Encapsulation in Java

Encapsulation in Java

Without encapsulation, outsiders can access and manipulate instance variables.

Encapsulation’s rule of thumb is to mark instance variables private and getters and setters as public.

class Dog{
    //instance variables as private
    private int size;
    
    //getters and setters as public 
    public int getSize(){
        return size;
    }
    public int setSize(int s){
        size= s;
    }
}

Through encapsulation, instance variables are protected via forcing code through setters. That way, the setter method can validate the parameter and decide if it’s durable. Maybe the method will reject it and do nothing, or maybe it’ll throw an Exception (like if it’s a null Social Security number for a credit card application), or maybe the method will round the parameter sent in to the nearest acceptable value.

How about setter methods that just set the value of instance variables. Doesn’t that just place unnecssasry overhead?

No, because The point to setters (and getters, too) is that you can change your mind later, without breaking anybody else’s code!