Replace Magic Stuff with Constants

Code Smells

• Code uses numbers that have a certain meaning to it
• Code uses strings that have a certain meaning to it

Make it harder to understand the program and refactor the code

Technique

• Extract the magic stuff by using your IDE feature
  • Makes its name self-evident

Practice

• Open Utils in organizing.data package
• Extract magic stuff

public class Utils {
    public static void validatePassword(String password) {
        if (password.length() < 12) {
            throw new IllegalArgumentException("minimum password length is not respected");
        }
    }

    public static double calculatePotentialEnergy(double mass, double height) {
        return mass * height * 9.81;
    }
}

Shortcuts

Extract Constant :

Benefits

• Symbolic constant can serve as live documentation of the meaning of its value
• Reduce duplicate use of a number in the code

Drawbacks

• N/A

Encapsulate fields

Code Smells

• From public to private fields
• Ideally expose just behaviors (methods / functions)

One of the pillars of object-oriented programming is Encapsulation : the ability to conceal object data.

Technique

• Make the field private and create access methods for it

Practice

• Open Wizard in organizing.data package
• Encapsulate fields

public class Wizard {
    public String weapon;
    public String magicStick;
    public String name;
    public int life;

    public Wizard(String name) {
        this.name = name;
    }
}

Shortcuts

• Right Click in the file
• Refactor | Encapsulate Fields

• Then configure the encapsulation
• More info here

Benefits

• Preserve the state of your object
  • No side effect from the outside
• Much easier for you to maintain and develop this component

Drawbacks

• N/A