WPF_Practice/PacticeSolution/CommandSample/ViewModels/MessageViewModel.cs

using CommandSample.Commands;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;

namespace CommandSample.ViewModels
{
    internal class MessageViewModel
    {
        public MessageCommand DisplayMessageCommand { get; set; }

        public MessageViewModel()
        {
            this.DisplayMessageCommand = new MessageCommand(DisplayMessage, AddMessage);
        }

        public void DisplayMessage(string param)
        {
            MessageBox.Show($"Clicked! (Param: {param})");
        }

        public bool AddMessage(string param)
        {
            if (string.IsNullOrEmpty(param))
                return false;

            return true;
        }
    }
}