"Now it's high time that I tell you about constructors. This is really simple concept. Programmers have invented a shorthand way to create and initialize objects."

Without a constructor With a constructor 
MyFile file = new MyFile();
 file.initialize("c:\data\a.txt");
 String text = file.readText();
 
MyFile file = new MyFile("c:\data\a.txt");
 String text = file.readText();
 
MyFile file = new MyFile();
 file.initialize("c:\data\", "a.txt");
 String text = file.readText();
 
MyFile file = new MyFile("c:\data\", "a.txt");
 String text = file.readText();
 
MyFile file = new MyFile();
 file.initialize("c:\data\a.txt");

 MyFile file2 = new MyFile();
 file2.initialize( MyFile file, "a.txt");
 String text = file2.readText();
 
MyFile file = new MyFile("c:\data\a.txt");


 MyFile file2 = new MyFile(file, "a.txt");
 String text = file2.readText();
Java-университет

"I just finished learning about the initialize method…"

"Look harder. With constructors, the code is more convenient and compact."

"So it is. Here's a question. I know how to write an initialize method inside a class, but how do I write a constructor?"

"First, look at this example:"

Without a constructor With a constructor 
class MyFile
 {
   private String filename = null;

   public void initialize(String name)
   {
     this.filename = name;
   }

   public void initialize(String folder, String name)
   {
     this.filename = folder + name;
   }

   public void initialize(MyFile file, String name)
   {
     this.filename = file.getFolder() + name;
   }

 …
 }
 
class MyFile
 {
   private String filename = null;

   public MyFile(String name)
   {
     this.filename = name;
   }

   public MyFile(String folder, String name)
   {
     this.filename = folder + name;
   }

   public MyFile(MyFile file, String name)
   {
     this.filename = file.getFolder() + name;
   }

 …
 }

"It's easy to declare a constructor inside a class. A constructor is similar to the initialize method, with just two differences:

1. The name of a constructor is the same as the class name (instead of initialize).

2. A constructor has no type (no type is indicated)."

"OK, so it's like initialize, but with a few differences. I think I get it."