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Bryan Romero
Asked: 2020-09-18 03:12:17 +0800 CST 2020-09-18 03:12:17 +0800 CST

Using multiple 'if - else' or 'switch' in a method

  • 772

I have created a method in Java that allows me to "check" several JTextFields, the idea is that a user enters his personal data (name, surname, email, password etc)

and that this method allows me to check if JTextfieldsthey are not NULL, the format of the Email is correct and finally that the password is not NULL.

public boolean checkRegistrationData(ArrayList<JTextField> jTxts, JPasswordField pass, JTextField theEmail) {

    if (isJtextNotNull(jTxts) && isJPasswordNotNull(pass) && isValidEmailAddress(theEmail)) {
        JOptionPane.showMessageDialog(null, "A confirmation Code has been sent to your Email adress");
        return true;

    } else if (isJtextNotNull(jTxts) && !isJPasswordNotNull(pass) && isValidEmailAddress(theEmail)) {
        JOptionPane.showMessageDialog(null, "The password field is empty");
        return false;

    } else if (isJtextNotNull(jTxts) && isJPasswordNotNull(pass) && !isValidEmailAddress(theEmail)) {
        JOptionPane.showMessageDialog(null, "The email address is not valid");
        return false;
    }

    else {

        JOptionPane.showMessageDialog(null, "Some data is empty");
        return false;
    }
}

it ArrayList<JTextField> jTxtsis where most of the JTextFields with the user data are "stored".

Is there any way to improve this method ? would it be better to use switch?

java

3 Answers

  1. To avoid showing a message for each type of error, which could be cumbersome for the user, you can group all the errors with the help of a list. That is:

    ✍ Code

    public boolean checkRegistrationData(ArrayList<JTextField> jTxts, JPasswordField pass, JTextField theEmail) {
    List<String> errors = new ArrayList<>();
    if (!isJtextNotNull(jTxts)) {
        errors.add("Some data is empty");
    }
    if (!isJPasswordNotNull(pass)) {
        errors.add("The password field is empty");
    }
    if (!isValidEmailAddress(theEmail)) {
        errors.add("The email address is not valid");
    }
    if (errors.isEmpty()) {
        JOptionPane.showMessageDialog(null, "A confirmation Code has been sent to your Email adress");
    } else {
        JOptionPane.showMessageDialog(null, String.join("\n", errors));
    }
    return errors.isEmpty();
}

    ✍ Exit

    capture

    In this way, you show all the errors that exist in the data entered and the user has the opportunity to correct them all at once.

    • 4
  2. Best Answer

    A common pattern ( Guard clause / Early exit ) is to check at the beginning of the method that the arguments are valid, exiting the method if they are not. In this way, the true objective of the method is separated from the previous verifications. With that pattern, the method would look like this:

    public boolean checkRegistrationData(ArrayList<JTextField> jTxts, JPasswordField pass, JTextField theEmail) {

    if (!isJtextNotNull(jTxts)) {
        JOptionPane.showMessageDialog(null, "Some data is empty");
        return false;
    }

    if (!isJPasswordNotNull(pass)) {
        JOptionPane.showMessageDialog(null, "The password field is empty");
        return false;
    }

    if (!isValidEmailAddress(theEmail)) {
        JOptionPane.showMessageDialog(null, "The email address is not valid");
        return false;
    }

    JOptionPane.showMessageDialog(null, "A confirmation Code has been sent to your Email adress");
    return true;
}
    • 2

  3. switchIt would be useful to evaluate the different results of the same expression. A switch is always more efficient than a concatenation of if, elseif...else. But in your case you evaluate 4 different expressions:

    1. isJtextNotNull(jTxts) && isJPasswordNotNull(pass) && isValidEmailAddress(theEmail)
    2. isJtextNotNull(jTxts) && !isJPasswordNotNull(pass) && isValidEmailAddress(theEmail)
    3. isJtextNotNull(jTxts) && isJPasswordNotNull(pass) && !isValidEmailAddress(theEmail)
    4. If neither expression is true

    I don't see much point in using switch in this case unless you use an extra variable, for example form_state , and its value corresponds to each of the possible states of the form.

    • 1