The actual cases and application scenarios of the UNDERSCORE framework in the Java library

The UNDERSCORE framework is a tool library to provide functional programming support for Java developers.Based on the idea of functional programming, it provides a series of convenient and concise functions, as well as the operation and processing methods of common data types such as collection, array, string. In the Java library, the Underscore framework can be applied to many practical cases and scenes.Below we will introduce several common application scenarios and provide corresponding Java code examples. ### Collection of data conversion and processing The UNDERSCORE framework provides many processing methods for set data.Through these methods, we can easily perform operations such as screening, mapping, filtering, etc., so as to quickly complete the conversion and processing of collection data. For example, suppose we have a list of student objects, and each student object contains two attributes: name and age.Now we want to find students older than or equal to 18 years old and save their names into a new list.Using the Underscore framework, we can implement it like this: List<Student> students = Arrays.asList( new Student("Alice", 17), new Student("Bob", 20), new Student("Charlie", 19) ); List<String> adultStudents = _.chain(students) .filter(student -> student.getAge() >= 18) .map(Student::getName) .value(); System.out.println (adultStudents); // Output: [Bob, Charlie] In the above code, we use the `chain` method of the UNDERSCORE framework to operate the collection data for chain.First use the `Filter` method to screen students who are more than or equal to 18 years old, and then use the` Map` method to convert the student object to name string, and finally obtain the converted result through the `value` method. ### function combination and call The combination and call of the function are one of the important concepts of functional programming, and the UNDERSCORE framework provides a set of simple methods to implement the combination and call of the function. For example, we have two functions `addone` and` doublenumber`, which will double a number 1 and one will double.Now we want to double the number after 1.Using the Underscore framework, we can implement it like this: Function<Integer, Integer> addOne = num -> num + 1; Function<Integer, Integer> doubleNumber = num -> num * 2; Function<Integer, Integer> composedFunction = _.combine(addOne, doubleNumber); int result = composedFunction.apply(3); System.out.println (result); // Output: 8 In the above code, we use the UNDERSCORE framework's `Combine` method to combine the two functions to get a new function` composedFunction`.Then, we can call this combination function through the `apply` method, and pass the parameter 3 to get the final result. ### string processing and operation The UNDERSCORE framework also provides some processing methods for string, so that we can easily perform operations, cutting, and replacing the string stitching, division, and replacement of the string. For example, we have a string containing file paths, and now we want to get file names (excluding paths and extensions).Using the Underscore framework, we can implement it like this: String filePath = "/path/to/file.txt"; String fileName = _.chain(filePath) .split("/") .last() .split(".") .head() .value(); System.out.println (filename); // Output: file In the above code, we use the `chain` method of the UNDERSCORE framework to operate the string.First use the `split` method to divide the path into a string array according to the`/`, and then use the` Last` method to obtain the last element in the array. FinallyUse the `head` method to obtain the first element in the array. The above is just a brief introduction to some practical cases and scenes of the UNDERSCORE framework in the Java class library.In fact, the UNDERSCORE framework also provides more rich functions and methods, which can help developers more conveniently perform functional programming and data processing.In actual development, we can choose the appropriate UNDERSCORE framework method according to specific needs.