檢查電子郵件地址是否有效。有效的電子郵件地址應同時包含 at 符號 (@) 或點 (.)。如果用戶省略了其中任何一個，您的程序必須通知用戶提供的電子郵件不正確，并提示用戶重新輸入電子郵件地址。繼續重復此步驟，直到用戶提供有效的電子郵件地址。當用戶輸入有效的電子郵件地址時，繼續執行程序的其余部分。- 我們應該為此使用循環，但我不確定使用哪個或如何設置它。我在考慮使用while循環？我們不能使用我在這里看到人們使用的正則表達式方法，因為我們還沒有學到這一點。This is the code that we have to update(we are now supposed to use a loop to continue asking the user for email address until both characters are used, instead of exiting the program):if(emailAddress.contains("@")){ //prompt user for major & classification code System.out.print("\nPleast enter two characters (Character #1: Major Code and Character #2: Classification Code): "); } else{ //exit program if no '@' symbol in email address System.out.print("\nYou have entered an invalid email address."); System.out.println("\n\nGoodbye!"); System.exit(0);}
2 回答
冉冉說
TA貢獻1877條經驗 獲得超1個贊
我建議使用while循環。當for您知道需要重復操作多少次時，循環是最好的，但while循環適用于重復未知次數。它可以運行 0 到多次。
至于您的while循環條件，您只想檢查電子郵件地址是否無效。因此，請檢查!emailAddress.contains("@")它是否不包含@，!emailAddress.contains(".")如果不包含.。
您可以使用||來查看任一條件是否為真。
// Prompt the user
System.out.println("Please enter an email address");
String emailAddress = // read in their email adress
while(!emailAddress.contains("@") || !emailAddress.contains(".")) {
System.out.println("You have entered an invalid email address, please enter another.");
emailAddress = // read in their email address again
}
// Email address now contains "@" and "."
喵喔喔
TA貢獻1735條經驗 獲得超5個贊
像這樣的東西應該工作：
// While email does not contain the two characters..
// Keep asking the user to enter the correct email.
while(!emailAddress.contains("@") || !emailAddress.contains(".")){
System.out.print("\nYou have entered an invalid email address.");
// Add line of code here to ask for email address.
// Update emailAddress of course
}
//prompt user for major & classification code
System.out.print("\nPleast enter two characters (Character #1: Major Code and Character #2: Classification
// ...
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