檢查電子郵件地址是否有效。有效的電子郵件地址應(yīng)同時(shí)包含 at 符號(hào) (@) 或點(diǎn) (.)。如果用戶省略了其中任何一個(gè)，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(xù)重復(fù)此步驟，直到用戶提供有效的電子郵件地址。當(dāng)用戶輸入有效的電子郵件地址時(shí)，繼續(xù)執(zhí)行程序的其余部分。- 我們應(yīng)該為此使用循環(huán)，但我不確定使用哪個(gè)或如何設(shè)置它。我在考慮使用while循環(huán)？我們不能使用我在這里看到人們使用的正則表達(dá)式方法，因?yàn)槲覀冞€沒有學(xué)到這一點(diǎn)。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(xiàn)1877條經(jīng)驗(yàn) 獲得超1個(gè)贊
我建議使用while循環(huán)。當(dāng)for您知道需要重復(fù)操作多少次時(shí)，循環(huán)是最好的，但while循環(huán)適用于重復(fù)未知次數(shù)。它可以運(yùn)行 0 到多次。
至于您的while循環(huán)條件，您只想檢查電子郵件地址是否無效。因此，請(qǐng)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(xiàn)1735條經(jīng)驗(yàn) 獲得超5個(gè)贊
像這樣的東西應(yīng)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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