我想從一個ArrayList中的數組中獲得一個隨機項目

Question

我正處於創建我認爲本質上應該是一個簡單的小程序的開始階段。不過，我對java很陌生，所以它被證明比預期更困難。這是我所能編譯的，除了最後的打印部分之外。首先，我不明白爲什麼不呢？其次，我需要創建一個隨機生成器，從arrayList中的一個數組中隨機選擇一個項目。我一直在嘗試這麼多事情，但卻無法實現。我覺得我很困惑，甚至把代碼放在哪裏。幫幫我！

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

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

你想用ArrayList.get(int index)爲了找回您的String[]對象，然後你可以通過創建一個數組內的指向字符串

Answer 2

您可以生成一個隨機指數新的隨機（）實例，並從nextInt,[0,cuisine.size())獲得隨機int的隨機語言和[0,cuisine.get(rnd).length)該語言內的單詞

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 

然後，您可以使用隨機索引.get(rnd)來訪問您想要的String []，並獲得該數組中的隨機條目[rndWord]。

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

Answer 3

爲了得到一個隨機美食隨機的餐廳，你可以做到以下幾點：

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

Answer 4

如果我理解正確的話，你希望得到您的列表中隨機String[]，然後得到一隨機輸入出String[]。你可以通過使用java.util.Random類：

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)]; 
} 

然後，只需將System.out.println(cuisine[0,1]);與

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

對於你的問題，爲什麼你的代碼不能編譯取代，這是因爲你必須使用.get(<index>)爲List和[<index>]訪問數組中的項目。

Answer 5

首先，您的導入語句不會按照書面進行編譯。

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 *

作爲生成一個隨機的餐廳，你可以通過添加如下代碼到你的主要方法做到這一點。我已添加了解釋說明。

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); 
} 

Answer 6

如何從意大利語中獲得隨機餐廳？除了最後一行之外，所有的東西都編譯完成，我不知道如何獲得一種特定類型的美食，然後是一個隨機的餐廳。

ArrayList<String[]> WestVillageCuisine = new ArrayList<String[]>(); 
WestVillageCuisine.add(Expensive.WestVillage.italian); 
WestVillageCuisine.add(Expensive.WestVillage.japanese); 
WestVillageCuisine.add(Expensive.WestVillage.american); 
WestVillageCuisine.add(Expensive.WestVillage.chinese); 
WestVillageCuisine.add(Expensive.WestVillage.spanish); 
WestVillageCuisine.add(Expensive.WestVillage.cafe); 
WestVillageCuisine.add(Expensive.WestVillage.thai); 
WestVillageCuisine.add(Expensive.WestVillage.indian); 
WestVillageCuisine.add(Expensive.WestVillage.viatnamese); 
WestVillageCuisine.add(Expensive.WestVillage.greek); 

System.out.println(getRandom(WestVillageCuisine)); 
System.out.println(WestVillageCuisine.get(0).getrandom()); 

}