Encapsulation

By default class members have package scope. So they are accessible from anywhere in this package.

There are three modifiers that change access rules for class members.

• public - member accessible from anywhere
• protected - member accessible from same package and from its child classes
• private - member accessible only for owner class

public class  Parent{
    public int field1 = 10;
    protected int field2 = 11;
    private int field3 = 12;
    
     public void method1(){
        System.out.println(field1);
        System.out.println(field2);
        System.out.println(field3);
    }
}

public class Child extends Parent {
    public void method1(){
        System.out.println(field1);
        System.out.println(field2);
        // error, field3 is private member in parent class
       System.out.println(field3);
    }

    public void method2(){
        Parent parent = new Parent();
        System.out.println(parent.field1);
        System.out.println(parent.field2);
        // error, field3 is private member in parent class
        System.out.println(parent.field3);
    }

public class Other{
    public void method1(){
        Parent parent = new Parent();
        System.out.println(parent.field1);
        // error if Parent and Other in different packages
        System.out.println(parent.field2);
        // error, field3 is private member in parent class
        System.out.println(parent.field3);
    }
}