java - 打印从数组列表中随机删除的元素，然后打印更新后的数组列表

Question

因此，我在从数组列表中打印随机选择的元素，然后打印更新后的数组列表(其中不包含该随机元素)时遇到问题。每次我打印更新的列表时，它都会给出数组列表减去随机选择的元素并减去另一个元素。

import java.util.ArrayList;
import java.util.Scanner;
import java.util.Random;

public class LabPartyGuests   {
   public static void main(String[] args) {
      int numberOfGuests = 4;
      Scanner input = new Scanner(System.in);
      Random rand = new Random();
      ArrayList<String> guestList = new ArrayList<String>();

      System.out.println("Please enter 4 guests: ");
      System.out.print("guest1: ");
      String guest1 = input.nextLine();
      System.out.print("guest2: ");
      String guest2 = input.nextLine();
      System.out.print("guest3: ");
      String guest3 = input.nextLine();
      System.out.print("guest4: ");
      String guest4 = input.nextLine();

      for (int i = 0; i <= 0; i++)   {
         guestList.add(guest1);
         guestList.add(guest2);
         guestList.add(guest3);
         guestList.add(guest4);
      }
      System.out.println();
      System.out.print("Guest list: " + guestList);
      System.out.println();

      guestList.remove(rand.nextInt(4));
      System.out.printf("%s can't come %n", guestList.remove(rand.nextInt(4)));
      for (int i = 0; i < guestList.size(); i++)   {
         guestList.size();
      }  
      System.out.print(guestList);
   }
}

Answer 1

您要删除两个元素:

  guestList.remove(rand.nextInt(4)); // one
  System.out.printf("%s can't come %n", guestList.remove(rand.nextInt(4))); // two

如果要打印删除的元素，请存储第一次删除的输出，而不是调用删除两次:

  String removed = guestList.remove(rand.nextInt(4));
  System.out.println("removed element " + removed);