Tokenizer.java

import java.util.*;
import java.io.*;

class Tokenizer {

	private static List<String> keywords = new ArrayList<>();
	private static List<String> identifiers = new ArrayList<>();
	private static List<String> special = new ArrayList<>();
	private static List<String> preproc = new ArrayList<>();
	private static List<String> brackets = new ArrayList<>();
	private static List<String> values = new ArrayList<>();

	private static List<String> KEYWORDS;
	private static List<String> OPERATORS;
	private static List<String> BRAKET;

	static {
		KEYWORDS = new ArrayList<>();
		KEYWORDS.add("void");
		KEYWORDS.add("int");

		OPERATORS = new ArrayList<>();
		OPERATORS.add("+");
		OPERATORS.add("-");
		OPERATORS.add("=");

		BRAKET = new ArrayList<>();
		BRAKET.add("{");
		BRAKET.add("}");
		BRAKET.add("(");
		BRAKET.add(")");
	}

	public static void main(String args[]) throws Exception {
		File file = new File(args[0]);
		BufferedReader br = new BufferedReader(new FileReader(file));

  		String st;
		int line = 1;
		while ((st = br.readLine()) != null) {
	    	/*
		    Keywords
		    Identifiers
		    Constants
		    Strings
		    Special Symbols
		    Operators
		*/
			System.out.println("In Line #" + line + ": " + st);
			line++;
			String[] lineElements = st.trim().split(" ");

			if (lineElements[0].contains("#")) {
				String preproc = String.join("", Arrays.asList(lineElements));
				System.out.println("Preprocessor : " + preproc);
				continue;
			}

			for (int i = 0; i < lineElements.length; i++) {
				String element = lineElements[i];
				if (KEYWORDS.contains(element)) {
					keywords.add(element);
					System.out.println("Keyword : " + element);
				} else if (BRAKET.contains(element)) {
					brackets.add(element);
					System.out.println("Bracket : " + element):
				} else if (OPERATORS.contains(element)) {
					operators.add(element):
					System.out.println("Operator : " + element);
				} else if (element.matches(".*\(.*\)")) {
					identifiers.add(element.substring(0, element.indexOf("(")));
					System.out.println("Identifier : " + element.substring(0, element.indexOf("("));
				} else {
					if (element.contains(",")) {
						continue;
					}
					if (element.contains("=")) {
						operators.add("=");
						System.out.println("Operator: =");

						String subElements = element.split("=");

						identifiers.add(subElements[0]);
						System.out.println("Identifier : " + subElement[0]);

						values.add(subElements[1]);
						System.out.println("Value : " + subElements[1]);
					}
				}
			}
			/*
			for (String element : lineElements) {
				for (int i = 0; i < element.length(); i++) {
					int lastIndex = 0;
					if (element.charAt(i) == ' ' && lastIndex == 0) {
						keywords.add(element.substring(lastIndex, i));
						System.out.println("Keyword : " + element.substring(lastIndex, i));
					} else if (element.charAt(i) == '=') {
						identifiers.add(element.substring(lastIndex, i));
						System.out.println("Identifier : " + element.substring(lastIndex, i));
					} else if (element.charAt(i) == ';') {
						special.add(";");
						System.out.println("Special: ;");
						break;
					} else if (element.charAt(i) == ',') {
						special.add(",");
						System.out.println("Special : ,");
					} else if (BRAKET.contains(element.charAt(i))) {
						special.add(String.valueOf(element.charAt(i)));
						System.out.println("Bracket : " + String.valueOf(element.charAt(i)));
					}
					lastIndex = i;
				}
				*/

			}

		}
	}
}