[JAVA] Instance creation, constructor, field, etc.

Instance creation (at the time of new) ① Field initialization ② Call the constructor

• If there is no constructor, it will be created automatically.

Aaa o = new Bbb(100); When creating such an instance, jump to the constructor of Bbb class

System.out.println(o.a); In case of field, jump to the field of Aaa class which is type

o.sample() When the method is called, it jumps to the method of Bbb which is an object.

• Field → type Method → Let's remember it as an object