1         java.util.List<Integer> numbers=Arrays.asList(12,5,6,8,11,4);

 2         Collections.sort(numbers);//排序

 3         System.out.println(numbers);

 4         Collections.reverse(numbers);//反转

 5         System.out.println(numbers);

 6         Collections.shuffle(numbers);//打乱顺序

 7         System.out.println(numbers);

 8         //最大值、最小值

 9         Collections.max(numbers);

10         Collections.min(numbers);

1         java.util.List<String> list=Collections.synchronizedList(new ArrayList<String>());

2         Map<Integer, String> map=Collections.synchronizedMap(new HashMap<Integer,String>());

        java.util.List<String> words=Collections.unmodifiableList(new ArrayList<String>());