package com.duplxey.nquiz.util;

import java.util.EnumSet;

public class EnumUtil {

    /**
     * Checks if the given value exists in the enumeration class.
     *
     * @param _enumClass  Enum class
     * @param value  Value
     * @param <E>  /
     * @return  True if exists
     */
    public static <E extends Enum<E>> boolean isValid(Class<E> _enumClass, String value) {
        try {
            return EnumSet.allOf(_enumClass).contains(Enum.valueOf(_enumClass, value));
        } catch (Exception e) {
            return false;
        }
    }
}

package com.duplxey.nquiz.util;

import java.io.*;
import java.util.stream.Collectors;

public class FileUtil {

    /**
     * Gets the file's content as a string.
     *
     * @param path  File's path
     * @return  Content
     */
    public static String getFileContent(String path) {
        StringBuilder builder = new StringBuilder();
        try {
            BufferedReader br = new BufferedReader(new FileReader(path));
            String line;
            while ((line = br.readLine()) != null) {
                builder.append(line).append("\n");
            }
            br.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return builder.toString();
    }

    /**
     * Replaces the file's content with the given string.
     *
     * @param path  File's path
     * @param content  Content
     */
    public static void writeToFile(String path, String content) {
        try {
            BufferedWriter writer = new BufferedWriter(new FileWriter(path));
            writer.write(content);
            writer.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * Reads the given resource file as a string.
     *
     * @param fileName the path to the resource file
     * @return the file's contents or null if the file could not be opened
     */
    public static String getResourceContent(String fileName) {
        InputStream is = FileUtil.class.getClassLoader().getResourceAsStream(fileName);
        if (is != null) {
            BufferedReader reader = new BufferedReader(new InputStreamReader(is));
            return reader.lines().collect(Collectors.joining(System.lineSeparator()));
        }
        return null;
    }
}

package com.duplxey.nquiz.util;

import com.google.gson.Gson;

/**
 * Singleton for Gson
 * (I couldn't find anything in the documentation clarifying that you should share the instance of gson or create a new one every time)
 */
public class GsonUtil {

    private Gson gson;
    private static GsonUtil instance;

    public static GsonUtil getInstance() {
        if (instance == null) {
            instance = new GsonUtil();
        }
        return instance;
    }

    private GsonUtil() {
        gson = new Gson();
    }

    public Gson getGson() {
        return gson;
    }
}