The role of Java function generics in polymorphism

The role of Java function generics in polymorphism: Provide polymorphism, allowing functions to operate on different types of data. Improved code maintainability, flexibility, and reduced duplication. Syntax: void myFunction(T argument), where T is a generic type parameter. Actual case: Generic function to calculate the size of a data list int size(List list) { return list.size(); }. Advantages: Code reusability, flexibility, type safety.

The role of Java function generics in polymorphism

Function generics in Java provide polymorphism, allowing Create general-purpose functions that operate on different types of data. Polymorphism makes code more maintainable, more flexible, and helps reduce code duplication.

Syntax

A function declaration containing function generics looks like this:

<T> void myFunction(T argument) {
  // 操作 Argument
}

where T is the generic type parameter , will be replaced with the actual type at compile time.

Actual case

Consider a function that calculates the size of a data list:

int size(List<?> list) {
  return list.size();
}

The function takes a wildcard type parameter? , indicating that the function can receive any type of list. However, we cannot directly call the size() function:

List<Integer> integers = new ArrayList<>();
int result = size(integers); // 编译错误：无法将 List<Integer> 赋值给 List<?>

To solve this problem, we can use a generic function:

<T> int size(List<T> list) {
  return list.size();
}

Now, we can safely call size() Function:

int result = size(integers); // 成功编译

Advantages

Using function generics to provide polymorphism has the following advantages:

• Code reusability: Generic functions can be used to operate on different types of data, eliminating the need for repeated code.
• Flexibility: Functions can dynamically adapt to different types as needed, making the code more flexible.
• Type safety: The compiler checks type compatibility at compile time, providing additional type safety.

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