner.nextLine();
        String[] tokens = generateTokens(input);
        for (String str : tokens
             ) {
            if (operatorList.contains(str)) operators.add(str); 
            else if (keywdsList.contains(str)) keywords.add(str);
            else if (symblsList.contains(str)) symbols.add(str); 
            else if (str.matches("[\\d]+")) constants.add(str); 
            else variables.add(str);
        }
        System.out.println("Operators: "+operators);
        System.out.println("Symbols: "+symbols);
        System.out.println("Keywords: "+keywords);
        System.out.println("Variables: "+variables);
        System.out.println("Constants: "+constants);

    }
    private static void initStoredItems(){
        String[] storedKeywds = new String[]{"for","if","while","do","break","int"};
        String[] storedOperators = new String[]{"+","-","*","/","="};
        String[] storedSymbls = new String[]{";","==","!"};
        operatorList = Arrays.asList(storedOperators);
        keywdsList = Arrays.asList(storedKeywds);
        symblsList = Arrays.asList(storedSymbls);

    }

    private static String[] generateTokens(String input){
        String[] tokens = input.split("[\\s]+");
        return tokens;
    }
}