1.Enumeration接口
boolean hasMoreElements( )
Object nextElement( )
2.Vector 类
创建
Vector()
Vector(int size)
Vector(int size,int incr) incr 每次增加的元素数量
追加元素:
void add(int index, Object element)
boolean add(Object o)
boolean addAll(Collection c)
boolean addAll(int index, Collection c)
返回容量:
int capacity()
判断元素是否存在
boolean contains(Object elem)
复制到数组:
void copyInto(Object[] anArray)
返回向量的枚举
Enumeration elements()
size()
import java.util.*; public class VectorDemo { public static void main(String args[]) { // initial size is 3, increment is 2 Vector v = new Vector(3, 2); System.out.println("Initial size: " + v.size()); System.out.println("Initial capacity: " + v.capacity()); v.addElement(new Integer(1)); v.addElement(new Integer(2)); v.addElement(new Integer(3)); v.addElement(new Integer(4)); 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(7)); System.out.println("Current capacity: " + v.capacity()); v.addElement(new Float(9.4)); v.addElement(new Integer(10)); System.out.println("Current capacity: " + v.capacity()); v.addElement(new Integer(11)); v.addElement(new Integer(12)); System.out.println("First element: " + (Integer)v.firstElement()); System.out.println("Last element: " + (Integer)v.lastElement()); if(v.contains(new Integer(3))) System.out.println("Vector contains 3."); // enumerate the elements in the vector. Enumeration vEnum = v.elements(); System.out.println("\nElements in vector:"); while(vEnum.hasMoreElements()) System.out.print(vEnum.nextElement() + " "); System.out.println(); } }
输出结果:
Initial size: 0 Initial capacity: 3 Capacity after four additions: 5 Current capacity: 5 Current capacity: 7 Current capacity: 9 First element: 1 Last element: 12 Vector contains 3. Elements in vector: 1 2 3 4 5.45 6.08 7 9.4 10 11 12
3.栈stack vector的子类
empty()
peek() 查看顶部对象
pop()
push(Object e)
int search(Object element) //返回对象在堆栈中的位置,以 1 为基数。
import java.util.*; public class StackDemo { static void showpush(Stack<Integer> st, int a) { st.push(new Integer(a)); System.out.println("push(" + a + ")"); System.out.println("stack: " + st); } static void showpop(Stack<Integer> st) { System.out.print("pop -> "); Integer a = (Integer) st.pop(); System.out.println(a); System.out.println("stack: " + st); } public static void main(String args[]) { Stack<Integer> st = new Stack<Integer>(); System.out.println("stack: " + st); showpush(st, 42); showpush(st, 66); showpush(st, 99); showpop(st); showpop(st); showpop(st); try { showpop(st); } catch (EmptyStackException e) { System.out.println("empty stack"); } } }
输出
stack: [ ] push(42) stack: [42] push(66) stack: [42, 66] push(99) stack: [42, 66, 99] pop -> 99 stack: [42, 66] pop -> 66 stack: [42] pop -> 42 stack: [ ] pop -> empty stack