solved the problem

TrelloMachingCoding/src/com/machine/coding/CommandExecutor.java

@@ -0,0 +1,170 @@
+package com.machine.coding;
+
+import com.machine.coding.common.ServiceFactory;
+import com.machine.coding.model.Board;
+import com.machine.coding.model.Card;
+import com.machine.coding.model.CardList;
+import com.machine.coding.service.BoardService;
+import com.machine.coding.service.CardListService;
+import com.machine.coding.service.CardService;
+
+@SuppressWarnings("unchecked")
+public class CommandExecutor {
+
+	// TODO : Change it to interface later.
+	private BoardService<String, Board> boardService = (BoardService) ServiceFactory.getService("BOARD_SERVICE");
+	private CardListService<String, CardList> cardListService = (CardListService) ServiceFactory
+			.getService("CARDLIST_SERVICE");
+	private CardService<String, Card> cardService = (CardService) ServiceFactory.getService("CARD_SERVICE");
+
+	public void execute(String inputCommand) {
+		String[] commands = inputCommand.split(" ");
+		switch (commands[0]) {
+		// BOARD.
+		case "BOARD":
+			switch (commands[1]) {
+			case "CREATE":
+				boardService.create(new Board(commands[2]));
+				break;
+
+			case "DELETE":
+				boardService.delete(commands[2], true);
+				break;
+
+			default:
+				switch (commands[2]) {
+				case "ADD_MEMBER":
+					boardService.addMember(commands[1], commands[3]);
+					break;
+
+				case "REMOVE_MEMBER":
+					boardService.removeMember(commands[1], commands[3]);
+					break;
+
+				default:
+
+					try {
+						boardService.updateField(commands[2], commands[3], commands[1]);
+					} catch (IllegalArgumentException | IllegalAccessException | NoSuchFieldException
+							| SecurityException e) {
+						e.printStackTrace();
+					}
+
+					break;
+				}
+				break;
+			}
+			break;
+
+		// List
+		case "LIST":
+			switch (commands[1]) {
+			case "CREATE":
+				CardList cardList = new CardList(commands[3]);
+				cardList.setBoard(boardService.getById(commands[2]));
+				String id = cardListService.create(cardList);
+				boardService.addCardList(commands[2], id);
+				break;
+
+			case "DELETE":
+				cardListService.delete(commands[2], true);
+				break;
+
+			default:
+				switch (commands[2]) {
+
+				default:
+
+					try {
+						cardListService.updateField(commands[2], commands[3], commands[1]);
+					} catch (IllegalArgumentException | IllegalAccessException | NoSuchFieldException
+							| SecurityException e) {
+						e.printStackTrace();
+					}
+
+					break;
+				}
+				break;
+			}
+			break;
+
+		// List
+		case "CARD":
+			switch (commands[1]) {
+			case "CREATE":
+				Card card = new Card(commands[3]);
+				card.setCardList(cardListService.getById(commands[2]));
+				String id = cardService.create(card);
+				cardListService.addCard(commands[2], id);
+				break;
+
+			case "DELETE":
+				cardService.delete(commands[2]);
+				break;
+
+			default:
+				switch (commands[2]) {
+
+				case "ASSIGN":
+					cardService.assign(commands[1], commands[3]);
+					break;
+
+				case "UNASSIGN":
+					cardService.unAssign(commands[1]);
+					break;
+
+				case "MOVE":
+					cardListService.moveCard(commands[1], commands[3]);
+					break;
+
+				default:
+
+					try {
+						cardService.updateField(commands[2], commands[3], commands[1]);
+					} catch (IllegalArgumentException | IllegalAccessException | NoSuchFieldException
+							| SecurityException e) {
+						e.printStackTrace();
+					}
+
+					break;
+				}
+				break;
+			}
+			break;
+
+		// show
+		case "SHOW":
+			String output;
+			if (commands.length == 1) {
+				output = new Formattor<Board>().format(boardService.getAll());
+				System.out.println(output);
+			} else {
+
+				switch (commands[1]) {
+				case "BOARD":
+					// Due to time constraint using toString format.
+					output = new Formattor<Board>().format(boardService.getById(commands[2]));
+					System.out.println(output);
+					break;
+				case "LIST":
+					// Due to time constraint using toString format.
+					output = new Formattor<CardList>().format(cardListService.getById(commands[2]));
+					System.out.println(output);
+					break;
+				case "CARD":
+					// Due to time constraint using toString format.
+					output = new Formattor<Card>().format(cardService.getById(commands[2]));
+					System.out.println(output);
+					break;
+
+				default:
+					break;
+				}
+			}
+			break;
+
+		default:
+			break;
+		}
+	}
+}

