Java design Pattern--Singleton mode

Take a question to see a singleton pattern

1. What is a singleton mode?

2. What is the use of single-case mode?

3, how to achieve a single case mode?

/**

* A hungry man mode

*/

public class Singletonhungry () {

Private Singletonhungry () {}

private static Singletonhungry singleton=new singletonhungry ();

public static Singletonhungry Newsingleton () {

return singleton;

}

}

/**

* Lazy Mode

*/

public class Singletonfull () {

Private Singletonfull () {}

private static Singletonfull Singleton=null;

public static Singletonfull Newsingleton () {

if (singleton ==null)

Singleton = new Singletonfull ();

return singleton;

}

}

Note the difference: 1, efficiency issues

2. Thread safety issues

Java design Pattern--Singleton mode