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ArrayList is the most common implementation of the List interface in the java collection framework. However, ArrayList allows identical elements to be stored. Although java has another Set called Set, it is used to store non-repeated elements.

1. arraylist Overview: Arraylist is a variable array implementation of the List interface. All optional list operations are implemented, which can include any element of null. In addition to the List interface, this class also provides some methods

The methods in java collection _ collection are embodied through Arraylist, And the java collection arraylist Import java. util .*;/*Collection defines the common functions of the Collection framework.1. AddAdd (e );AddAll (collection );2.

Generate 6 1 ~ Random integer between 33, add to the set, and traverse Package arraylist; import java. util. arraylist; import java. util. Random;/** train of thought * 6 ---> 6. fori * 1 ~ Between 33 ---> XXX. nextint (33) + 1; * random integer --->

Tag: obj means swap print 1.5 long can learning 5.5Reference data typeReference data type classification, refers to reference data type (class), in fact, we are not unfamiliar with it, such as the use of the scanner class, the random class.We can

ArrayList CollectionThe JDK provides a series of special classes that can store any type of element and are variable in length, collectively referred to as a collection.The ArrayList collection is the most common collection in a program, which

Packageentity; Public classNewtitle {Private intId//ID PrivateString TitleName;//name PrivateString creater;//created by PublicNewtitle () {} PublicNewtitle (intID, String titlename, String creater) { This. ID =ID; This. TitleName

1.1creation of collectionsTo create a common format for a collection:Guide Package:import java.util.ArrayList;To create an object: is identical to other common reference data types, but specifies the type of data stored in the container:

Collection frame: CollectionWhy are there so many containers?Because each container has a different way of storing the data,This storage method is called: Data structureCollectiondemoCreates a collection container. Using subclasses of the collection

Java Tour (18)--Basic data type Object wrapper class, collection frame, data structure, collection,arraylist, iterator iterator,list use Java defines all things as objects, and we want to use data types that can be referenced. I.