List排序Collections.sort 重写compare

 1 static List<Integer> intList = Arrays.asList(2,5,7, 3, 1);
 2 
 3       public static void main(String[] args) { 
 4           
 5           System.out.println(\"before sort:\");
 6             PrintUtil.showList(intList);
 7             System.out.println(\"=========================\");
 8             Collections.sort(intList,new Comparator<Integer>() {
 9 
10                 public int compare(Integer o1, Integer o2) {
11                     // 返回值为int类型，大于0表示正序，小于0表示逆序
12                     System.out.println(\"o2-o1:\"+(o2-o1)+\"========o2=\"+o2+\"o1=\"+o1);
13                     if(o2>o1){
14                         return -1;    
15                     }else{
16                         return 1;    
17                     }
18                 }
19             });
20             System.out.println(\"after sort:\");
21             PrintUtil.showList(intList);
22           
23     }