我正在尝试从 ArrayList 中的数组中获取随机项

Question

我正处于创建我认为本质上应该是一个简单的小程序的开始阶段。但是，我对 java 很陌生，所以事实证明它比预期的要困难。这就是我将编译的内容，除了最后的打印部分。首先，我不明白为什么不呢？其次，我需要创建一个随机生成器来从 arrayList 中的一个数组中随机选择一个项目。我一直在尝试很多东西，但就是无法让它发挥作用。我想我什至对将代码放在哪里感到困惑。帮助！

import java.util.*;

public class RestaurantSelector1 {

    //public static class Tribeca4star{
    final static String[] italian = {"Pepolino Restaurant", "Locanda Verde", "Scalini Fedeli", "Gran Morsi", "Ecco", "Tutto il Giorno", "The Odeon", "Mamo Restaurant", "Petrarca Cucina E Vino", "Osteria Morini"};
    final static String[] japanese = {"Shigure", "Sushi Azabu", "Ichimura", "Brushstroke", "Takahachi Tribeca Restaurant", "Ninja New York", "DOMODOMO", "Sushi of Gari", "Hirohisa", "Blue Ribbon"};
    final static String[] french = {"Bouley", "Batard", "Racines", "The Odeon", "MAMO Restaurant", "La Sirene", "Le Coucou", "Balthazar", "Taureau", "L'Appart"};
    final static String[] american = {"American Cut Steakhouse", "Marc Forgione", "The Bennett", "Little Park", "The Odeon", "Yves", "Tribeca Grill", "Atera", "Batard", "Brandy Library"};
    final static String[] chinese = {"Mr. Chow", "Macao", "Khe-Yo"};
    final static String[] spanish = {"Tablao", "Sazon", "Despana", "Estancia 460", "Westside Coffee Shop", "Anejo Tribeca", "Terra Wine Bar", "Darlene", "Sophia's Cuban Cuisine", "Amada"};
    final static String[] cafe = { "Arcade Bakery", "Galerie de Cafe", "The Wooly Daily", "Cafe Belle", "Baked", "Laughing Man Coffee and Tea","La Colombe Coffee", "Kuro-Obi at Canal Street Market", "Blue Spoon Coffee", "Everyman Espresso"};
    final static String[] thai = {"khe-yo", "Empire", "Macao"};
    final static String[] indian = {"Tamarind"};
    final static String[] viatnamese = {"Khe-Yo", "Macao"};

    public static void main(String[] args){
        ArrayList<String[]> cuisine = new ArrayList<>();

        cuisine.add(italian);
        cuisine.add(japanese);
        cuisine.add(french);
        cuisine.add(american);
        cuisine.add(chinese);
        cuisine.add(spanish);
        cuisine.add(cafe);
        cuisine.add(thai);
        cuisine.add(indian);
        cuisine.add(viatnamese);

        System.out.println(cuisine[0,1]);
    }
}

Answer 1

您可以通过创建一个新的 Random() 实例并从 nextInt、[0,cuisine.size()) 和 [0,cuisine.get(rnd).length) 获取随机 int 来生成随机索引

Random rand = new Random();                         //RN Generator
int rnd     = rand.nextInt(cuisine.size());         //random lang index
int rndWord = rand.nextInt(cuisine.get(rnd).length) //random word index

然后您可以使用带有.get(rnd) 的随机索引来访问您想要的String[]，并使用[rndWord] 获取该数组中的随机条目。

System.out.print( cuisine.get(rnd)[rndWord] );      //print out random word

Answer 2

试试System.out.println(cuisine.get(0)[1])

您想使用ArrayList.get(int index) 来检索您的String[] 对象，然后您可以指向该数组中的字符串

Answer 3

要从随机菜系中获取随机餐厅，您可以执行以下操作：

final Random random = new Random();
final String[] randomCuisine = cuisine.get(random.nextInt(cuisine.size()));
final String randomRestaurant = randomCuisine[random.nextInt(randomCuisine.length)];

Answer 4

如果我对您的理解正确，您希望从列表中随机获得一个String[]，然后从String[] 中获得一个随机条目。您可以通过使用 java.util.Random 类来获得它：

public static String getRandom(List<String[]> list) {
    Random random = new Random();
    int listAccess = random.nextInt(list.size());
    String[] s = list.get(listAccess);
    return s[random.nextInt(s.length)];
}

然后，只需将System.out.println(cuisine[0,1]); 替换为

System.out.println(getRandom(cuisine));

对于您的代码为什么无法编译的问题，这是因为您必须使用 .get(<index>) 来获取 List，并使用 [<index>] 来访问数组中的项目。

Answer 5

首先，你的 import 语句不会像写的那样编译。

import java.util.; //will not compile without class name after '.' import java.util.*; //will compile: You could also specify a specific class name in place of the *

至于生成随机餐厅，您可以通过将以下代码添加到您的 main 方法来实现。我已经添加了 cmets 进行解释。

public static void main(String[] args) {
    ArrayList<String[]> cuisine = new ArrayList<>();

    cuisine.add(italian);
    cuisine.add(japanese);
    cuisine.add(french);
    cuisine.add(american);
    cuisine.add(chinese);
    cuisine.add(spanish);
    cuisine.add(cafe);
    cuisine.add(thai);
    cuisine.add(indian);
    cuisine.add(viatnamese);

    Random randomArrayListIndex = new Random();

    int randomCuisine = randomArrayListIndex
            .nextInt(cuisine.size());

    String[] randomArray = cuisine.get(randomCuisine); // get random array
                                                        // from ArrayList

    Random randomArrayIndex = new Random();

    String randomRestaurant = randomArray[randomArrayIndex // get random element
                                                        // from array
            .nextInt(randomArray.length)];
    System.out.println(randomRestaurant);
}