Java Array.Length不正確

Question

我剛剛開始了一個戰爭紙牌遊戲。我製作了一個套牌，然後需要重新洗牌。無論如何，我將需要.length以後纔是正確的。所以當我用這個長度的時候，當我計算的時候它應該是52，所以它得到了160的答案。這是代碼。

import java.util.List; 

public class wargame { 
    public static void main(String args[]){ 
     funtionsforwargame funtionsforwargame=new funtionsforwargame(); 
     funtionsforwargame.instructions(); 
     List<String> randomized_deck=funtionsforwargame.get_deck(); 
     String[] deck_convert = randomized_deck.toArray(new String[0]); 
     String deck=java.util.Arrays.toString(deck_convert); 
     System.out.println(deck); 
     System.out.println(deck.length()); 

    } 

} 

此外，get_deck方法創建一個甲板，作爲數組，然後轉換爲一個列表字符串，並因爲它需要進行改組返回它。所以我接下來返回列表並將其轉換回數組，然後確保它給我的套牌，而不是像ghty @ 67843那樣的東西。所以如果有人知道它爲什麼給我160而不是52，那會很有幫助。如果你不相信列表/數組中有52個，那麼這裏是get_deck方法。

public class funtionsforwargame { 
    public void instructions(){ 
     System.out.println("Welcome to War!"); 
     System.out.println("The object of the game is to collect all cards from the other person."); 
     System.out.println("Basically, all you do is watch and press any key to go to the next round."); 
     System.out.println("Good luck!!!"); 
    } 
    public List<String> get_deck(){ 
     String new_deck[]={"A","A","A","A","2","2","2","2","3","3","3","3","4","4","4","4","5","5","5","5","6","6","6","6","7","7","7","7","8","8","8","8","9","9","9","9","10","10","10","10","J","J","J","J","Q","Q","Q","Q","K","K","K","K"}; 
     List<String> list_convert = Arrays.asList(new_deck); 
     Collections.shuffle(list_convert); 
     return list_convert; 
    } 

} 

在此先感謝。

Answer 1

你知道：

int[] x = {1,2,3}; 

和

String y = Arrays.toString(x); 

是完全不同的東西？

當你做

System.out.println(deck); 
System.out.println(deck.length()); 

長度計數的逗號，空格和[]，這些爲什麼會是一樣的52張牌你在randomized_deck有

你不斯內德使用在所有的陣列中，yyour情況下，列表比正常更多...

只是做

List<String> randomized_deck = funtionsforwargame.get_deck(); 

System.out.println(randomized_deck); 

，並分割你可以使用List#subList(....);

Answer 2

當你這樣做：

String deck=java.util.Arrays.toString(deck_convert); 

數量52成爲160因爲卡10是2數字。您應該打印String[] deck_convert而不是使用Arrays.toString(deck_convert)。

public class wargame { 
    public static void main(String args[]) { 
     funtionsforwargame funtionsforwargame = new funtionsforwargame(); 
     funtionsforwargame.instructions(); 
     List<String> randomized_deck = funtionsforwargame.get_deck(); 
     String[] deck_convert = randomized_deck.toArray(new String[0]); 
     for(String card : deck_convert) 
      System.out.print(card + ","); 
     System.out.println(deck_convert.length); 
    } 
} 

Answer 3

這是真實的，你可以在這個地方檢查：

public class wargame { 

    public static void main(String args[]) { 
     funtionsforwargame funtionsforwargame = new funtionsforwargame(); 
     funtionsforwargame.instructions(); 
     List<String> randomized_deck = funtionsforwargame.get_deck(); 
     String[] deck_convert = randomized_deck.toArray(new String[0]); 
     String deck = java.util.Arrays.toString(deck_convert); 
     System.out.println(deck_convert.length); 
     System.out.println(deck); 
     System.out.println(deck.length()); 

    } 

} 

OUTPUT：

52 
[10, 2, 8, 3, A, 7, 2, 6, 8, 6, 4, K, 3, 9, 10, 3, 5, J, Q, 7, 5, 8, K, J, J, 3, A, 7, 7, 9, 2, 6, K, 4, Q, 9, A, Q, 10, A, 9, 5, K, Q, 5, 6, 8, 10, J, 4, 4, 2] 
160 

在第一種情況下length給你的元素的數量陣列。在另一箇中，您將擁有已轉換字符串的實際長度。 我們可以通過簡單的檢查：

public static void main(String args[]) { 
    funtionsforwargame funtionsforwargame = new funtionsforwargame(); 
    funtionsforwargame.instructions(); 
    List<String> randomized_deck = funtionsforwargame.get_deck(); 
    String[] deck_convert = randomized_deck.toArray(new String[0]); 
    String deck = java.util.Arrays.toString(deck_convert); 
    System.out.println(deck_convert.length); 
    System.out.println(deck); 
    System.out.println(deck.charAt(4)); // here we take one symbol 
    System.out.println(deck.length()); 

} 

OUTPUT：

52 
[A, 7, 2, A, 2, 2, 5, A, 3, 8, 6, Q, 10, 4, K, 4, J, 3, 5, 7, 8, Q, 7, 5, 10, K, 10, 4, 9, 6, Q, 8, K, 7, 6, 9, J, J, 10, K, 5, 2, 8, 6, J, Q, 3, 4, 9, A, 3, 9] 
7 
160 

正如我們所看到的命令System.out.println(deck.charAt(4));給我們**7**。