Any practical difference in the use of Java's static method main?

Question

If I have the following Java class :

public class MyClass
{
  ...

  public static void main(String[] args) 
  {
   ...
  }
}

Is there any practical difference if I call it in the 2 different ways below ?

[1] new Stock_Image_Scanner().main(null);
[2] Stock_Image_Scanner.main(null);

Depends on what the constructor does... – Oliver Charlesworth Feb 23 '14 at 22:23 — Oliver Charlesworth, Feb 23 '14 at 22:23
`MyClass.main(null)` is the proper way (static access) – Feb 23 '14 at 22:25 — , Feb 23 '14 at 22:25

score 6 · Answer 1 · answered Feb 23 '14 at 22:23

6

In the first one the constructor gets executed. In the second one it does not.

answered Feb 23 '14 at 22:23

kg_sYy

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ANd in the first example an object is allocated (and gets available for garbage collection immediately if the constructor doesn'T save a reference to the object in any static property). – Johannes H. Feb 23 '14 at 22:24

score 4 · Answer 2 · edited May 23 '17 at 12:10

4

main is a static function, and should not be called via an instance. It should only be called via the class name:

Stock_Image_Scanner.main(null);

In addition, null should really be changed to new String[]{}. And as stated @kg_sYy, the new way (via the instance) executes the classes constructor, which is generally unexpected and not recommended.

More info:

edited May 23 '17 at 12:10

Community

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answered Feb 23 '14 at 22:25

aliteralmind

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2

+1 calling a static method via an instance is just confusing. – Peter Lawrey Feb 23 '14 at 22:30

score 3 · Answer 3 · edited Feb 24 '14 at 01:07

3

Just to say the same thing in yet another way:

new Stock_Image_Scanner().main(null);

Does the same thing as:

new Stock_Image_Scanner();
Stock_Image_Scanner.main(null);

edited Feb 24 '14 at 01:07

Benjamin Gruenbaum

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answered Feb 23 '14 at 22:26

Johannes H.

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Any practical difference in the use of Java's static method main?

3 Answers3

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