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Thread: Variables

  1. #1
    toiletpaper is offline Member
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    Default Variables

    Hello again,

    Whats the difference between class variables, instance variables, local variables, global variables ?? Could u plz provide some examples as an illustration ?

    Thanks in advance,
    Regards,
    toiletpaper

  2. #2
    Norm's Avatar
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    Default Re: Variables

    If you don't understand my response, don't ignore it, ask a question.

  3. #3
    toiletpaper is offline Member
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    Default Re: Variables

    What about global variables ??

  4. #4
    jim829 is online now Senior Member
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    Default Re: Variables

    There is no such think as a global variable in Java. The closest thing would be public static class variables.
    But I don't consider them a real global variables. Besides, they aren't needed (imho). If someone thinks they
    really need them then they should probably re-architect their app.

    Regards,
    Jim
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  5. #5
    gimbal2 is offline Just a guy
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    Default Re: Variables

    Quote Originally Posted by jim829 View Post
    There is no such think as a global variable in Java. The closest thing would be public static class variables.
    But I don't consider them a real global variables. Besides, they aren't needed (imho). If someone thinks they
    really need them then they should probably re-architect their app.
    +1, although constants (public static final) are still a useful thing.
    "Syntactic sugar causes cancer of the semicolon." -- Alan Perlis

  6. #6
    toiletpaper is offline Member
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    Default Re: Variables

    PHP Code:
    public class Die
    {
    private final int MAX = 6;
    
    .
    .
    .
    
    }
    Is this considered as a static int ? Is it a class variable ?

  7. #7
    JosAH's Avatar
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    Default Re: Variables

    Quote Originally Posted by toiletpaper View Post
    PHP Code:
    public class Die
    {
    private final int MAX = 6;
    
    .
    .
    .
    
    }
    Is this considered as a static int ? Is it a class variable ?
    I don't see the 'static' keyword anywhere, so it isn't a static variable; it is a private variable (can't be 'seen' outside the class) and it is final, so it can't be changed anywhere in the object.

    kind regards,

    Jos
    cenosillicaphobia: the fear for an empty beer glass

  8. #8
    toiletpaper is offline Member
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    Default Re: Variables

    What if i declared it as final int MAX = 6; it still wouldn't be considered as a class variable correct ?

  9. #9
    SurfMan's Avatar
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    Default Re: Variables

    Quote Originally Posted by toiletpaper View Post
    What if i declared it as final int MAX = 6; it still wouldn't be considered as a class variable correct ?
    Yes, variables that are NOT static are NOT class variables, those are instance variables.

    Instance variables (non-static fields) are unique to each instance of a class. Class variables (static fields) are fields declared with the static modifier; there is exactly one copy of a class variable, regardless of how many times the class has been instantiated. Local variables store temporary state inside a method. Parameters are variables that provide extra information to a method; both local variables and parameters are always classified as "variables" (not "fields").
    Source: Summary of Variables (The Java™ Tutorials > Learning the Java Language > Language Basics)

    Edit: answered the question.
    Last edited by SurfMan; 05-08-2014 at 11:41 AM.
    "It's not fixed until you stop calling the problem weird and you understand what was wrong." - gimbal2™ © 2013

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