Is encapsulation recommended for private static inner classes?

Question

If you have a private static nested class in Java, is it still recommended to use getters and setters rather than direct field access?

An example. Direct field access:

public class Application {
    private List<MyInnerClass> myInnerClassList;

    // ...

    public void foo() {
        MyInnerClass inner = new MyInnerClass();
        inner.bar = 50;
        myInnerClassList.add(inner);
    }

    private static class MyInnerClass {
        private int bar;
    }
}

vs encapsulation:

public class Application {
    private List<MyInnerClass> myInnerClassList;

    // ...

    public void foo() {
        MyInnerClass inner = new MyInnerClass();
        inner.setBar(50);
        myInnerClassList.add(inner);
    }

    private static class MyInnerClass {
        private int bar;

        public int getBar() {
            return bar;
        }

        public void setBar(int bar) {
            this.bar = bar;
        }
    }
}

Answer 1

Depends but generally I think it is ok. One of the main reasons to use getters and setters is to hide implementation details from the user of the class so you can easily change implementation without affecting the user.

In the case of a private inner class, this is not an issue because you are both the writer and the user of the class, and no one from outside can use it.

If you just use to hold some data together, not having getters and setters will make the code shorter and more readable.

But, if the inner class is bigger and more complicated (which is usually not the case), then you should consider using getters/setters. This will enable you, e.g., to add bounds checking to bar in your code.