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This article mainly explains "what are the knowledge points of Groovy and Scala in java". The content of the explanation is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn what are the knowledge points of Groovy and Scala in java.

Blend in

The concept of blending originated in the Flavors language (see Resources). The concept was inspired by an ice cream shop near the office where the language was developed. This ice cream shop offers pure flavor ice cream, as well as any other "mixture" that customers want (candy crumbs, sugar crumbs, nuts, etc.).

Some early object-oriented languages jointly defined the properties and methods of a class in a single block of code, and all class definitions were complete. In other languages, developers can define properties in one place, but defer the definition of methods and "mix" them into classes when appropriate. As object-oriented languages evolve, so do the details of how they blend in with modern languages.

In Ruby, Groovy, and similar languages, blending can extend existing class hierarchies as an intersection between interfaces and parent classes. Like interfaces, blending can act as a type of instanceof check, while also following the same extension rules. You can apply an unlimited number of mixes to a class. Unlike the interface, mixing not only specifies the method signature, but also implements the signature behavior.

In the first language that includes blending, blending contains only methods, not states, such as member variables. Many languages today (including Groovy) include stateful blending. The characteristics of Scala also operate in a stateful manner.

Blending of Groovy

Groovy mixes through the metaClass.mixin () method or the @ Mixin annotation. The @ Mixin annotation in turn uses Groovy Abstract Syntax Tree (AST) transformations to support the required metaprogramming pipeline. The example in listing 1 uses metaClass.mixin () to enable the File class to create a ZIP zip file:

Listing 1. Mix the zip () method into the File class

Class Zipper {def zip (dest) {new ZipOutputStream (new FileOutputStream (dest)). WithStream {ZipOutputStream zos-> eachFileRecurse {f-> if (! f.isDirectory ()) {zos.putNextEntry (new ZipEntry (f.getPath ()) new FileInputStream (f). WithStream {s-> zos

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