One, Javase (15) Object array, collection (Collection), collection (List)

1: Object Array ( master )

(1) arrays can store both basic data types , You can also store reference types. It is called an array of objects when it stores the reference type.

(2) Case :

Stores 5 student Objects in an array , and iterates through the array.

2: Collection (Collection) ( master )

(1) The origin of the collection ?

We are learning java-- Object-oriented -- manipulating many objects - - storage -- containers ( arrays and stringbuffer)-- Arrays

While the length of the array is fixed , so it is not suitable for changing requirements , Java provides a collection for us to use

(2) the difference between a collection and an array ?

A: Length Difference

Array pinning

Set Variable

B: Content Differences

An array can be a base type , or it can be a reference type

Collections can only be reference types

C: element Content

Arrays can only store the same type

Collections can store different types ( In fact, collections typically store the same type )

(3) Inheritance architecture for collections ?

Because of the different requirements , Java provides different collection classes. The data structure of these multiple collection classes is different , But they are all to provide storage and pass-through functions ,

We extract the generality of them continuously , and finally form the inheritance architecture of the set .

Collection

|--list

|--arraylist

|--vector

|--linkedlist

|--set

|--hashset

|--treeset

(4) Collection Overview of features (self- completed )

A: Add features

B: Remove Features

C: Judging function

D: Get features

E: length function

F: intersection ( learn )

G: Turn the set to a number ( learn )

(5) Collection the pass calendar of the collection

A: Turn the set to a number ( learn )

B: iterators (Collection- specific method )

(6) iterators

A: is the way the collection gets the elements

B: is a collection-dependent existence.

C: the principle and source of the iterator

A: why define for an interface instead of implementing a class ?

B: look at the inner class implementation of the iterator .

(7) Collection Collection of cases (Traversal- mode iterator )

Procedure for collection:

A: Create a collection

B: Creating an Element object

C: adding elements to the collection

D: iterating through the collection

A: store characters and pass the calendar

B: Store custom objects and traverse

3: Collection (List) ( master )

(1) List is a co11ection the sub-interface

features : ordered ( same order of storage and removal ), repeatable ;

(2) List Unique features of :( Self -completion )

A: Add features

B: Remove Features

C: Get features

D: iterator Capabilities

E: Modifying features

(3) List unique traversal capabilities for collections

A: by size () and the get () combined

(4) Unique features of list iterators :( Understand )

It can be traversed in reverse , but it must be traversed first , so it makes no sense , basically does not use

(5) Concurrency Modification Exceptions

A: phenomena that occur

iterators iterate through collections , Collections Modify collection Elements

B: cause

The transmitter is dependent on the collection , and the set of changes to the surrogate does not know

C: Solution Solutions

A: Iterator Event Calendar , Iterator Modification (Listiterator)

element is added at the location of the iteration just

B: Collection Pass Calendar , Collection Modification (Size () and get ())

element is added to the end of the collection

(6) Common data Structures

A: Stack Advanced post-out

B: Queue Advanced First Out

C: Array Query Fast , Delete Slow

D: Linked list Slow Query , Quick and Delete

(7) Five is T sub-class characteristics ( face Test )

Arraylist

the underlying data structure is a number of groups , query Fast , and Delete slowly

thread insecure , High efficiency

Vector

the underlying data structure is an array , query Fast , and Delete steamed bread

Thread-safe , low-efficiency

LinkedList

the underlying data structure is linked list , query slow , Delete quickly

thread insecure , high efficiency A

who do you use it for ? See demand ?

Analysis :

Are you safe ?

to : Vector ( Even if you want to , do not use this , after the /c13>)

do not : Arraylist or linkedlist

Query more : Arraylist

More additions and deletions : LinkedList

don't know anything , just use Arraylist .

One, Javase (15) Object array, collection (Collection), collection (List)