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This article mainly introduces "What is Collection Interface". In daily operation, I believe many people have doubts about what Collection Interface is. Xiaobian consulted all kinds of materials and sorted out simple and easy operation methods. I hope to help you answer the doubts about "What is Collection Interface"! Next, please follow the small series to learn together!

Introduction to the Cluster Framework

From JDK1.2, Java introduced the class set development framework, the so-called class set refers to a set of dynamic object array implementation scheme, in actual development, no development can leave the array, but the traditional array implementation is very cumbersome, and length is its fatal flaw, it is precisely because of the length problem, so the traditional array is impossible to use in a wide range, but development can not be separated from the array, Therefore, at first, we can only rely on some data structures to achieve dynamic array processing, and the two most important structures: linked list and tree. However, in the face of the implementation of these data structures, we have to face the following problems:

Data structure code implementation is difficult, for the general developer is unable to use;

For linked lists or binary trees, maintenance is cumbersome when updating;

For linked list or binary tree, it is necessary to ensure the performance of its operation as much as possible;

It is for this reason that Java has introduced class sets since JDK 1.2, mainly to complete the implementation of common data structures, and to provide a series of interfaces and implementation subclasses to help users reduce the development difficulties caused by data structures. However, the initial implementation of the class set is limited by Java's own technology, so the control of the data is not strict, all using the Object type for data reception, and after JDK1.5 due to the promotion of generic technology, so the class set itself has also been well improved, you can directly use generic to save the same type of data, and with the increasing amount of data, from JDK1.8 on the implementation algorithm of the class set has also been a good performance upgrade.

In the entire class set framework, the following core interfaces are provided: Collection, List, Set, Map, Iterator, Enumeration, Queue, ListIterator.

Collection collection interface

java.util.Collection is the largest parent interface for single-valued collection operations. All single-valued data processing operations are defined in this interface. The following core operation methods are defined in this interface:

No. Method Name Type Description 01public boolean add(E e) Save data to a collection 02public boolean addAll(Collection)

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