When is the static block of a class executed?

I have 2 jars, let's call them a.jar and b.jar.

b.jar depends on a.jar.

In a.jar, I defined a class, let's call it StaticClass. In the StaticClass, I defined a static block, calling a method named "init" :

public class StaticClass {
  static {
    init();
  } 

  public void static init () {
    // do some initialization here
  }
}

in b.jar, I have a main, so in the main, I expect that the init() method has been called, but actually not. I suspect that is because the StaticClass has not been loaded by the jvm, could anyone tell me

1. Is my conclusion correct?
2. What triggers the jvm to load a class?
3. How can I get the static block executed automatically?

Thanks