为什么 boolean 值不注册为真？

Question

I am creating a shopping list program where it will ask the user for a list of input of pantry items. After that, the computer will compare the user's input and a pre-determined list of pantry items to see if the user got everything needed. Finally, it will either print out "You got everything," or "you still need something" plus the item missing.

This is the code I have, and everything works just fine, except one tiny error.

import java.util.*;

public class TheList
{
    public static void main(String args[])
    {
        //scanner for user input
        Scanner scan = new Scanner(System.in);
        
        //pantry
        ArrayList<String> pantry = new ArrayList<String>();
        pantry.add("Bread");
        pantry.add("Peanut Butter");
        pantry.add("Chips");
        pantry.add("Jelly");
        
        //user input
        ArrayList<String> input = new ArrayList<String>();
        while(true)
        {
            System.out.println("Please enter an ingredient ('done' when complete): ");
            String userInput = "";
            if (scan.hasNextLine())
            {
                userInput = scan.nextLine();
            }
            if (userInput.equals("done"))
            {
                break;
            }
            input.add(userInput);

        }
        
        //print out result
        boolean shoppingDone = input.contains(pantry);
        if (shoppingDone == true) {
            System.out.println("It looks like you have everything to make your recipe!");
        }
        else {
            pantry.removeAll(input);
            System.out.println("You need to go shopping!");
            System.out.println("The following ingredients are missing:");
            System.out.println(pantry);
        }
    }
}

My boolean value doesn't register as true, even if all elements from pantry list is contained in the input list. Why is that?

Answer 1

ArryList.contains() checks if a particular object is present in the collection. You probably want to use the containsAll method.