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Thread: Static Methods Preventing Usage of Instances?

  1. #1
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    Question Static Methods Preventing Usage of Instances?

    Hello,

    Copeg's post towards this thread:
    This fully depends upon how one wishes to use the method (unclear - at least to me - at this point) Declaring the method as static precludes one from using any sort of object oriented programming, thus the method cannot access instance fields of the object if it needs to.
    I created two short classes to sort of find out what this meant, but I feel I do not understand it well enough.

    Test class (main):
    package votek;
     
    public class Test {
     
    	public static void main(String[] args) {
    		SomeMethod();
    	}
     
    	public static void SomeMethod() {
    		Character character = new Character();
    		character.totalLevel = 50;
     
    		System.out.println(character.totalLevel);
    	}
     
    }

    Character class:
    package votek;
     
    public class Character {
    	private int level = 0;
     
    	public Character() {
    		level = 50;
    	}
     
    }

    OR

    Does it mean that making a static method in the class with private instances will prevent the method from using the private instances?
    Last edited by Votek; June 18th, 2014 at 12:55 AM.


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    Default Re: Static Methods Preventing Usage of Instances?

    Your example would be more representative of the use of OOP and related to Copeg's comment, if it were constructed like this:
    public class TestClass
    {
     
        public static void main(String[] args)
        {
            Character character = new Character();
            character.someMethod();
        }
     
    } // end class TestClass
    public class Character
    {
        private int level = 0;
     
        public Character()
        {
            level = 50;
        }
     
        public void someMethod()
        {
            System.out.println( "Level = " + level );
        }
     
    } // end class Character

  3. The Following User Says Thank You to GregBrannon For This Useful Post:

    Votek (June 17th, 2014)

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    Default Re: Static Methods Preventing Usage of Instances?

    And to extend off of Greg's code and the situation as I understood it in the linked post 1) suppose another class wishes to call 'someMethod', but you don't have a reference to a Character object (or don't know how to). 2) You choose to make someMethod static so you can just access it by calling Character.someMethod(). 3) A compile time error will result because 'level' is not static. 4) You can choose to make level static, but now its value will be the same for each object that is an instance of Character. 5) An alternative when given the situation in (1), is to somehow pass the reference of the object to the other class so that it can call the method.

  5. The Following User Says Thank You to copeg For This Useful Post:

    Votek (June 17th, 2014)

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    Default Re: Static Methods Preventing Usage of Instances?

    Tested the error and understand what you meant now.

    5) An alternative when given the situation in (1), is to somehow pass the reference of the object to the other class so that it can call the method.
    Is this the way that is supposed to be done?
    (Apologize if many questions follow.)

    TestClass class (main):
    package votek;
     
    public class TestClass {
     
    	public static void main(String[] args) {
    		Character knight = new Character(78);
    		Character mage = new Character(53);
    		Character ranger = new Character(29);
     
    		Team team = new Team();
     
    		team.sayCurrentLevel(knight);
     
    	}
     
    } //end class TestClass

    Character class:
    package votek;
     
    public class Character {
     
    	private int level = 0;
     
    	public Character(int level) {
    		this.level = level;
    	}
     
    	public void someMethod() {
    		System.out.println("Level = " + level);
    	}
     
    } //end Character class

    Team class:
    package votek;
     
    public class Team {
     
    	public void sayCurrentLevel(Character character) {
    		character.someMethod();
    	}
     
    } //end Team class

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    Default Re: Static Methods Preventing Usage of Instances?

    Tested the error and understand what you meant now.
    Great!

    Is this the way that is supposed to be done?
    Yes...if that's the behavior you want. Sorry for the vague answer, but answers to questions like this are very often context based (the context being what one wishes the program to do). While there are best practices there often is not really a 'supposed to' unless the code doesn't compile, throws Exceptions at runtime, or misbehaves.

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    Default Re: Static Methods Preventing Usage of Instances?

    Quote Originally Posted by copeg View Post
    Great!



    Yes...if that's the behavior you want. Sorry for the vague answer, but answers to questions like this are very often context based (the context being what one wishes the program to do). While there are best practices there often is not really a 'supposed to' unless the code doesn't compile, throws Exceptions at runtime, or misbehaves.
    Thank you for your time!

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