Java 非静态初始化的例子

public class ExA {
  static {
    System.out.println("父类--静态代码块");
  }
 
  public ExA() {
    System.out.println("父类--构造函数");
  }
 
  {
    //非静态代码块
    System.out.println("父类--非静态代码块");
  }
 
  public static void main(String[] args) {
    new ExB();
  }
}
 
class ExB extends ExA {
  static {
    System.out.println("子类--静态代码块");
  }
  {
    //非静态代码块
    System.out.println("子类--非静态代码块");
  }
 
  public ExB() {
    System.out.println("子类--构造函数");
  }
}

class Mug{
  public Mug(int marker) {
    System.out.println("Mug("+marker+")");
  }
  void f(int marker){
    System.out.println("f("+marker+")");
  }
}
public class Mugs {
  Mug mug1;
  Mug mug2;
   
  {
    //非静态代码块
    mug1 = new Mug(1);
    mug2 = new Mug(2);
    System.out.println("mug1 & mug2 initialized");
  }
  Mugs(){
    System.out.println("Mugs()");
  }
   
  Mugs(int i){
    System.out.println("Mugs(int i)");
  }
   
  public static void main(String[] args) {
    System.out.println("Inside main()");
    //首先执行Mugs类中非静态代码块，创建两个对象。然后执行无参构造函数
    new Mugs();
    System.out.println("new Mugs() completed");
    //再执行Mugs类中非静态代码块，这也是和静态代码块只初始化一次的不同之后，其次调用有参构造函数
    new Mugs(1);
    System.out.println("new Mugs(1) completed");
  }
 
}