public vector() 
public vector(int initialcapacity,int capacityIncrement) 
public vector(int initialcapacity) 

（1）public final synchronized void adddElement(Object obj) 

Vector v1 = new Vector(); 
Integer integer1 = new Integer(1); 
v1.addElement(integer1); 

import java.util.Vector;  
import java.lang.*;  
import java.util.Enumeration;  
public class VectorApp  
{  
   public static void main(String args[])  
   {  
     Vector v1 = new Vector();  
     Integer integer1= new Integer(1);  
     //加入为字符串对象  
     v1.addElement("one");  
     //加入的为integer的对象  
     v1.addElement(integer1);  
     v1.addElement(integer1);  
     v1.addElement("two");  
     v1.addElement(new Integer(2));  
     v1.addElement(integer1);  
     v1.addElement(integer1);  
     //转为字符串并打印  
      System.out.println("The Vector v1 is:\n\t"+v1);  
     //向指定位置插入新对象  
     v1.insertElement("three",2);  
     v1.insertElement(new Float(3.9),3);  
     System.out.println("The Vector v1(used method  
     insertElementAt()is:\n\t)"+v1);  
     //将指定位置的对象设置为新的对象  
      //指定位置后的对象依次往后顺延  
      v1.setElementAt("four",2);  
      System.out.println("The vector v1 cused method setElmentAt()is:\n\t"+v1);  
      v1.removeElement(integer1);  
      //从向量对象v1中删除对象integer1  
      //由于存在多个integer1,所以从头开始。  
       //找删除找到的第一个integer1.  
      Enumeration enum = v1.elements();  
      System.out.println("The vector v1 (used method removeElememt()is");  
      while(enum.hasMoreElements())  
      System.out.println(enum.nextElement()+"");  
      System.out.println();  
      //使用枚举类(Enumeration)的方法取得向量对象的每个元素。  
       System.out.println("The position of Object1(top-to-botton):"+v1.indexOf(integer1));  
      System.out.println("The position of Object1(tottom-to-top):"+v1.lastIndexOf(integer1));  
      //按不同的方向查找对象integer1所处的位置  
       v1.setSize(4);  
      System.out.println("The new Vector(resized the vector)is:"+v1);  
      //重新设置v1的大小，多余的元素被抛弃   
   }  
}  

E:\java01>java VectorApp 
The vector v1 is:[one,1,1,two,2,1,1] 
The vector v1(used method insetElementAt()) is: 
[one,1,three,3.9,1,two,2,1,1] 
The vector v1(used method setElementAt()) is: 
[one,1,four,3.9,1,two,2,1,1] 
The vector v1(useed method removeElement()) is: 
one four 3.9 1 two 2 1 1 
The position of object1(top-to-botton):3 
The position of object1(botton-to-top):7 
The new Vector(resized the vector) is: 
[one,four,3.9,1] 

public final int size(); 

public final synchronized void setsize(int newsize); 

public final synchronized Enumeration elements();