Encapsulate Field

Replace public fields (instance variables) with private fields and provide public accessors.

Original code:

 public class Person {
   public String name;
 }

Refactored:

 public class Person {
   private String name;
   
   public void setName(String newName) {
       name = newName;
   }
   
   public String getName() {
       return name;
   }
 }