构造函数重载和this调用构造函数

class test
{
public static void main(String[] args)
{
Dog dog=new Dog();
dog.printAgeCount();
}
}

class Dog
{
int age=0;
String name="alex";

Dog(int age){
this.age=age;
System.out.println("age="+age);
}
Dog(String name){
System.out.println("name="+name);
this.name=name;
}
Dog(String name,int age){
this(age);
this.name=name;
System.out.println("String & int age");
}
Dog(){
this("hello",20);
System.out.println("default constructor (no args)");
}
void printAgeCount(){
System.out.println("age="+age+"name="+name);
}
}