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Java Coding Problems - Second Edition

You're reading from  Java Coding Problems - Second Edition

Product type Book
Published in Mar 2024
Publisher Packt
ISBN-13 9781837633944
Pages 798 pages
Edition 2nd Edition
Languages
Author (1):
Anghel Leonard Anghel Leonard
Profile icon Anghel Leonard

Table of Contents (16) Chapters

Preface Text Blocks, Locales, Numbers, and Math Objects, Immutability, Switch Expressions, and Pattern Matching Working with Date and Time Records and Record Patterns Arrays, Collections, and Data Structures Java I/O: Context-Specific Deserialization Filters Foreign (Function) Memory API Sealed and Hidden Classes Functional Style Programming – Extending APIs Concurrency – Virtual Threads and Structured Concurrency Concurrency ‒ Virtual Threads and Structured Concurrency: Diving Deeper Garbage Collectors and Dynamic CDS Archives Socket API and Simple Web Server Other Books You May Enjoy
Index

195. Building a dynamic predicate from a custom map of conditions

Let’s consider the Car model and a List<Car> denoted as cars:

public class Car {
  private final String brand;
  private final String fuel;
  private final int horsepower;
  ...
}

Also, let’s assume that we receive a Map of conditions of type field : value, which could be used to build a dynamic Predicate. An example of such a Map is listed here:

Map<String, String> filtersMap = Map.of(
  "brand", "Chevrolet",
  "fuel", "diesel"
);

As you can see, we have a Map<String, String>, so we are interested in an equals() comparison. This is useful to start our development via the following Java enum (we follow the logic from Problem 194):

enum PredicateBuilder {
  EQUALS(String::equals);
  ...

Of course, we can add more operators, such as startsWith(), endsWith(), contains(), and so on. Next, based on the experience gained in...

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