java vector 使用

建立一个一维的vector:

Vector<Double> v=new Vector<Double>();//实例一个v对象
v.addElement();//在v中添加元素的方法
v.elementAt(i);//取得v中索引为i的元素

c++的 vector使用不需要new

vector<int> v(10);

 

vector向末尾添加元素有2种方法，add和addElement，有什么区别呢？

add() comes from the List interface, which is part of the Java Collections Framework added in Java 1.2.Vector predates that and was retrofitted with it. The specific differences are:

1. addElement() is synchronized. add() isn't. In the Java Collections Framework, if you want these methods to be synchronized wrap the collection in Collections.synchronizedList(); and

2. add() returns a boolean for success. addElement() has a void return type.

The synchronized difference technically isn't part of the API. It's an implementation detail.

Favour the use of the List methods. Like I said, if you want a synchronized List do:

List<String> list =Collections.synchronizedList(newArrayList<String>());
list.add("hello");
via：http://stackoverflow.com/questions/3089969/difference-between-javas-vector-add-and-vector-addelement
区别基本可以忽略。

vector创建2维数组：

 

Vector<Vector<Double>> v=new Vector<Vector<Double> >();

//Example: get(0,2)

Double d=v.get(0).get(2);

new <? >表示泛型。

 
从jdk5.0开始，新增了泛型功能。泛型可以使把你的定义的对象置于某个容器而不失去其类型。也可以定义泛型类，public class classname <T> {}