How to achieve type safety using Java function generics?

Generic functions improve the reusability and type safety of functions by using type parameters, allowing you to define functions that accept parameters of different types. You can specify bounds on type parameters to ensure that they subclass a specific type or implement a specific interface. The compiler can usually infer the type parameters, and you don't have to declare them explicitly if you specify the actual type of the parameter at the call site. Generic functions can be used to solve a variety of problems. For example, a generic function can find the largest element in a list, regardless of the type of the elements in the list, as long as they implement the Comparable interface.

Achieve type safety using Java function generics

Function generics are a powerful mechanism that allows you to define acceptance Functions with different types of parameters. This improves code reusability and type safety.

Syntax

Use angle brackets () to specify type parameters:

<T> T max(T a, T b) {
    // ...
}

Generic type boundaries

You can specify bounds on type parameters to ensure that they subclass a specific type or implement a specific interface:

<T extends Number> T sum(List<T> numbers) {
    // ...
}

Type inference

The compiler can usually infer type parameters. You don't have to explicitly declare the type parameter if you specify the actual type of the parameter at the call site: The largest element in:

Integer result = max(1, 2); // 编译器推断类型是 Integer

This generic function can accept any type that implements the Comparable interface, ensuring that it can compare elements and find the largest element.

You can use this function in the following code:

<T extends Comparable<T>> T findMax(List<T> list) {
    if (list.isEmpty()) {
        throw new IllegalArgumentException("List is empty");
    }

    T max = list.get(0);
    for (T element : list) {
        if (element.compareTo(max) > 0) {
            max = element;
        }
    }

    return max;
}

By using function generics, you ensure the versatility of your code and improve type safety. This prevents type errors and makes your code more robust.

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