從for循環中的if退出for循環？

Question

我得到「的飛行提供匹配信息」 「記錄乘客的詳細信息和預訂完成」

但後來我也越來越「有沒有航班飛往該目的地」

for (int k = 0;k <=4; k++) 
{ 
    if (destination.equalsIgnoreCase(flights[k].getDestination())) 
    { 
     k = 5; 

     System.out.print("\nEnter desired day of departure: "); 
     day = scan.nextLine(); 

     System.out.println("\f"); 

     if (day.equalsIgnoreCase(flights[k].getDay())) 
     { 

      if (flights[k].getBookedSeats() < 100) 
      { 

       passengers[0 + bookedSeats].setName(name); 
       passengers[0 + bookedSeats].setAddress(address); 
       passengers[0 + bookedSeats].setEmail(email); 
       passengers[0 + bookedSeats].setOnFlight(k); 
       flights[k].increaseBookedSeats(); 

       System.out.println("\nA flight is available matching this information"); 
       System.out.println("Passenger's details recorded and booking completed"); 

      }else{ 
       System.out.println("\nThere are no seats available on this flight"); 
      } 
     }else 
     { 
      System.out.println("\nThere are no flights flying to this destination on this day"); 
     } 
    }else if(!destination.equalsIgnoreCase(flights[k].getDestination()) && k==4) 
    { 
     System.out.println("\nThere are no flights flying to this destination"); 
    } 

} 

Answer 1

您可以在if條件中添加break聲明以確保循環中斷。

Answer 2

當循環完成每次迭代運行之前，爲您的乘客找到有效的航班時，會出現此問題。在您的if語句中將k設置爲5是朝正確方向邁出的一步，但不起作用，因爲您在整個塊的其餘部分使用flights[5]。

您可以使用break語句而不是k = 5，但如果你想確保你的代碼將在今後易於維護，您可以通過使用while循環與當你是一個布爾值指定讓你的意圖明確完成。

int k = 0; 
bool done = false; 

while (!done && k <= 4) 
{ 
    if (destination.equalsIgnoreCase(flights[k].getDestination())) 
    { 
     k = 5; 

     System.out.print("\nEnter desired day of departure: "); 
     day = scan.nextLine(); 

     System.out.println("\f"); 

     if (day.equalsIgnoreCase(flights[k].getDay())) 
     { 

      if (flights[k].getBookedSeats() < 100) 
      { 

       passengers[0 + bookedSeats].setName(name); 
       passengers[0 + bookedSeats].setAddress(address); 
       passengers[0 + bookedSeats].setEmail(email); 
       passengers[0 + bookedSeats].setOnFlight(k); 
       flights[k].increaseBookedSeats(); 

       System.out.println("\nA flight is available matching this information"); 
       System.out.println("Passenger's details recorded and booking completed"); 

       // added this line: 
       done = true;   
      }else{ 
       System.out.println("\nThere are no seats available on this flight"); 
      } 
     }else 
     { 
      System.out.println("\nThere are no flights flying to this destination on this day"); 
     } 
    }else if(!destination.equalsIgnoreCase(flights[k].getDestination()) && k==4) 
    { 
     System.out.println("\nThere are no flights flying to this destination"); 
    } 

    k++; 
} 

有些人認爲使用break是好的，而且在許多情況下，我同意他們的觀點;但是，當您回過頭來查看您的代碼（或其他人）時，很高興知道for循環將絕對執行它指定的次數，但while循環可能會提早退出。這隻會讓事情變得更容易。