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Collections笔记

Colletion是集合接口

Collections是集合工具类,是一个类哈!

public class CollectionsTest {    public static void main(String[] args) {        List list = new ArrayList();        list.add(4);        list.add(3);        list.add(9);        list.add(3);        list.add(10);        list.add(1);                for (Iterator it = list.iterator() ; it.hasNext() ;){            System.out.println(it.next());        }        //对list进行排序        Collections.sort(list);                System.out.println("------------");        for (Iterator it = list.iterator() ; it.hasNext() ;){            System.out.println(it.next());        }                Set set = new HashSet();        set.add(3);        set.add(10);        set.add(199);        set.add(1);        set.add(44);        set.add(199);        //Sort方法不能对set排序,所以先把Set转换成List        List l = new ArrayList(set);        Collections.sort(l);        System.out.println("------------");        for (Iterator it = l.iterator() ; it.hasNext() ;){            System.out.println(it.next());        }                //将ArrayList转换成线程安全的        List syncList = Collections.synchronizedList(list);    }}

 

4
3
9
3
10
1
------------
1
3
3
4
9
10
------------
1
3
10
44
199

Collections笔记