Analysis of the technical principles of Google Collections in the Java collection library framework

Analysis of the technical principles of Google Collections in the Java collection library framework Google Collections is a set of enhanced tool packs based on Google.It provides a series of powerful and superiority collection tools that can provide richer and more convenient collection operation methods for Java developers.This article will analyze the technical principles of Google Collections and demonstrate its usage through the Java code example. 1. motivation Before analyzing the technical principles of Google Collections, let's take a look at its motivation.Although the Java collection library provides a wealth of collection classes, there are still some shortcomings in some scenarios.For example, many of the operations in the Java set library need to be achieved through the iterator, which is a tedious and easy -to -error mode.In addition, common collection operations, such as filtering, conversion, sorting, etc., have not received good support.Google Collections was born to solve these problems. 2. Technical principles Google Collections's technical principles mainly include the following aspects: 2.1 Unchanged collection Google Collections introduces the concept of uncharacteria.Unable to be modified after the creation, so that the risk of concurrent modification is eliminated.They are safe threads and can be freely shared and reused.Unable to change the internal data structure to achieve efficient memory utilization and fast operating performance. Here are a sample code that uses inseparable collection: ImmutableSet<String> set = ImmutableSet.of("a", "b", "c"); 2.2 New collection type In addition to the uncharacteristic set, Google Collections also introduced some new collection types, such as Multiset and Multimap.Multiset is an disorderly, repeated set, which can count the number of times the element appears in the collection.Multimap is a one -to -many mapping relationship, which can associate multiple values on one key. The following is a sample code using Multiset and Multimap: Multiset<String> multiset = HashMultiset.create(); multiset.add("a"); multiset.add("b"); multiset.add("a"); Multimap<String, String> multimap = HashMultimap.create(); multimap.put("key1", "value1"); multimap.put("key1", "value2"); multimap.put("key2", "value3"); 2.3 Functional Programming Support To support functional programming styles, Google Collections introduced some functional interfaces and tool classes.For example, the Function interface can map one object to another, and the Predicate interface can be used to set the filtering judgment of the element. The following is an example code that uses functional programming: List<Integer> numbers = Lists.newArrayList(1, 2, 3, 4, 5); List<Integer> evenNumbers = Lists.newArrayList(Collections2.filter(numbers, num -> num % 2 == 0)); 3. Summary Through the above technical principles, we can see that Google Collections provides more powerful and convenient collection tool classes on the basis of the Java collection library.It uses technical means such as uncharacteria, new collection types and functional programming support, so that we can better handle the collection operation.I believe that with the application of Google Collections, Java developers can get a more efficient and convenient collection processing experience. It is hoped that this article will help Google Collection ’s technical principles and can provide some guidance for readers' learning and use.