static void Main(string[] args)
{
/* Example 1
* Initialize _instance when starting to run the program.
* Defect: wasting when not in use or unused.
*/
#region Singleton Example 1
SingletonExample1.GetInstance().Hello();
Console.WriteLine("");
#endregion
/* Example 1
* Only initialize _instance when calling the GetInstance function for the first time.
* Defect: possiple to create multiple _instance when there are multiple thread
*/
#region Singleton Example 2
var thread1 = new Thread(() => {
SingletonExample2.GetInstance().Hello();
});
var thread2 = new Thread(() => {
SingletonExample2.GetInstance().Hello();
});
thread1.Start();
thread2.Start();
#endregion
/* Example 1
* Only initialize _instance when calling the GetInstance function for the first time.
*
*/
#region Singleton Example 3
var thread3 = new Thread(() => {
SingletonExample3.GetInstance().Hello();
});
var thread4 = new Thread(() => {
SingletonExample3.GetInstance().Hello();
});
thread3.Start();
thread4.Start();
#endregion
Console.ReadKey();
}
public static SingletonExample3 GetInstance()
{
if (_instance == null)
{
lock (lockObject)
{
if (_instance == null)
{
Random rd = new Random();
_instance = new SingletonExample3(rd.Next(18, 23));
}
}
}
return(_instance);
}
