java 动态数组

package testjavapro;
import java.util.*;

public class testjava {

   public static void main(String args[]) {
      // initial size is 3, Capacity increment is 2
      Vector<Number> v = new Vector<Number>(, );
      System.out.println("Initial size: " + v.size());
      System.out.println("Initial capacity: " +
      v.capacity());
      v.addElement(new Integer());
      v.addElement(new Integer());
      v.addElement(new Integer());
      v.addElement(new Integer());
      System.out.println("Capacity after four additions: " +
          v.capacity());

      v.addElement(new Double(5.45));
      System.out.println("Current capacity: " +
      v.capacity());
      v.addElement(new Double(6.08));
      v.addElement(new Integer());
      System.out.println("Current capacity: " +
      v.capacity());
      v.addElement(new Float(9.4));
      v.addElement(new Integer());
      System.out.println("Current capacity: " +
      v.capacity());
      v.addElement(new Integer());
      v.addElement(new Integer());
      System.out.println("First element: " +
         (Integer)v.firstElement());
      System.out.println("Last element: " +
         (Integer)v.lastElement());
      if(v.contains(new Integer()))
         System.out.println("Vector contains 3.");
      // enumerate the elements in the vector.
      Enumeration<Number> vEnum = v.elements();
      System.out.println("\nElements in vector:"+v.size());
      while(vEnum.hasMoreElements())
         System.out.print(vEnum.nextElement() + " ");
      System.out.println();
   }
}

输出

Initial size:
Initial capacity:
Capacity after four additions:
Current capacity:
Current capacity:
Current capacity:
First element:
Last element:
Vector contains .

Elements in vector:
    5.45 6.08  9.4