Why getter and setter are better than public fields in Java

public modifier vs getter and setter method in Java

Providing getter and setter method for accessing any field of class in Java may look unnecessary and trivial at first place, simply because you can make field public and it’s accessible from everywhere in Java program. In fact many programmers do this in there early days but once you start thinking in terms of enterprise application or production code, you will start seeing how much trouble it can create in terms of maintenance. Since as per SDLC process, software spends more time in maintenance than development, it’s worth keeping ease of maintenance as one of goal in development. In reality using getter and setter method in Java is one of the Java coding best practice much like using @Override annotation while overriding method in Java. Main problem with making field public instead of getter and setter is that it violates Encapsulation by exposing internals of a class. Once you exposed internals of class you cannot change internal representation or make it better until making change in all client code. Since every code change comes with risk and cost of regression testing is high during maintenance, its not a good idea to make field public in Java.  In this Java tutorial we will see some more benefits getter and setter offers over public fields in Java.

What is getter and setter method in Java

For those who are new in Java and not very familiar with Java terminology, getter and setter method means method for accessing and modifying any property of a class in Java. For example in Counter class if we have a count variable than getCount() is getter method and setCount(int count) is a setter method in Java. Let’s see How much difference decision of making properties of class public makes over providinggetter and setter method in Java.

1) getter and setter method gives you centralized control on how a particular field is initialized and provided to client which makes validation and debugging much easier. you can simply put a breakpoints or print statement to see which thread are accessing and what values are going out.

On validation front, you can easily avoid an incorrect value for a particular field, i.e. if field is non nullable than you can throw NullPointerException. with public field your client code will break when it start using that field without knowing which part of your code is setting incorrect or null value.

2) By making fields private and providing getter and setter and following java bean naming convention you make your class usable with many open source library and framework e.g. display tag. which uses combination of reflection and Java bean naming convention to dynamically load and access fields.

3) with getter and setter you give an opportunity to Subclass to override these method and return what makes more sense in context of sub class.

Though I agree it make code more verbose and there are certainly cases where use of public field make sense. As we said by making a class field public violates Encapsulation but what if Class in question is private nested class or package private class, In that case they are well encapsulated and giving getter and setter can be avoided if you are not doing any validation and simply setting and getting value. Even in worst case if requirement changes comes and you need to perform sophisticated validation you can do this because all client code is within your reach.

So this was one of the best coding practices to follow on Java. Always try to make field private and final unless otherwise you have very good reason of not to do so. making fields private and providing getter and setter are standard Java coding standard and allows your code to be compatible with other framework which uses reflection.