java类没有任何方法，但在static关键字下包含逻辑

Question

我对以下代码片段有几个疑问:

public class Configuration
{
    public static String TEMP_DIR;
    public static List<String> LEvents;
    ......//some more public static members......

   static{
      //logic to fill all the members of this class
    }
}

1. 我想知道填充成员的逻辑什么时候执行？
2. 如果我使用实际的静态方法来执行逻辑并调用一次，这种方法是否有所不同？

Answer 1

static {
    //logic to fill all the members of this class
} 

代码被称为 static initializer .

I am wondering when will the logic which fills the members be executed?

Java 语言规范说

A static initializer declared in a class is executed when the class is initialized (§12.4.2).

然后你问

And is this approach different if i would have used actual static method to execute the logic and call it once?

使用静态初始化程序，JVM 负责执行代码。使用静态方法，您必须自己调用它。为了使其等效，您可能还想保证该方法仅被调用/执行一次。