Overview of the "function" framework in the Java class library
Overview of the functional programming framework in the Java class library
Overview:
Functional programming is a programming paradigm, and its main idea is to consider the calculation process as a conversion between functions.The concept of functional programming is introduced in the Java library, so that developers can more conveniently use functional programming styles to write code.The functional programming framework provides a set of functional functional interfaces and tool classes, making functional programming more concise, easy to read and easy to maintain.
Advantages of the functional programming framework in the Java class library:
1. Functional programming framework provides rich functional interfaces, such as Function, Predicate, SUPPLIER, etc., which can effectively support various operations of functional programming, such as mapping, screening, filtering, aggregation, etc.
2. The functional programming framework adopts simple LAMBDA expression syntax, making the code read higher and can reduce the writing of redundant code.The introduction of this grammar can make developers more focused on the essence of the problem, rather than pay too much attention to how to achieve it.
3. Functional programming framework provides support for thread security function interfaces and parallel processing, which can help developers better use the multi -core processor and improve the performance of the program.
Core concept of functional programming framework:
1. Functional Interface: It is the basis of functional programming in the Java class library. It is an interface with only one abstract method.By using @functionalInterface annotations, you can clearly declare that an interface is a functional interface.Function interfaces can be instantiated with lambda expression or method reference.
Below is an example:
@FunctionalInterface
interface MyFunctionalInterface {
void myMethod();
}
public class Main {
public static void main(String[] args) {
MyFunctionalInterface functionalInterface = () -> System.out.println("Hello, World!");
functionalInterface.myMethod();
}
}
2. Lambda expression: Lambda expression is an anonymous function that can be passed to the function interface without declaration.Its grammar form is: (parameter list) -> expression.
Below is an example:
public class Main {
public static void main(String[] args) {
Runnable runnable = () -> System.out.println("Hello, World!");
Thread thread = new Thread(runnable);
thread.start();
}
}
3. Method reference: Method reference is a simplified form of Lambda expression. It can directly reference the existing methods to replace Lambda expression.
There are several forms of the following methods:
-Rodia method quotes: className :: StaticMethodName
-The method reference: Instance :: InstanceMethodName
-The constructive method quotes: className :: NEW
Below is an example:
import java.util.function.Supplier;
public class Main {
public static String createString(Supplier<String> supplier) {
return supplier.get();
}
public static String getInstanceMethod() {
return "Hello, World!";
}
public static void main(String[] args) {
String result = createString(Main::getInstanceMethod);
System.out.println(result);
}
}
Summarize:
The functional programming framework in the Java class library provides rich functional interfaces and tool classes, making functional programming more concise, easy to read and maintain.By using LAMBDA expressions and methods, developers can more conveniently use functional programming styles to write code, and can better use multi -core processors to improve program performance.
