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Thread: Having Trouble Linking a method from another class!

  1. #1
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    Exclamation Having Trouble Linking a method from another class!

    Please read all of this before commenting! Thank you!

    Im fairly new to Java, i use the BlueJ software to develop my programs.

    I am creating a program which holds two data structures; Array List and Binary Tree. I have created a person class which is used to declare variables containing people, this class also contains a method which prompts the user to input 3 characters of a memorable word. These people are created within the array list and binary tree. This actually works in practice, within the program, but i get an error, and i need the program to contain no errors.

    In my binary tree class, i want to call this method.

    I have attached 4 images to this post, an overview of the classes used, a look at highlighted code which is an attempt at calling a method from the person class, and the method contained within the person class itself. Note that the person class is just called "Person". The 4th image is the error being displayed.

    And moderators, if this post is in the wrong place can you please move it as opposed to deleting it, i spent time typing this up and i am going to bed.

    overview.jpgnonworkingcode.PNGpublicvoidmethod.PNGerror.jpg


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Having Trouble Linking a method from another class!

    To call a method in a class, you need a reference to that class(ignoring static methods).

    Sometimes you need to pass that reference from one class where it was assigned a value to the class that needs it to make the call.

    Post any code here that shows the problem, Be sure to wrap the code in code tags.
    Also post the full text of the error message.
    If you don't understand my answer, don't ignore it, ask a question.

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    Default Re: Having Trouble Linking a method from another class!

    (New to Java and unsure of your error, but going to take a shot at it)

    Norm spoke of static methods above. After learning about static methods previously, I recommend making the inputMemorableWord method a static method, if you do not create an instance of the class that holds the inputMemorableWord method.

    Instead of this:
    public void inputMemorableWord() {
       //your code here
    }

    Suggesting this:
    public static void inputMemorableWord() {
       //your code here
    }

    To the more experienced Java programmers, please let me know if I am wrong to correct errors before it becomes a bad habit.

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    Administrator copeg's Avatar
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    Default Re: Having Trouble Linking a method from another class!

    Quote Originally Posted by Votek View Post
    ...I recommend making the inputMemorableWord method a static method...

    To the more experienced Java programmers, please let me know if I am wrong to correct errors before it becomes a bad habit.
    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.

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