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Android Build an Interactive Story App (Retired) The Model-View-Controller Pattern Adding a Custom Constructor

Ernest Lin
Ernest Lin
2,691 Points

How do you make a constructor?

How do you make a constructor? I still don't get this...

2 Answers

Kristian Gausel
Kristian Gausel
14,649 Points

The constructor of a class named ClassExample will look like this:

public ClassExample (){

}

Where you can have arguments inside the parenthesis as with any other method.

Daniel Maia
Daniel Maia
6,228 Points

Kristian is correct, a simple empty default constructor is created as per above.

However, when you create a class, you can think of a car, as an example. So, the questions you should ask yourself are:

  1. Make of the car?
  2. Model of the car?
  3. Number of doors?
  4. Color of the car? etc.

Now this may look something like this:

public class BMW {

  public String mMake;
  public String mModel;
  public int mNumberOfDoors;
  public String mColor;

  // The Contructor will be used when the class is initiated
  public Car(String make, String Model, int doors, String color) {
     mMake = make;
     mModel = model;
     mNumberOfDoors = doors;
     mColor = color;
  }

// Below you would of the rest the code such as setters and getters etc. 

......
}

As you can see above the constructor would be the first thing created when you create the Car object. Now if I was to create this class it may look something like this:

Car myNewCar = new Car("BMW", "Z4", 3, "Silver");

Now the myNewCar object will contain the properties of BMW, Z4, 3 and SIlver to which can then be used later on for other things.

I hope this is clear, if you have any questions let me know.