VirtoolsTranslation/NlpParser/MainRunner.java

import org.antlr.v4.runtime.*;
import org.antlr.v4.runtime.tree.*;

import java.io.FileOutputStream;
import java.io.FileInputStream;
import java.io.OutputStreamWriter;
import java.nio.charset.StandardCharsets;
import java.nio.charset.Charset;

public class MainRunner {

	private static void printHelp() {
		System.out.println("NlpParser Usage");
		System.out.println("NlpParser <src> <dest>");
		System.out.println();
		System.out.println("<src>  - the decoded NLP text file.");
		System.out.println("<dest> - the output json file.");
	}

	private static class UserRequest {
		public UserRequest(String input_filepath, String output_filepath) {
			this.mInputFilePath = input_filepath;
			this.mOutputFilePath = output_filepath;
		}

		String mInputFilePath;
		String mOutputFilePath;

		public String getInputFilePath() {
			return this.mInputFilePath;
		}

		public String getOutputFilePath() {
			return this.mOutputFilePath;
		}

	}

	private static UserRequest resolveArguments(String[] args) throws Exception {
		// Check parameter
		if (args.length != 2) {
			throw new Exception("Invalid arguments count!");
		}
		// Return fetched argumnts
		return new UserRequest(args[0], args[1]);
	}

	private static void executeWorker(UserRequest user_request) throws Exception {
		// Use try-with-resources to safely manage file stream.
		try (FileInputStream fin = new FileInputStream(user_request.getInputFilePath());
				FileOutputStream fout = new FileOutputStream(user_request.getOutputFilePath());
				OutputStreamWriter fw = new OutputStreamWriter(fout, StandardCharsets.UTF_8);) {
			// Start lex and parse
			CharStream input = CharStreams.fromStream(fin, Charset.forName("windows-1252"));
			NlpLexer lexer = new NlpLexer(input);
			CommonTokenStream tokens = new CommonTokenStream(lexer);
			NlpParser parser = new NlpParser(tokens);

			// Walk tree to build json
			ParseTree tree = parser.document();
			ParseTreeWalker walker = new ParseTreeWalker();
			JsonConverter converter = new JsonConverter();
			walker.walk(converter, tree);

			// Write json
			fw.write(converter.buildJsonString());
		}
	}

	public static void main(String[] args) throws Exception {
		// Check argument
		UserRequest user_request = null;
		try {
			user_request = resolveArguments(args);
		} catch (Exception e) {
			System.out.print("[Argument Error] ");
			System.out.println(e.getMessage());
			printHelp();
			return;
		}

		// Call converter
		try {
			executeWorker(user_request);
		} catch (Exception e) {
			System.out.print("[Converter Error] ");
			System.out.println(e.getMessage());
			return;
		}
	}
}