Does Java Method Overloading Consider Runtime Parameter Types for Method Selection?

Method Overloading and Parameter Type Determination

In Java, method overloading allows the definition of multiple methods with the same name but different signatures. When a method is called, the specific implementation to be invoked is determined at compile time based on the declared parameter types of the method.

However, it is important to note that this determination is made based solely on the declared types, not the actual runtime types of the arguments passed to the method. This behavior is in contrast to certain programming languages, where the actual runtime types are considered during method selection.

To illustrate this concept, consider the following code:

In this example, even though i is an Integer object, the call to callee.foo(i) will invoke the foo(Object o) method because the declared parameter type of that method is Object. Similarly, the calls to callee.foo(s) and callee.foo(o) will invoke the foo(String s) and foo(Object o) methods respectively.

Can Method Selection Consider Actual Parameter Types?

The Java language specification explicitly states that the method selection process considers only the compile-time types of the arguments, not their actual runtime types. Therefore, it is not possible to modify the code given in the question to achieve the desired behavior where the method is invoked based on the actual runtime type of the parameter.

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