A Closer Look at
Methods and Classes
T
his chapter continues the discussion of methods and classes begun in the preceding
chapter. It examines several topics relating to methods, including overloading, parameter
passing, and recursion. The chapter then returns to the class, discussing access control,
the use of the keyword static, and one of Java's most important built-in classes: String.
Overloading Methods
In Java it is possible to define two or more methods within the same class that share the
same name, as long as their parameter declarations are different. When this is the case, the
methods are said to be overloaded, and the process is referred to as method overloading. Method
overloading is one of the ways that Java supports polymorphism. If you have never used
a language that allows the overloading of methods, then the concept may seem strange at
first. But as you will see, method overloading is one of Java's most exciting and useful features.
When an overloaded method is invoked, Java uses the type and/or number of
arguments as its guide to determine which version of the overloaded method to actually
call. Thus, overloaded methods must differ in the type and/or number of their parameters.
While overloaded methods may have different return types, the return type alone is
insufficient to distinguish two versions of a method. When Java encounters a call to an
overloaded method, it simply executes the version of the method whose parameters match
the arguments used in the call.
Here is a simple example that illustrates method overloading:
// Demonstrate method overloading.
class OverloadDemo {
void test() {
System.out.println("No parameters");
}
// Overload test for one integer parameter.
void test(int a) {
System.out.println("a: " + a);
}
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