製作選項>保留<使用布爾值？

Question

好吧，我得到我的程序「完成」，直到我無法解決這個簡單的問題。

我得到這個：

package hotel; 
import java.util.Scanner; 
/** 
* 
* @author Defalt 
*/ 
public class Hotel { 

/** 
* @param args the command line arguments 
*/ 
public static void main(String[] args) { 
    Prices prices = new Prices(); 
    Scanner user_in = new Scanner(System.in); 
    String method; 
    boolean taken = false; 
    boolean taken2 = false; 
    boolean taken3 = false; 
    boolean again = true; 

    //***********Introduction to the hotel************* 

    System.out.println("Welcome to Hotel Vermond's Heaven!"); 
    System.out.println("We are happy to see that you would like to stay with us."); 

    //***********Creating of a Loop************* 


    do { 
    System.out.println("Please, type which room you would like to book: "); 
    System.out.println("Single Bed, Double Bed, President Suit"); 
    method = user_in.nextLine(); 

    //***********Choices of Rooms and Question to book another one************* 

    if ("Single Bed".equals(method)) { 
      System.out.println(prices.describe1()); 
    if ("y".equals(user_in.nextLine())){ 
     if(taken=true){ 
       System.out.println("We are sorry, this room is already booked. Please choose another one"); 
      }else again=true; 
    } else again=true; 
     } else if ("Double Bed".equals(method)){ 
      System.out.println(prices.describe2()); 
    if ("y".equals(user_in.nextLine())){ 
      taken2 = true; 
      again=true; 
     } else again=true; 
    } else if ("President Suit".equals(method)){ 
      System.out.println(prices.describe3()); 
    if ("y".equals(user_in.nextLine())){ 
      taken3 = true; 
      again=true; 
    } else again=true; 

    } else { 
      System.out.println("Please choose one of the rooms above."); 
    } 
      System.out.println("Would you like to book another Room(y/n)\n"); 

    //***********Outbreak if User declines another booking************* 
    //***********Otherwise redo the whole process************* 

    if ("y".equals(user_in.nextLine())){ 
     again=true; 
    } else{ 
     break; 
    } 
}while(again); 
    System.out.println("Thank you and goodbye!"); 

    } 
} 

和我的其他類是這樣的：

package hotel; 
import java.util.Scanner; 
/** 
* 
* @author Defalt 
*/ 
public class Prices { 
Scanner user_in = new Scanner(System.in); 
int price1 = 300; 
int price2 = 800; 
int price3 = 2500; 

//***********Information of the Room including Validation Question************* 

public String describe1() { 
     return 
     "You Choose the Single Bed.\n\tThis room Contains 1 Bed, 1 Fridge a Bathroom but no View on the Ocean.\n\tThis room will cost CHF " + price1 + ".-.\n\tWould you like to book this room?(y/n)"; 
    } 
public String describe2() { 
    return 
    "You Choose the Double Bed.\n\tThis room Contains 1 Queen-size Bed, 1 Fridge a bathroom, an Icemaker but no View on the Ocean.\n\tThis room will cost CHF " + price2 + ".-.\n\tWould you like to book this room?(y/n)"; 
    } 
public String describe3() { 
    return 
    "You Choose the President Suit.\n\tThis room Contains 1 King-size Bed, 1 Fridge, XXL Bathroom, Private Entertainment-System, 65inch Flatscreen and a Balcony with View on the Ocean.\n\tThis room will cost CHF " + price3 + ".-.\n\tWould you like to book this room?(y/n)"; 
    } 
} 

正如你可以看到我試圖使Single Bed保留房間已被服用後。然而，即使在第一次預訂時也會顯示System.out.println("We are sorry, this room is already booked. Please choose another one");。

爲什麼會發生這種情況，儘管我的taken布爾值的初始值爲false？ 還有什麼其他選擇可以讓我的想法發揮作用？

PS !:我想我第一次得到它，但它保持了正確的值，無論我關閉程序並重新啓動它。 （只是一個側面說明）

Answer 1

您需要更改

if(taken=true){ 
      System.out.println("We are sorry, this room is already booked. Please choose another one"); 

到

if(taken==true){ 
      System.out.println("We are sorry, this room is already booked. Please choose another one"); 

注意雙等號的，如果條件。這將檢查taken的值，而不是總是將其設置爲true，這正是目前發生的情況。

另外，由於taken已經是一個布爾值，可以將其簡化爲這樣：

if(taken){ 
      System.out.println("We are sorry, this room is already booked. Please choose another one"); 

這可能會幫助您捕捉這些問題，如果你固定的格式和縮進。我傾向於避免隨時忽略大括號。這通常是Java標準格式：

if(condition) { 
    if(condition) { 
     // do the thing 
    } 
    else { 
     // do the other thing 
    } 
} 
else if(condition) { 
    // do another thing 
} 
else { 
    // do the third thing 
} 

注意如何IFS /其他IFS /別人的同一嵌套級別也保持在相同的縮進層次。這對保持直線有很大的幫助。

編輯：

我想指出的另一件事是，你有again布爾，但你不使用它。如果用戶完成，則不要使用break循環，而應使用again布爾值，並將其設置爲false。這會導致循環條件失敗並很好地退出循環。使用休息是醜陋的。