ActionListener 逻辑错误 (Java)

Question

我的 updateButtonResults 按钮有一个小问题。我有 JOptionPane 消息对话框，当用户更新 First Name、Last Name、E-mail 和注册日期 四个字段时，它们会弹出。我的问题是弹出所有 4 条消息，即使我只更新一个字段。示例：我更新了客户的姓氏，消息对话框将按此顺序弹出（名字、姓氏、电子邮件、注册日期）。

这是我的代码

//method for buttons on 'resultFrame'
public void BtnAction3() 
{                        
  updateButtonResults.addActionListener(
        new ActionListener()
        {
           //method for events that will be performed when updateButton is pressed
           public void actionPerformed(ActionEvent e) 
           {
              //instanciates variables to text in textfields
              String fname = fNameTextBoxResults.getText();
              String lname = lNameTextBoxResults.getText();
              String email = eMailTextBoxResults.getText();
              String signUpDate = signUpTextBoxResults.getText();

              try
              {
                 //statement that checks to make sure user enters only letters
                 if(fname.matches("[a-zA-Z]+"))
                 {
                    //updates 'Fname' field in db to text that user inputted in 'fname' textfield
                    rs2.updateString("Fname", fname);
                    JOptionPane.showMessageDialog(null, "Customer first name been updated!");
                 }

                 //statement that prompts user if they enter something other letters
                 else
                 {
                    JOptionPane.showMessageDialog(null, "Please enter first name in correct format!");
                    fNameTextBoxResults.setText("");
                 }

                 //statement that checks to make sure user enters only letters
                 if(lname.matches("[a-zA-Z]+"))
                 {   
                    //updates 'Lname' field in db to text that user inputted in 'lname' textfield                      
                    rs2.updateString("Lname", lname);
                    JOptionPane.showMessageDialog(null, "Customer last name been updated!");
                 }

                 //statement that prompts user if they enter something other letters
                 else
                 {
                    JOptionPane.showMessageDialog(null, "Please enter last name in correct format!");
                    lNameTextBoxResults.setText("");
                 }

                 //statement and actions if user enters a '.'
                 if(email.contains("."))
                 {  
                    //gets last period in "email"
                    int emailDotCheck = email.lastIndexOf(".");

                    //substring to period in variable "emailDotCheck"
                    String extensionCheck = email.substring(emailDotCheck);

                    //statement and actions if user doesn't enter email correctly           
                    if(!email.contains("@") || !extensionCheck.matches("\\.[a-z]{3}"))
                    {
                       JOptionPane.showMessageDialog(null, "Please enter email in correct format!");
                       eMailTextBoxResults.setText("");
                    }                   

                    //statement and actions if user enters email correctly
                    else
                    {
                       //updates 'E-mail' field in db to text that user inputted in 'email' textfield
                       rs2.updateString("E_mail", email);
                       JOptionPane.showMessageDialog(null, "Customer E-mail been updated!");
                    }
                 }

                 //action if user doesnt enter email correctly
                 else
                 {
                    JOptionPane.showMessageDialog(null, "Please enter email in correct format!");
                    eMailTextBoxResults.setText("");
                 }

                 //instance variables for 'signUpDate'
                 int month = 100;
                 int day = 100;
                 int year = 10000;

                 if(signUpDate.matches("\\d{2}/\\d{2}/\\d{4}"))
                 {
                    //instance variables
                    String monthStr = signUpDate.substring(0,2);
                    String dayStr = signUpDate.substring(3,5);
                    String yearStr = signUpDate.substring(6);

                    //parsing intstance variables to Integers
                    month = Integer.parseInt(monthStr);
                    day = Integer.parseInt(dayStr);
                    year = Integer.parseInt(yearStr);

                    //statement and actions if user doesn't follow correct format
                    if(month > 12 || day > 31 || year > 2100)
                    {
                       JOptionPane.showMessageDialog(null, "Please enter date in correct format! (dd/MM/yyyy)");
                       signUpTextBoxResults.setText("");
                    }

                    //statements and actions if user enters date correctly
                    else
                    {
                       //updates 'Sign-up date' field in db to text that user inputted in 'signUpDate' textfield
                       rs2.updateString("Sign_up_date", signUpDate);
                       JOptionPane.showMessageDialog(null, "Customer Sign-up date been updated!");
                    } 
                 }

                 //statement and actions if user doesn't follow correct format           
                 else 
                 {
                    JOptionPane.showMessageDialog(null, "Please enter date in correct format! (dd/MM/yyyy)");
                    signUpTextBoxResults.setText("");
                 }

                 //updates row in db
                 rs2.updateRow();
                 //JOptionPane.showMessageDialog(null, "Customer has been updated!");

              }

              catch(Exception ex)
              {

              }          
           }          
        });

我正在尝试学习浏览我的代码，我已经调试过它，但仍然无法找出逻辑错误。

感谢您的帮助

Answer 1

您有四个文本字段：

fNameTextBoxResults
lNameTextBoxResults
eMailTextBoxResults
signUpTextBoxResults

与其尝试一次验证所有输入，不如尝试使这段代码更模块化。分离与特定字段有关的所有逻辑并将其作为ActionListener 添加到该字段。示例：

 fNameTextBoxResults.addActionListener(
    new ActionListener()
    {
       public void actionPerformed(ActionEvent e) 
       {
             //statement that checks to make sure user enters only letters
             if(fname.matches("[a-zA-Z]+"))
             {
                //updates 'Fname' field in db to text that user inputted in 'fname' textfield
                rs2.updateString("Fname", fname);
                JOptionPane.showMessageDialog(null, "Customer first name been updated!");
             }

             //statement that prompts user if they enter something other letters
             else
             {
                JOptionPane.showMessageDialog(null, "Please enter first name in correct format!");
                fNameTextBoxResults.setText("");
             }
       }
    });

冲洗并重复其他三个字段。如果您需要一些最终类型的操作，那么您可以使用updateButtonResults 执行此操作。否则，按钮就完全没有必要了。

Answer 2

您可能不想使用扩展ActionListener 的匿名类，而是定义一个扩展它的命名类，并定义一个构造函数，您可以通过该构造函数传递数据，例如文本字段的先前值：

class MyActionListener extends ActionListener {  // lousy name, but ...
    public MyActionListener(String prevFirstName, String prevLastName, String prevEMail, String prevSignUp) {
        this.prevFirstName = prevFirstName; ... and so on
    }
    public void ActionPerformed(ActionEvent e) {
        ... what you already have, except that you can say things like
        if (!fname.equals(prevFirstName)) {
            ... now you can do your dialog and it won't show up unless the names
            ... are different
        }
        ...
    }
}

然后这样设置：

public void BtnAction3() 
{                        
  updateButtonResults.addActionListener(
        new MyActionListener(firstName, lastName, eMail, signUp));
}