Question

I want to force future users of a class to access a private member also from future code written in that class only through an accessor method (even through junit or anything like that).

is there a way to do it in java? can someone show an example if possible?

Answer 1

You cannot force to do that, but you can create a method and document that enforcement in the javadoc.

private int myMember;

/**
* ATTENTION: use this method instead of setting the member directly.
*/
public void setMyMember(int value) {
  this.myMember = value;
}

Also, there is an alternative solution which might work. Use ThreadLocal, like this:

private final ThreadLocal<String> member = new ThreadLocal<String>();

public void setMember(final String value) {
  member.set(value);
}

The member field is final and cannot be changed. Therefore, clients will be forced to call the setter directly.