Is this right? Implement and extend...

So, I'm learning Java (obviously), and I just learned how to 'implement' an interface and 'extend' a class. Now I want to try and recall the information by memory without using any reference material. So if someone experienced could respond with a thumbs up that'd be great ;) And if I got it right, then we'll just leave the information for others.

Implementing an interface...

Java Code:

//This interface will hold information for cell phones
//Like saying... you can't BE a cell phone unless you have this information, at the very least

public interface CellInfo {
     
     public void model();
     public void make();
     public void androidVer();

}

//Now I implement the interface for a class called Galaxy, which is a class about a specific phone

public class Galaxy implements CellInfo {

     public void model() {
          System.out.println("I'm a Galaxy S5.");
     }

     public void make() {
          System.out.println("I'm made by Samsung.");
     }

     public void androidVer() {
          System.out.println("I run Android 4.4 KitKat.");
     }

}

Extending a superclass with a subclass...

Java Code:

//This superclass will hold basic information that EVERY cell phone, regardless of make or model, must have

class Phone {

     int double screenSize = 5.3;
     int double weight = 10.2;
     int price = 300;

}

//Now I'll make a subclass that extends the Phone class, and this subclass of phones will be called iPhone

public class iPhone extends Phone {

     boolean hasAppleLogo = true;

     void adjustPrice() {
          if (hasAppleLogo) {
               //Slam on Apple...
               price += 500;
          }
      }

}