Organization of Java object groups: vector vectors

Functions of vectors:

1. can store any object

2. Cannot store basic types of data, such as 39, unless the data is wrapped in a parcel class

3. Its capacity can be automatically expanded according to demand

4. Increase the efficiency of the element method if the capacity is not expanded

Way:

Vector myvector=new vector ()///initial capacity of 10

Vector myvector=new vector (int cap)//initial capacity is cap

Vector myvector=new Vector (Collection col)//using the elements of the collection Col to initialize, and if you col an array, you need to convert it to a list object first

Example: Vector myvector=new vector (arrays.aslist (col));

void Add (Object obj)//Adds the given parameter object to the last of the vector's original element

Boolean AddAll (colletion col)//Adds all elements in the collection class object to the recipient object of this method, returns true if the recipient's result is changed

int size ()//Returns the number of elements

Boolean isempty ()//Determine whether the vector is empty

Object get (int pos)//return element at specified position

void set (int pos,object obj)//Replace an object in the vector with the position pos

Boolean remove (Object obj)//deletes the first obj object found, returns true. False if not found

Objectremove (int pos)//remove element from a given position and return the object being removed

Boolean RemoveAll (Collection col)//Delete all objects in the vector that appear in Col, return true if the recipient's result is changed

void clear ()//delete all elements of a vector

Boolean contain (Object obj)//Determine whether the vector contains obj

Boolean containall (Collection col)//Determine whether the vector contains all the elements in Col

int indexOf (Object obj)//returns the position of obj at the first occurrence of the vector and returns 1 if it is not found

Enumeration elements ()//Returns the enumeration object for all elements in the vector, noting that this method cannot be used for ArrayList

Iterator iterator ()//Return iterator object for all elements in vector

Special Note: Object get (int pos)//Read position is the element of POS, because it returns an object, so it needs to be plastic (explicit conversion)

Cases:

for (int i=0;i<v.size (); i++)

Custmer c= (Custmer) v.get (i); Every object read from V needs to be explicitly converted before it can be used correctly.