public class MrHappyObject { 

private String _mood = _HAPPY; 

private final static String _HAPPY = "happy"; 
private final static String _ANNOYED = "annoyed"; 
private final static String _ANGRY = "angry"; 

public void printMood() { 
System.out.println( "I am " + _mood ); 
} 

public void receivePinch() { 
if( _mood.equals( _HAPPY ) ) { 
_mood = _ANNOYED; 
} else { 
_mood = _ANGRY; 
} 
} 

public void receiveHug() { 
if( _mood.equals( _ANGRY ) ) { 
_mood = _ANNOYED; 
} else { 
_mood = _HAPPY; 
} 
} 
}

public class MrHappyObject { 

private String _mood = _HAPPY; 

private final static String _HAPPY = "happy"; 
private final static String _ANNOYED = "annoyed"; 
private final static String _ANGRY = "angry"; 

public void printMood() { 
System.out.println( "I am " + _mood ); 
} 

public void receivePinch() { 
if( _mood.equals( _HAPPY ) ) { 
_mood = _ANNOYED; 
} else { 
_mood = _ANGRY; 
} 
} 

public void receiveHug() { 
if( _mood.equals( _ANGRY ) ) { 
_mood = _ANNOYED; 
} else { 
_mood = _HAPPY; 
} 
} 
} 

MrHappyObject obj1 = new MrHappyObject(); 
MrHappyObject obj2 = new MrHappyObject(); 

obj1.printMood(); 
obj2.printMood(); 

obj1.receiveHug(); 
obj2.receivePinch(); 

obj1.printMood(); 
obj2.printMood(); 

private static int _instantiations; 

public MrHappyObject() { 

_instantiations++; 
} 

public static int instances() { 
return _instantiations; 
} 

supertoy wrote:
以前看文章说static method的调用成本是none static method的3倍以上，从性能上不够合算，可是我自己做的实验是static method要快一些，有人能解释的清除么？

floater wrote:
I wouldn't worry about the cost in general because every optimization at this stage is *very* likely a local opt value.

I would take the approach to finish coding and testing and then do a global optimization, rather than many local optimization. Before the global optimization, there are just so many things to worry about.

I was majored in optimization when I was an under, and picked up a few sayings along the way, this is the best approach I am using. Just my two cents, of course.