enum Sex
{
    Male, Female;
}

class Head
{

}

// ignore other class implementation

class Human
{
    private String          name;
    private Sex             sex;
    private Head            head;
    private Body            body;
    private Arm             arm;
    private Leg             leg;
    
    // getter and setter methods.
    
    // A human can speak
    public void speak()
    {
    }
    
    // A human can walk
    public void walk()
    {
    }
    
    // A human can sleep
    public void sleep()
    {
    }
}

enum Sex
{
    Male, Female;
}

class Head
{

}

// ignore other class implementation

class Human
{
    private static God      god;
    
    private String           name;
    private Sex             sex;
    private Head            head;
    private Body            body;
    private Arm            arm;
    private Leg             leg;
    
    // getter and setter methods.
    
    // A human can speak
    public void speak(String words)
    {
        if (words.equals("I don't believe in God'"))
        {
            god.punishHuman(this);
        }
    }
    
    // A human can eat
    public void eat(boolean ifPrayFirst)
    {
        if (ifPrayFirst)
        {
            god.giveMoreFood(this);
        }
        else
        {
            god.eatMySelf(this);
        }
    }
    
    // A human can sleep
    public void sleep(boolean ifPrayFirst)
    {
        if (ifPrayFirst)
        {
            god.letSleepWell(this);
        }
        else
        {
            god.giveOneNightmare(this);
        }
    }
}

skwujinhua wrote:
JiafanZhou﹐Short and sweet, I'm sure! This analogy is very exciting.
But my English is very poor ,so let me speaking Chinese.
我懂你說的意思﹐也知道操作Statis 方法或變量﹐但在程序中如果過多的使用Static﹐會有什么后果或優點呢?

JiafanZhou wrote:
Recently I have been preparing for the SCBCD exam, and I found the EJB3.0 specification is very very strict about using the static fields/members for the session and message-driven beans.

It also proves the concept that using static is not thread-safe, I believe this is the reason for the EJB3.0 specification.

Quoted from the EJB 3.0 specification.

A field or method of a bean class may be annotated to request that an entry from the bean's environment be injected. Any of the types of resources or other environment entries described may be injected. Injection may also be requested using entries in the deployment descriptor corresponding to each of these resource types.

The field or method MAY have any access qualifier, but <u>MUST NOT</u> be static.

In other words, EJB experts have the same concerns like me that using static fields could seriously compromise the thread safety.

Regards,
Jiafan