分支语句 - 升序或降序整数

Question

Been studying Java for a few months now with no prior development experience, but I am determined to learn this. This is my first post. Here's the question:

Write a program that reads a sequence of integer numbers and outputs true if the sequence is ordered (in ascending or descending order), otherwise, false. Keep in mind, if a number has the same value as the following number, it does not break the order. The sequence ends with 0. Do not consider this number as a part of the sequence. The sequence always has at least one number (excluding 0).

Sample Input 1: 9 8 7 6 5 4 3 2 1 0

Sample Output 1: true

Sample Input 2: 1 2 3 3 9 0

Sample Output 2: true

Sample Input 3: 1 2 5 5 2 3 0

Sample Output 3: false

I've read other posts that addresses this issue, but my code is a representation of the concepts I've learned and quasi-understand thus far. My intuition is that in order to iterate through all the values that are input BEFORE producing a 'true' or 'false', a list is probably needed. But, I'm unsure of how to utilize Scanner within a list and how to use a list within a 'for loop' &/or 'if' statements. Here is my code thus far, which is producing a error of time limit exceeded. Thank you in advance for your help.

import java.util.Scanner;

class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int input = scanner.nextInt();

        for (int i = 1; i > 0; i++) {

            if (input >= i || input == i + 1) {
            System.out.println(true); 
            }  
            else if (input <= i || input == i - 1) {
            System.out.println(true);
            }
            else {
            System.out.println(false);
            }
        }   
    }
}

Answer 1

Let's first read in all the numbers:

Scanner scanner = new Scanner(System.in);
List<Integer> numbers = new ArrayList<>(); //use a list to store
int number = -1;
while(number != 0) { //go until 0
    System.out.println("Enter a positive int or 0 to stop!");
    number = scanner.nextInt(); //read integer
    if(number != 0) {
        numbers.add(number); //save it, but only if it's not 0
    }
}

Now we have all numbers in the list. Some methods can be writter to check if they are ascending:

public static boolean isAscending(List<Integer> numbers) {
    int number, next;
    if(numbers.size()==1) return true; // edge cases
    if(numbers.size()==2) {
       return numbers.get(0) <= numbers.get(1);
    }
    for(int i=0; i<numbers.size() - 2; i++) { //from first to one before last
        number = numbers.get(i);
        next = numbers.get(i+1);
        if(next < number) { //next is NOT bigger then the current (equal accepted)
            return false;        
        }
    }
    return true; //if we got here then it's ascending
}

The descending method is similar, but you use '>' when comparing the numbers. Then, it's just a matter of calling them on the input list:

boolean ascending = isAscending(numbers);
boolean descending = isDescending(numbers);
if(ascending || descending) {
    //result is TRUE here
    System.out.println("TRUE");
} else {
    //result is FALSE here
    System.out.println("FALSE");
}