java 初始化による初期化

Posted 2021-05-08

class User{
  private String name;
  private int count;
  static{
    User.count = 0;
    System.out.println("static initializer");
  }
  {
    System.out.println("instance initializer");
  }
  public class User(String name){
    this.name = name;
    User.count++;
    System.out.println("constructor");
  }
  public static void getInfo(){
    System.out.println("# of instances: "+User.count);
  }
}
public class MyInitializer{
 public static void main(String[] args){
   User.getInfo();
   User.getInfo();
   User tom = new User("tom");
   User.getInfo();
   User bob = new User("bob");
   User.getInfo();
  }    
}