1 public class Demo {
 2     public static void main(String[] args) {
 3         List list = Arrays.asList(5,2,3,1,9);
 4         int N = list.size();
 5         int t = 0;
 6         Collections.sort(list);
 7 //        Collections.reverse(list); 逆序
 8 //        Collections.shuffle(list); 隨機
 9         boolean
 
 flag = true;
10         for(int i=0; i<list.size()-1 ; i++){
11             int a = (int)list.get(i+1);
12             int b = (int)list.get(i);
13             int c = a - b;
14             if(c != 1){
15                 flag = false;
16                 System.out.print("數字不連續哦");
17                 break
 
;
18             }
19         }
20         System.out.println(flag);
21     }
22 }

Collections類裏好多方法，具體，自己讀API吧

判斷一組數字，是否連續