java - 从单独的 Java 主类打印 ArrayList

Question

我的作业有很多问题，而我似乎唯一遇到麻烦的是 ArrayList 问题。我需要使用单独的 main 方法来输入和打印信息。

这是我的课

import java.util.ArrayList;

public class HailstoneSequence {

private int n;

public HailstoneSequence(int n) {
    this.n = n; 
}

public double getn() {
    return n;
}

    public static ArrayList<Integer> getHailstoneSequence(int n){
        ArrayList<Integer> list = new ArrayList<Integer>();
        //int i = 0; 
        while (n != 1);
        for (int s : list) {
            try {
            if(n == 1) break;   
            if(n % 2 == 0) {
                System.out.println(n + " is even, so I take half: " + (n / 2));
            }
            else 
                System.out.println(n + " is odd, so I make 3n+1: " + ((n * 3)+1));
           // i++;
            }
            catch (Exception error) {
                while (n <= 1) {

                    System.out.println("You did not enter a valid positive, greater than 1 integer. Please try again: ");
                    System.out.println();

                }
             }   
        }
        return list;
    }
}  

这是主类(不起作用)

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Scanner;


public class TestHailstoneSequence {

    @SuppressWarnings("resource")
    public static void main(String[]args){    

        Scanner input = new Scanner(System.in);

        System.out.println("The Hailstone Sequence takes a number and if it odd it multiples it by 3 and adds 1,"
                + "\nit divides it by 2 and carries on until it reaches 1. \nPlease enter a positive number"
                + " (greater than 1) to generate the Hailstone Sequence: ");

        int n = input.nextInt();

        HailstoneSequence aHailstoneSequence = new HailstoneSequence(n);

        System.out.println(Arrays.toString(aHailstoneSequence.list));

         }
    }

请帮助我了解如何打印结果

Answer 1

您将 getHailstoneSequence 方法声明为静态方法，如果您需要在另一个操作中进行打印，则应该调用它并将其存储到变量中，如下所示:

ArrayList<Integer> list = HailstoneSequence.getHailstoneSequence(n);
System.out.println(list);