用戶名檢查錯誤

Question

有人可以告訴我這有什麼問題嗎？我有一種感覺，j++不能增加，因此離開j在0，但我不知道。

我在大約2分鐘內就使用了這個課程。它有什麼問題？這是我的代碼：

public static String[] names = { "a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z" }; 
//A to Z 
public static String[] check = { "a","zz" };//Purposely errors a and z, runs the whole check to make sure it works 

public static void usernameCheck() { 
    int errorCount = 0; 
    for(int i = 0; i < check.length;) { 
     for(int j = 0; j < names.length; j++) { 
      if(check[i].toLowerCase().equals(names[j].toLowerCase())) { 
       System.out.println("Username " + check[i] + " is already in use"); 
       System.out.println(i + " and " + j);//Just a check if i or j is increasing at all 
       errorCount++; 
      } 
      if(j == names.length) { 
       System.out.println("Moving to next username"); 
       j = 0; 
       i++; 
      } 
     } 

    } 
    if(errorCount > 0) { 
     System.out.println(errorCount + " Errors Occured"); 
     System.out.println("Please consider revising usernames and try again."); 
    }else 
     System.out.println("Run Successful, no errors have occured."); 
} 

public static void main (String[] args) { 
    usernameCheck(); 
} 

Answer 1

你j變量，如果j達到names.length，將不執行其下for循環迭代;當j爲names.length - 1時，將會發生最後的for循環迭代，因此您的i++將永遠不會執行，並且您的ifor循環是無限循環。

有沒有必要檢查j == names.length。只是讓上i的增量循環增量i：

for(int i = 0; i < check.length; i++) { 

併爲i每個循環中，j for循環將初始化j到0。如果需要，可以將"Moving to next username"打印語句移至j for循環結束之後，但在for循環的i結束之前。