Java Constructors- Assigning value to variable

Question

Is there a difference between assigning values to variables outside of any method, and assigning these values within a constructor?

Looking at Oracle's Java tutorial, they have:

public class Bicycle {

   int cadence = 0;
   int speed = 0;
   int gear = 1;

   void changeCadence(int newValue) {
      cadence = newValue;
   }

is this any different from saying/why didn't they just say:

Bicycle(){
    int cadence = 0;
 } 

Answer 1

If you declare the variable in your constructor, it will be local to the constructor and not visible anywhere else in your class.

Answer 2

If you declare a variable inside a constructor, this variable can only be accessed inside this constructor. But, you can create a variable on your class, and access it on your constructor or method.