TrelloMachingCoding/src/com/machine/coding/Driver.java

@@ -0,0 +1,39 @@
+package com.machine.coding;
+
+import java.util.Scanner;
+
+import com.machine.coding.common.UserBase;
+import com.machine.coding.model.User;
+
+public class Driver {
+
+	public static void main(String[] args) {
+
+		CommandExecutor executor = new CommandExecutor();
+		Scanner sc = new Scanner(System.in);
+
+		createUserBase();
+
+		while (sc.hasNext()) {
+			String command = sc.nextLine();
+
+			executor.execute(command);
+
+		}
+	}
+
+	private static void createUserBase() {
+		// Creating dummy users for now , it can be created using some file or
+		// some other ways.
+		User user1 = new User("user1", "User1", "User1@gmail.com", "123");
+		User user2 = new User("user2", "User2", "User2@gmail.com", "1234");
+		User user3 = new User("user3", "User3", "User3@gmail.com", "1235");
+		User user4 = new User("user4", "User4", "User4@gmail.com", "123455");
+		UserBase.addUser(user1);
+		UserBase.addUser(user2);
+		UserBase.addUser(user3);
+		UserBase.addUser(user4);
+
+	}
+
+}

TrelloMachingCoding/src/com/machine/coding/Formattor.java

@@ -0,0 +1,25 @@
+package com.machine.coding;
+
+import java.util.List;
+
+public class Formattor<V> {
+
+	// Due to time constraint using toString format.
+	public String format(V object) {
+		if (object == null)
+			return "No Boards";
+		return object.toString();
+	}
+
+	public String format(List<V> objects) {
+		StringBuilder builder = new StringBuilder();
+		if (objects == null || objects.isEmpty())
+			return "No Boards";
+		for (V v : objects) {
+			builder.append(v.toString());
+			builder.append("\n");
+		}
+		return builder.toString();
+	}
+
+}

TrelloMachingCoding/src/com/machine/coding/common/ServiceFactory.java

@@ -0,0 +1,36 @@
+package com.machine.coding.common;
+
+import com.machine.coding.model.Board;
+import com.machine.coding.model.Card;
+import com.machine.coding.model.CardList;
+import com.machine.coding.service.BoardService;
+import com.machine.coding.service.CardListService;
+import com.machine.coding.service.CardService;
+import com.machine.coding.service.GenericService;
+
+/**
+ * @author Hakim.s
+ *
+ */
+public class ServiceFactory {
+
+	private ServiceFactory() {
+	}
+
+	@SuppressWarnings("rawtypes")
+	public static GenericService getService(String type) {
+		switch (type) {
+		case "BOARD_SERVICE":
+			return new BoardService<String, Board>();
+
+		case "CARDLIST_SERVICE":
+			return new CardListService<String, CardList>();
+		case "CARD_SERVICE":
+
+			return new CardService<String, Card>();
+		default:
+			break;
+		}
+		return null;
+	}
+}

TrelloMachingCoding/src/com/machine/coding/common/UserBase.java

@@ -0,0 +1,19 @@
+package com.machine.coding.common;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import com.machine.coding.model.User;
+
+public class UserBase {
+
+	static Map<String, User> userMap = new HashMap<String, User>();
+
+	public static User getUser(String userId) {
+		return userMap.get(userId);
+	}
+
+	public static void addUser(User user) {
+		userMap.put(user.getUserId(), user);
+	}
+}

TrelloMachingCoding/src/com/machine/coding/model/Base.java

@@ -0,0 +1,22 @@
+package com.machine.coding.model;
+
+import java.io.Serializable;
+
+public class Base implements Serializable{
+
+	/**
+	 * 
+	 */
+	private static final long serialVersionUID = 1L;
+
+	private String id;
+
+	public String getId() {
+		return id;
+	}
+
+	public void setId(String id) {
+		this.id = id;
+	}
+
+}