Static initialization block and initializer block

Static initialization block在類別載入時會執行該區塊中的程式碼, 而且整個程式的執行過程中只會執行一次.

Initializer block則是在每個物件被建立時執行該區塊中的程式碼, 接著才執行contructor中的程式碼.

class ClassA {
    // static initialization block
    static {
        System.out.println("This is static initialization blocks");
    }

    // initializer block
    {
        System.out.println("This is initializer block");
    }

    public ClassA()
    {
        System.out.println("Constructor A");
    }

    public void print()
    {
        System.out.println("I am A");
    }

    public static void staticPrint()
    {
        System.out.println("Static print");
    }
}

public class Test01 {
    public static void main(String[] args) {
        System.out.println("Start testing...");
        ClassA.staticPrint();
        ClassA a = new ClassA();
        a.print();
    }
}