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Thread: Java cirkel

  1. #1
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    Default Java cirkel

    Create a class called Cirkel. The class shall have a constructor, which takes a parameter (radien). The radius shall be an instance variable. There shall also be to instance methods, one which returns the area and one which returns the circumference. There shall also be a class method for calculating the area of the circle (radius as parameter). After that create a testclass where a circle is created and the circumference is returned and written out. After that shall the area be returned and be written out with help of what is in the class, without creating an object (though invoking the class method).

    Hi! I have a problem with this assignment above. Anyone who can help?

    package cirkel;
     
    public class Cirkel {
          private double radien;
     
          public Cirkel(double r) {
            radien = r;
        }
          public double Diametern() {
            return 2*radien;
        }
          public double Omkretsen() {
            return Math.PI*radien*2;
        }
          public double Arean() {
            return Math.PI*radien*radien;
        }
    }

    package cirkel;
     
    public class circle {
        public static void main(String[] args){
            Cirkel CirkelObject = new Cirkel(4);
            CirkelObject.radien();
     
        }
    }

    This is how far i have reached.

    Thanks for help in advance


  2. #2
    Administrator copeg's Avatar
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    Default Re: Java cirkel

    No one will just post an answer for you..so providing as much information about where you are stuck, any errors you receive, and any behavior that is different than you want will help you as much as it will everyone else.

  3. #3
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    Default Re: Java cirkel

    Quote Originally Posted by copeg View Post
    No one will just post an answer for you..so providing as much information about where you are stuck, any errors you receive, and any behavior that is different than you want will help you as much as it will everyone else.
    Good to know since I am totally new in this...

    Then I would like to add that my biggest problem is to find connection between the classes and
    PHP Code:
    CirkelObject.radien(); 
    does not seem to work. Is "radien" wrong?


    Create a class called Cirkel. The class shall have a constructor, which takes a parameter (radien). The radius shall be an instance variable. There shall also be to instance methods, one which returns the area and one which returns the circumference. There shall also be a class method for calculating the area of the circle (radius as parameter). After that create a testclass where a circle is created and the circumference is returned and written out. After that shall the area be returned and be written out with help of what is in the class, without creating an object (though invoking the class method).

    Hi! I have a problem with this assignment above. Anyone who can help?

    package cirkel;
     
    public class Cirkel {
          private double radien;
     
          public Cirkel(double r) {
            radien = r;
        }
          public double Diametern() {
            return 2*radien;
        }
          public double Omkretsen() {
            return Math.PI*radien*2;
        }
          public double Arean() {
            return Math.PI*radien*radien;
        }
    }

    package cirkel;
     
    public class circle {
        public static void main(String[] args){
            Cirkel CirkelObject = new Cirkel(4);
            CirkelObject.radien();
     
        }
    }

  4. #4
    Administrator copeg's Avatar
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    Default Re: Java cirkel

    See the following for a description of Instance versus Class methods, which seems to be the issue here: Understanding Instance and Class Members (The Java™ Tutorials > Learning the Java Language > Classes and Objects)