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Engineering LibreTexts

14.4: Overloading

  • Page ID
    15245
  • You might have noticed that circleArea and calculateArea perform similar functions. They both find the area of a circle, but they take different parameters. For calculateArea, we have to provide the radius; for circleArea we provide two points.

    If two methods do the same thing, it is natural to give them the same name. Having more than one method with the same name is called overloading, and it is legal in Java as long as each version takes different parameters. So we could rename circleArea to calculateArea:

    public static double calculateArea (double xc, double yc, double xp, double yp) {
        return calculateArea(distance(xc, yc, xp, yp));
    }
    

    Note that this new calculateArea method is not recursive. When you invoke an overloaded method, Java knows which version you want by looking at the arguments that you provide. If you write:

    double x = calculateArea(3.0);

    Java looks for a method named calculateArea that takes one double as an argument, and so it uses the first version, which interprets the argument as a radius. If you write:

    double y = calculateArea(1.0, 2.0, 4.0, 6.0);
    

    Java uses the second version of calculateArea, which interprets the arguments as two points. In this example, the second version actually invokes the first version.

    Many Java methods are overloaded, meaning that there are different versions that accept different numbers or types of parameters. For example, there are versions of print and println that accept a single parameter of any data type. In the Math class, there is a version of abs that works on doubles, and there is also a version for ints.

    Although overloading is a useful feature, it should be used with caution. You might get yourself nicely confused if you are trying to debug one version of a method while accidentally invoking a different one.