判斷一組數字，是否連續

public class Demo {
    public static void main(String[] args) {
        List list = Arrays.asList(5,2,3,1,9);
        int N = list.size();
        int t = 0;
        Collections.sort(list);
//        Collections.reverse(list); 逆序
//        Collections.shuffle(list); 隨機
        boolean flag = true;
        for(int i=0; i<list.size()-1 ; i++){
            int a = (int)list.get(i+1);
            int b = (int)list.get(i);
            int c = a - b;
            if(c != 1){
                flag = false;
                System.out.print("數字不連續哦");
                break;
            }
        }
        System.out.println(flag);
    }
}

Collections類里好多方法，具體，自己讀API吧