32 lines
941 B
Java
32 lines
941 B
Java
Writing a Thread-Safe Singleton
|
|
|
|
public class JGKSingleton
|
|
{
|
|
/* Here is the instance of the Singleton */
|
|
private static JGKSingleton instance_;
|
|
/* Need the following object to synchronize */
|
|
/* a block */
|
|
private static Object syncObject_;
|
|
/* Prevent direct access to the constructor*/
|
|
private JGKSingleton()
|
|
{
|
|
super();
|
|
}
|
|
public static JGKSingleton getInstance()
|
|
{
|
|
/* in a non-thread-safe version of a Singleton the following line could be executed, and the */
|
|
/* thread could be immediately swapped out */
|
|
if (instance_ == null)
|
|
{
|
|
synchronized(syncObject_)
|
|
{
|
|
if (instance_ == null)
|
|
{
|
|
instance_ = new JGKSingleton();
|
|
}
|
|
}
|
|
}
|
|
return instance_;
|
|
}
|
|
}
|