Compare and contrast between Java closures and anonymous functions

Both closures and anonymous functions in Java are anonymous inner classes, but closures can save state beyond their creation environment, while anonymous functions only perform one operation and are limited to their creation environment.

Closures and anonymous functions in Java

Overview

Closures and anonymous functions in Java are both anonymous inner classes that allow access to variables in the environment in which they are created, but there are subtle differences between the two.

Closure

• A closure is an anonymous inner class with private variables and saveable state
• A closure can contain its creation environment variables in the object and provide persistent access to them
• Closures are returned or passed as properties or methods of the object, thereby extending the life of the environment in which it was created

Anonymous function

• Anonymous function is an anonymous inner class that performs only one operation
• Anonymous function is essentially a "one-time" function because it has no state
• Anonymous functions are often used as Lambda expressions to write code more concisely

Comparison tables

Features	Closure	Anonymous function
State	Save the state and can modify it	No state
Scope	Beyond its creation environment, as long as the reference exists	Limited to its creation environment
Instantiation	Use new operator	Through Lambda expression
Purpose	Lazy initialization, state Management	Handling one-time tasks, worrying about simplification

Practical case

Closure example

// 用于延迟初始化的闭包
public static Supplier<String> createLazySupplier() {
    String name = "Alice";
    return () -> name;
}

Anonymous function example

// 用于排序的匿名函数
Arrays.sort(array, (a, b) -> Integer.compare(a, b));

Conclusion

Both closures and anonymous functions are useful tools in Java , they allow the creation of flexible and efficient code. Choosing which one to use depends on the features required for a specific use case.

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