Posted on 2006-07-09 12:42
Jedi 閱讀(303)
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Design Patterns
public
?
class
?Singleton?{
????
private
?
volatile
?
static
?Singleton?uniqueInstance;
????
private
?Singleton(){
????????
????}
????
????
public
?
static
?Singleton?getInstance(){
????????
if
(uniqueInstance
==
null
){
????????????
synchronized
(Singleton.
class
){
????????????????
if
(uniqueInstance
==
null
){
????????????????????uniqueInstance?
=
?
new
?Singleton();
????????????????}
????????????}
????????}????????
????????
return
?uniqueInstance;?
????}
}
1. private constructor
2. static getInstance
3. syncronized..waste a lot of time
4. double check..modified syncronize, so time-waste might occurs only when first time the instance construct