this和super

package test;

public class SuperDemo {
    public static void main(String[] args) {
        Boo o=new Boo();
        Coo c=new Coo(29);
        Doo d=new Doo();
    }
}
class Coo{
    Coo(int n){
      n=n+1;
        System.out.println(n);//30
    }
}
class Doo extends Coo{

    Doo() {
        super(25);//调用父类的有参构造  这个就无用了？？
    }
}
class Aoo{
    Aoo(){
        System.out.println("超类的构造器");
    }
}
class Boo extends Aoo{
    Boo(){
        super();
        System.out.println("派生类的构造方法");
    }
}