Initialize() vs. Constructor()

Question about the task

Create a Dog class

Java Syntax, Level 5, Lesson 7

Under discussion

Anyone, why would we use initialize() instead of construcor().

Create a Dog class with three initializers:
- Name
- Name, height
- Name, height, color

Requirements:

The program must not read data from the keyboard.
The Dog class must have a String variable name.
The Dog class must have an int variable height.
The Dog class must have a String variable color.
The class must have an initialize method that takes a name as an argument and initializes the corresponding instance variable.
The class must have an initialize method that takes a name and height as arguments, and initializes the corresponding instance variables.
The class must have an initialize method that takes a name, height, and color as arguments, and initializes the corresponding instance variables.

package com.codegym.task.task05.task0511; /* Create a Dog class */ public class Dog { //write your code here String name; int height; String color; //Dog dog1 = new Dog(); public void initialize(String name) { this.name = name; this.height = 12; this.color = "Black"; } public void initialize(String name, int height) { this.name = name; this.height = height; this.color = "Black"; } public static void main(String[] args) { } }

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Guadalupe Gagnon

Level 37 , Tampa, United States

23 September 2020, 14:40

The initialize() method was the generally accepted standard way to properly set up an object before constructors were introduced/invented in object orientated programming. This is well before Java. This created a number of problems, for example when a programmer would create an object and neglect to to call the initialize method before actually using the object; or when a class creator would create methods that initialized the created objects of that class but didn't call them initialize(). Imagine, if you will, if you had to do this for to properly set up, for example, user input from keyboard:

BufferedReader reader = new BufferedReader();
InputStreamReader inputStream = new InputputStream();
inputStream.initialize(System.in);
reader.initialize(inputStream);

or an even worse example, if the class creator didn't use a standard initialize method:

BufferedReader reader = new BufferedReader();
InputStreamReader inputStream = new InputputStream();

// if they had different method names that "initialized"
inputStream.ValidateObject(System.in);
reader.setUpToUse(inputStream);

/*OR*/
Scanner scan = new Scanner();
scan.validate(System.in)

In the second code example, imagine if all the Java classes had different names for what was essentially an "initialize" method (Java has somewhere around 4500 classes in the standard library). This was actually happening before constructors were invented.

Guadalupe Gagnon

Level 37 , Tampa, United States

23 September 2020, 14:40

The invention of constructors solved these problems, and others, by forcing a standard way of initializing objects instead of leaving it up to the discretion of the programmers using a language. Now a constructor is called on every new object creation regardless of whether or not one is specified, but typically one is specified and handles the job the initialize() method used to do. Now with all that being said, you most likely won't ever use initialize() in your career unless you work on some old non-java legacy code, or for very specialized code/specifications. It is important to know about the initialize() method in that you can appreciate the use of constructors.

Vladan

Level 17 , Belgrade, Serbia

23 September 2020, 13:41

Well, you should regard these tasks as some kind of introduction to constructors

hidden #10668264

Level 7

22 September 2020, 17:21

I created the third initialize method after I posted the question. Dziękuję.

Misiu

Level 41 , Gdansk, Poland

22 September 2020, 17:29

Nice :)

Misiu

Level 41 , Gdansk, Poland

22 September 2020, 14:53

"The class must have an initialize method" Such is a goal of the task. Leads us toward constructors. Constructors will be in next lessons and tasks. Where is your third initialize() method?