Effective Java--1)Create/Destroy Object: static factory method

Static factory method

Static factory is another way to create a class instance other than constructor. [1] shows an example:

 public static Boolean valueOf(boolean b){  
   return b? Boolean.TRUE:Boolean.FALSE;  
 }  

Static factory is a special kind of static method. Static factory returns a class instance.
Pros:

• Static factory has name. Constructor doesn't have name, sometimes may call the wrong constructor.
• Do not require to create a new object each time they are invoked.
• Like Flyweight technique, greatly improve performance if equivalent objects are requested often, especially when they are expensive to create.
• Can return any subtype of their return type.
• Like EnumSet returns a single long if no more than 65 elements; otherwise backs a long array.
• Static factory reduces the verbosity of creating parameterized type instance.
• Constructor flavor:

   public static Boolean valueOf(boolean b){  
     return b? Boolean.TRUE:Boolean.FALSE;  
   }  
  

• Static factory method flavor:

  
  Map<String,List<String>> m = HashMap.newInstance();
  public static <K,V> HashMap<K,V> newInstance(){ return new HashMap<K,V>;}
  

Cons:

• Class without public/protected constructor cannot be subclassed.
• Not really distinguishable from other static method.

On the way to my dream,tick-tock,tick-tock~~

For such a long time, I have struggled to fit in the "best" life. I tried the best to adjust external changes. I don't always complain about that. But, it is easy to fall in sadness. I don't want to live in that way any more.

I want to live my own life not belong to anyone else. I love the movie "Sydney White". I love the way they treat life and face themselves. They could speak loudly that "I'm a dork". Why cannot I face my flaws and then find my lengths. I should do that, right now.

I want to become an excellent software engineering. I want to have my puppy.

I will find my dream work and dream company. Not just from the top ranking.

I have acnes and fight with them. I dream of being a dog walker and comic drawer.

I love Hulk. Pretty much. "I'm always angry~~". Lalala~~~ :)

Feel the light in my heart and listen to my self. Thanks ooh. Thanks Home. I love comic. There's no one else could help me but myself.