如何讓程序重新啓動後不正確的輸入java

我想在某個時候重新啓動程序，如果輸入了錯誤的電子郵件地址，用戶將不必完全重新啓動程序，以防他們拼寫錯誤，並且didn沒有注意到。這是我迄今爲止如何讓程序重新啓動後不正確的輸入java

public static void main(String[] args) { 
    String grade = JOptionPane.showInputDialog(null, "Please Specify Your Grade"); 
    String First_name = JOptionPane.showInputDialog(null, "What is your First Name?"); 
    String Last_name = JOptionPane.showInputDialog(null, "What is your Last Name?"); 
    String message = "You are a " + grade + "\n" 
      + "Your Name is " + First_name + " " + Last_name; 
    JOptionPane.showMessageDialog (null, message); 
    String email = JOptionPane.showInputDialog (null, "enter email"); 
     if (email.contains("@branfordschools.org")){     
      JOptionPane.showMessageDialog(null,"Password Accepted"); 
     } else { 
      JOptionPane.showMessageDialog(null,"Password Incorrect, Program Closing"); 
      System.exit(0); 
     }

鑑於Java沒有GOTO（要去使用它，直到它引起的問題，程序是隻爲一個畢業演講）我將如何去使它回去這裏？

String email = JOptionPane.showInputDialog (null, "enter email"); 
     if (email.contains("@branfordschools.org")){     
      JOptionPane.showMessageDialog(null,"Password Accepted"); 
     } else { 
      JOptionPane.showMessageDialog(null,"Password Incorrect, Program Closing"); 
      System.exit(0);

來源

2016-11-16 Brian Coppola

使用do-雖然loop.Google it.Basic東西。 – Inconnu

您正在尋找的概念被稱爲**循環**。換句話說：一些內置的替代gotos。例如，請參閱http://stackoverflow.com/questions/10834202/do-while-syntax-for-java – GhostCat

您可能需要endsWith（）而不是contains。因爲您當前的代碼邏輯會使green @ brandfordschool.orgRANDOMSTUFF無任何問題。 – DejaVuSansMono

下面是一個簡單的while循環，將繼續要求電郵，直到它包含「@ branfordschools.org」

String email; 
    Boolean validEmail = False; 

    while(!validEmail) 
    { 
     //ask the user for the email 
     email = JOptionPane.showInputDialog (null, "enter email"); 
     if (email.contains("@branfordschools.org")){     
      JOptionPane.showMessageDialog(null,"Password Accepted"); 
      validEmail = True; 
     } else { 
      JOptionPane.showMessageDialog(null,"Password Incorrect, Please Re-Enter Password"); 
     } 
    }

來源

2016-11-16 19:21:10

這應該工作;

boolean validInput = false; 
    while (!validInput) { 
     String email = JOptionPane.showInputDialog(null, "enter email"); 
     if (email.contains("@branfordschools.org")) { 
      validInput = true; 
      JOptionPane.showMessageDialog(null, "Password Accepted"); 
     } else { 
      JOptionPane.showMessageDialog(null, "Password Incorrect, Program Closing"); 
     } 
    }

來源

2016-11-16 19:18:45 Ayodeji

如何讓程序重新啓動後不正確的輸入java

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