Methods, variables, constructors, and structures that are declared private can only be accessed within the declaring class. This is with the exception of private top-level functions and properties that are visible to all members of the same file. Private variables within a class can be accessed from outside the class be declaring getter and setter methods that permit access. Defining setter and getter methods in Java is shown in the following code:

public class Person {
  Person(String fullName, int age) {
    this.fullName = fullName;
    this.age = age;
  }

  private String fullName;
  private int age;

  public String getFullName() {
    return fullName;
  }

  public int getAge() {
    return age;
  }
}

In Kotlin, setter and getter creation is as follows:

public class Person(private var fullName: String) {
  var name: String
  get() = fullName
  set(value)  {
    fullName = value
  }
}

Using the private access modifier is the main means of information hiding within programs. Information hiding is also known as encapsulation.