package seedu.emeraldo.commons.core;

/**
 * Container for user visible messages.
 */
public class Messages {

    public static final String MESSAGE_UNKNOWN_COMMAND = "Unknown command";
    public static final String MESSAGE_INVALID_COMMAND_FORMAT = "Invalid command format! \n%1$s";
    public static final String MESSAGE_INVALID_TASK_DISPLAYED_INDEX = "The task index provided is invalid";
    public static final String MESSAGE_TASKS_LISTED_OVERVIEW = "%1$d tasks listed!";

}

package seedu.emeraldo.commons.core;

import seedu.emeraldo.logic.commands.HelpCommand;

/**
 * Container for user visible messages.
 */
public class Messages {

    public static final String MESSAGE_UNKNOWN_COMMAND = "Unknown command!\n"
    		+ HelpCommand.MESSAGE_USAGE;
    public static final String MESSAGE_INVALID_COMMAND_FORMAT = "Invalid command format! \n%1$s";
    public static final String MESSAGE_INVALID_TASK_DISPLAYED_INDEX = "The task index provided is invalid";
    public static final String MESSAGE_TASKS_LISTED_OVERVIEW = "%1$d tasks listed!";

}

Change message when an unknown command word is input