What are the specialties of using generics in Java function overloading mechanism?

During Java function overloading, generic parameters will be erased, causing overloading of generic methods of the same original type to become invalid. The solution is to use wildcard types, such as and Object, to overload generic and non-generic methods for different primitive types.

The particularity of generics in Java function overloading mechanism

Java function overloading refers to the function overloading in the same class Define multiple methods with the same name but different parameter lists.

When generic type parameters are used in method signatures, the use of generic type parameters introduces some specialties in the function overloading mechanism:

Erasure of generic methods Type

At compile time, generic type parameters will be erased to the original type, for example:

public class Test {
    public <T> void print(T value) {
        System.out.println(value);
    }
}

In the compiled bytecode, print The signature of the method becomes:

public void print(Object value)

This will make overloading of generic methods of the same primitive type infeasible.

Solution

One solution is to use wildcard types, for example:

public <T> void print(T value) {
    System.out.println(value);
}

public void print(Object value) {
    System.out.println(value);
}

Now you can overload generics with different primitive types Type methods and non-generic methods.

Practical case

Consider the following example class:

public class Test {
    public <T> void add(List<T> list, T element) {
        list.add(element);
    }

    public void add(List<String> list, String element) {
        list.add(element);
    }
}

This class contains two add methods:

• A generic method that accepts generic lists and elements.
• A non-generic method specifically used to operate string lists.

Due to the use of wildcard types, these methods can be overloaded and compile and execute correctly.

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