Explain to me what is a setter and getter

Question

What are setters and getters? Why do I need them? What is a good example of them in use in an effective way? What is the point of a setter and getter?

Update: Can I get some coding examples please?

Answer 1

A getter/setter is used to hide a private field from the publicity (you can avoid direct access to a field).

The getter allows you to check a provided value before you use it in your internal field. The setter allows you for instance to apply a different format or just to restrict write access (e.g. to derived classes).

A useful application of a getter can be some kind of lazy loading: The backing field (the private field that is hidden by the getter) is initialized to null. When you ask the getter to return the value, it will check for null and load the value with a more time consuming method. This will happen only the first call, later the getter will provide the already loaded value all the time.

Answer 2

A getter is a method that gets the value of a property. A setter is a method that sets the value of a property. There is some contention about their efficacy, but the points are generally:

• for completeness of encapsulation

• to maintain a consistent interface in case internal details change

More useful is when you need to add some logic around getting or setting, like validating a value before you write it.

Answer 3

Getters & setters separate interface (getter/setter functions) from implementation (how the data is actually stored).

Answer 4

Getters and Setters allow you to control how data members of an object can be accessed or changed.

In contrast, if you expose your data members directly to the user of the object, the user can change them at will, and the object wouldn't even know that they had been changed.

Don't want people to read a data member? Make the data member private, and don't write a getter that gives the value back. Don't want people to modify a data member? Make the data member private, and don't write a setter for it. Want to control the range of allowed values? Put that in the setter.

Answer 5

public accessors(getter and setter) make sometimes sense. (I'm annoyed that I have not only to document the member variable of a class but also the 2 mostly meaningless accessor methods. )

It usually doesn't help with encapsulation except in cases mentioned by Jason S.

An java example for some char loaded from a database but should be represented as a boolean value

char boolFromDb;

public boolean getBoolFromDb() {
    return boolFromDb == 'T';
}

public void setBoolFromDb(boolean newValue) {
    boolFromDb = newValue ? 'T' : 'F';
}