java - 仅接受用户对 ArrayList 的唯一输入

Question

我不知道如何只允许用户输入三个唯一的数字。我尝试创建另一个数组来添加输入并检查损坏数组以确保所有数字都是唯一的，但它似乎不起作用。感谢您的任何帮助!!

    ArrayList<Integer> damage = new ArrayList<Integer>();

    ArrayList<Integer> unique = new ArrayList<Integer>();
    for (int k = 0; k<=10; k++)
    {
        unique.add(k);
    }
    do
    {
        System.out.print("Attack or Defend? (A or D) ");
        option = keyboard.nextLine().toUpperCase();
        System.out.println();
        switch (option) 
        {
            case "A":
                System.out.println("Enter three unique random numbers (1-10)");
                for(int i = 0; i<3; i++)
                {
                    System.out.print("number " + (i+1) + ": ");
                    input = keyboard.nextInt();
                    if (input < 1 || input > 10)
                    {
                        System.out.println("Error! Enter a valid number (1-10)");
                    }
                    else 
                    {
                       if (unique.contains(input))
                       {
                           unique.remove(input);  
                           System.out.println(unique);
                           damage.add(input);
                           System.out.println(damage);

                           i--;
                       }                           
                       else 
                       {
                           unique.add(0, input);
                           System.out.println("Number is not unique!");
                       }

                    }
                 }
                System.out.println(damage);
                System.out.println();
                UserDamage ahit = new UserDamage(damage, option);
                name.getName();
                ahit.setUserDamage(damage, option);
                System.out.println("\n");
                cpuHealth-=ahit.getUserDamage();
                cpu.setCpuDamage();
                userHealth-=cpu.getCpuDamage();
                System.out.println("\n\nHealth left: " + userHealth);
                System.out.println("Computer health left: " + cpuHealth + "\n");
                damage.clear();
                option = null;
                break;


            default:
                System.out.println("Invalid selection.");
                break;
        }
    }
    while(userHealth>0 || cpuHealth >0);

Answer 1

使用 java.util.List 中的 contains 方法来确定该项目是否已存在。来自 Javadoc:

boolean contains(Object o)

Returns true if this list contains thespecified element. More formally, returns true if and only if thislist contains at least one element e such that (o==null ? e==null :o.equals(e)).