java技术博客

jsp博客
数据加载中……
java中的集合
Integer[] a = {3,25,12,79,48};
        System.out.println(a);
        System.out.println(Arrays.toString(a));
        Arrays.sort(a);
        System.out.println(Arrays.toString(a));
        int idx = Arrays.binarySearch(a,25);
        System.out.println(idx);
        
        List list = Arrays.asList(3,4,5);
        System.out.println(list);
        list.set(2,66);
        System.out.println(Arrays.toString(a));
TreeSet ts = new TreeSet();
        ts.add("orange");
        ts.add("banana");
        ts.add("apple");
        ts.add("grape");

        Iterator it = ts.iterator();
        while(it.hasNext()){
            String fruit = (String)it.next();
            System.out.println(fruit);    
HashSet h = new HashSet();
        h.add("1st");
        h.add("2nd");
        h.add(new Integer(3));
        h.add(new Double(4.0));
        h.add("2nd");          // 重复元素, 未被加入
        h.add(new Integer(3));     // 重复元素,未被加入
        h.add(new Date()); 
        System.out.println("开始: size=" + h.size());
        Iterator it = h.iterator();
        while(it.hasNext()){
            Object o = it.next();
            System.out.println(o);    
        }
        
        h.remove("2nd");
        System.out.println("移除元素后: size=" + h.size());
        System.out.println(h);
ArrayList h = new ArrayList();
        h.add("1st");
        h.add("2nd");
        h.add(new Integer(3));
        h.add(new Double(4.0));
        h.add("2nd");      // 重复元素, 加入
        h.add(new Integer(3)); // 重复元素,加入
        System.out.println(h);        
        System.out.println("size=" + h.size());
        System.out.println("-----替换指定元素-----");    
        h.set(3,"replace");        
        System.out.println("-----for循环遍历-----");
        for(int i=0;i<h.size();i++){
            System.out.println(h.get(i));
        }        
        System.out.println("-----取用特定元素-----");        
        Integer it = (Integer)h.get(2);
        System.out.println(it.intValue());
        System.out.println("-----插入元素-----");        
        h.add(3,new Date());
        System.out.println("-----转换为数组-----");    
        Object[] os = h.toArray();
        for(Object o : os){
            System.out.println(o);    




Vector v = new Vector();
        v.add("1st");
        v.add("2nd");
        v.add(new Integer(3));
        v.add(new Double(4.0));
        v.add("2nd");      // 重复元素, 加入
        v.add(new Integer(3)); // 重复元素,加入
        System.out.println(v);        
        System.out.println("size=" + v.size());
        System.out.println("-----替换指定元素-----");    
        v.set(3,"replace");        
        System.out.println("-----for循环遍历-----");
        for(int i=0;i<v.size();i++){
            System.out.println(v.get(i));
        }        
        System.out.println("-----取用特定元素-----");        
        Integer it = (Integer)v.get(2);
        System.out.println(it.intValue());
        System.out.println("-----插入元素-----");        
        v.add(3,new Date());
        System.out.println("-----转换为数组-----");    
        Object[] os = v.toArray();
        for(Object o : os){
            System.out.println(o);    




Stack s = new Stack();
        s.push("hello");
        s.push(new Date());
        s.push(400);  //自动封装,等价于s.push(new Integer(400));
        s.push(3.14);
        
        System.out.println("弹栈前:size=" + s.size());
        System.out.println(s.pop());
        System.out.println("弹栈后:size=" + s.size());
        System.out.println(s.peek());
        System.out.println("peek操作后:size=" + s.size());
        while(!s.isEmpty())
            System.out.println(s.pop());



ArrayList a = new ArrayList();
        a.add("China");
        a.add("USA");
        a.add("Korea");
        Iterator  it = a.iterator();
        while(it.hasNext()){
            String country = (String)it.next();
            System.out.println(country);    
        }        
        
        Vector v = new Vector();
        v.addElement(new Date());    
        v.addElement(new Date(200008755554L));
        it = v.iterator();
        while(it.hasNext()){
            Date time = (Date)it.next();
            System.out.println(time);    








import java.util.Vector;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Enumeration;

public class TestCollections{
    public static void main(String[] args) {
        ArrayList alist = new ArrayList();
        alist.add(75); 
        alist.add(38); 
        alist.add(21); 
        alist.add(4); 
        alist.add(12); 

        System.out.println("原列表: " + alist);
        Collections.sort(alist);
        System.out.println("排序后: " + alist);
        Collections.reverse(alist);
        System.out.println("逆序后: " + alist);
        Collections.shuffle(alist);
        System.out.println("混排后: " + alist);
        Collections.rotate(alist,2);
        System.out.println("移位后: " + alist);        
        
        ArrayList blist = new ArrayList();
        blist.add(55); 
        blist.add(66);
        System.out.println("新列表: " + blist);
        Collections.copy(alist,blist);
        System.out.println("拷贝后: " + alist);

        System.out.println("列表中出现元素66的次数: " + Collections.frequency(alist,66));
        System.out.println("列表中元素的最大值: " + Collections.max(alist));
        System.out.println("列表中元素的最小值: " + Collections.min(alist));

        Enumeration en = createDemoEnumeration();
        ArrayList clist = Collections.list(en);
        System.out.println("Enumeration->ArrayList: " + alist);
    }
    
    public static Enumeration createDemoEnumeration(){
        Vector v = new Vector();
        v.add("Tom");        
        v.add("Billy");        
        v.add("Jenny");        
        return v.elements();    
    }
}


posted on 2008-11-13 09:07 郭兴华 阅读(278) 评论(0)  编辑  收藏


只有注册用户登录后才能发表评论。
网站导航: