The class set framework in Java

1. What is a class set framework

1. is a set of classes and interfaces

2. Located in the Java.util package

3. Primarily for users to store and manage objects

4. Divided into three main categories--collections, lists and mappings

2. Class Set frame diagram

　　

Represents an interface for a dashed box, a representation of a solid wireframe implementation class

Main methods in the collection interface

　　

The main method in iterator is the Hasnext () and Next () methods

Example:

　　

How to use 3.Map and HashMap '

What is a map

　　

How to use 4.JDK help documents

The class set framework in Java