Printing ArrayList from a separate main class Java

Question

I have an Assignment that has many questions and the only ones I seem to be having trouble with are the ones with ArrayLists. I need to use a separate main method to enter and print out information.

This is my class

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;
    }
}  

and this is the main class (which does not work)

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));

         }
    }

Please help me understand how to print out the results

Answer 1

You declared getHailstoneSequence method as static one you should call it and store to a variable if you need in another operation and printing like this:

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

Answer 2

For your current case the main method will look something like this:

import java.util.Scanner;


public class TestHailstoneSequence {

    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();
        input.close(); // do not forget to close the resource

        // if you use static method in your HailstoneSequence class you can remove
        // field with name "n" from that class and you don't need to create an object in this case
        // Also I'd rename the class from HailstoneSequence to something like HailstoneSequenceCalculator
        System.out.println(HailstoneSequence.getHailstoneSequence(n));

    }
}