41. Class set Framework (i)

Learning Essentials:

1. What is a class set framework

2. Types of collections

3. The basic mechanism of the class set framework

What is a class set framework

1. A class set framework is a set of classes and interfaces

2. Located in the Java.util bag;

3. The primary user stores and manages objects;

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

What is a collection (set)

The objects in the collection have no order and no duplicate objects

What are lists (list)

Objects in the collection are sorted by index location and can have duplicate objects

What is mapping (map)

Each element in the collection contains a key object and a value object, the key cannot be duplicated, and the value can be repeated

Import Java.util.list;import java.util.arraylist;interface test{public static void Main (String args[]) {arraylist< string> arrayList = new arraylist<string> () Arraylist.add ("a");//Add Data Arraylist.add ("B"); Arraylist.add ("C" ); Arraylist.remove (1); Delete element ' B ' for (int i = 0; Arraylist.size (); i++) {String s = arraylist.get (1); System.out.println (s);}}}

41. Class set Framework (i)