Java class IMPORTANT question


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Thread: Java class IMPORTANT question

  1. #1
    Join Date
    Oct 2005
    Location
    South Africa
    Posts
    1

    Exclamation Java class IMPORTANT question

    Hi I just wanted to know the following:

    When creating a class that inherits its objects and methods etc... from another class, you must create a constructer that uses super();

    eg:
    --------------------------------------------------------------------------
    import Aclassfile.*;

    public class stuff
    {
    public stuff(); //(<<<the constructer method)
    {
    super();
    }
    ...
    --------------------------------------------------------------------------

    and then u use normal methods that perform specific functions.But what happens when i use a normal class file, such as java.math.*; then must i still create a constructor method with the super(); code???

    eg: how do i create a class file that will ask the user do imput a double and then the program will find the sin, cos and tan of the inputted double, i have tried but am totally confused...please help!!!

  2. #2
    Join Date
    Nov 2004
    Location
    Norway
    Posts
    1,560
    The call to super() is not required, it will be invoked prior to the code in the
    descendant's constructor, povided that the superclass has a default (no parameters)
    constructor. If the superclass has no default constructor you have to implement
    your subclass so it calls one of the superclass' constructors as the first
    statement in your constructor(s).

    java.math is a package, java.lang.Math is a final class and cannot be
    extended, so in your case you can make yourself a plain (Object descendant) class
    that uses the java.Math class methods like static methods (double a=Math.sin(angle))
    eschew obfuscation

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