Java Swing 计时器窗口不会填充

Question

大家。我有4节课； FrameViewerOne 是我运行应用程序的地方，FrameBuilderOne 包含大部分代码，包括二分搜索和许多其他内容，Person 类实现比较，我用compareTo() 方法覆盖它，而我的 TimerLockout 类是我切换到的窗口，该窗口应该填充，将用户锁定 15 秒，并在计时器滴答时显示倒计时。这应该是在用户 3 次错误尝试后发生的。当计时器达到 0 秒时，我希望它关闭 TimerLockout 类并重新打开(setVisible)原始框架。不幸的是，我的代码可以编译，但无法填充计时器。感谢您的宝贵时间，我们将不胜感激任何帮助/建议!

以下是说明: 1) 使用“计数器”允许用户尝试失败 3 次。 2) 如果用户连续三次未能输入正确信息，则系统将锁定15秒。 2.1) 您应该仅以秒为单位显示倒计时窗口，而不是整个系统时间。

//FRAMEVIEWERONE CLASS
import javax.swing.JFrame;//The Frame class is part of the javax.swing package.Swing is the nickname for the gui onterface library in java.
import java.io.*;
public class FrameViewerOne
{
   public static void main(String[] args)throws IOException{//This is a warning to the compiler that we are throwing an exception! Proper syntax is to have this AFTER the method header.
   {
      JFrame Frame1 = new FrameBuilderOne();
      Frame1.setVisible(true);
      Frame1.setSize(200,300);
      Frame1.setTitle("Lab One GUI");
      Frame1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);//This adds the x button on the top right. If you omit this step, the program will keep running even after you close the frame.
   }
  }
}

//FRAMEBUILDERONE CLASS
import javax.swing.*;//The asterik(*) tells Java to import everything that is being used in the package.
import java.awt.event.*;//Has the ActionEvent and KeyEvent. awt: Abstract Window Toolkit
import java.awt.event.ActionListener;
import java.util.*;//This does not have an asterik because I am only importing a specific tool (Scanner) from the java package,util. Scanner is the namespace of the package
import java.io.*; //Always use IOException when working with files. FileNotFoundException is a specific IO Exception. Exceptions are objects.
import javax.swing.BoxLayout;
import javax.swing.JPasswordField;
import javax.swing.border.EtchedBorder;
import javax.swing.border.TitledBorder;

public class FrameBuilderOne extends JFrame{
  private JButton loginBtn, exitBtn;
  private JPanel newPanel, userNamePanel, passWordPanel, studentIdPanel, buttonPanel;
  private JTextField usernameTextField;
  private JPasswordField passwordTextField;
  private JTextField studentIdTextField;
  private JLabel usernameLabel, passwordLabel, studentIdLabel;
  ArrayList<Person> personAry;
  private int attempts;

  public FrameBuilderOne()//Constructor
  {
    createPanel();//Method Call
    personAry = checkInfo(new File("USERDATA.txt"));
    Collections.sort(personAry);
  } 

  private void createPanel()//Actual Method being called
  {
    newPanel = new JPanel();//The reserve word, new, denotes that a constructor method is being called
    newPanel.setBorder(new EtchedBorder());
    newPanel.setBorder(new TitledBorder(new EtchedBorder()));
    newPanel.setLayout(new BoxLayout(newPanel, BoxLayout.Y_AXIS));

    userNamePanel = new JPanel();
    usernameLabel = new JLabel("Username:");
    userNamePanel.add(usernameLabel);

    usernameTextField = new JTextField(10);
    userNamePanel.add(usernameTextField);

    newPanel.add(userNamePanel);

    passWordPanel = new JPanel();
    passwordLabel = new JLabel("Password:");
    passWordPanel.add(passwordLabel);

    passwordTextField = new JPasswordField(10);
    passWordPanel.add(passwordTextField);

    newPanel.add(passWordPanel);
    passwordTextField.setEchoChar('*');

    studentIdPanel = new JPanel();
    studentIdLabel = new JLabel("Student ID:");
    studentIdPanel.add(studentIdLabel);
    studentIdTextField = new JTextField(10);
    studentIdPanel.add(studentIdTextField);

    newPanel.add(studentIdPanel);

    buttonPanel = new JPanel();
    loginBtn = new JButton("Login");
    buttonPanel.add(loginBtn);

    exitBtn = new JButton("Exit");
    buttonPanel.add(exitBtn);

    newPanel.add(buttonPanel);

    ActionListener LoginListener = new ButtonsListen();//Create One Method since since both login and exit buttons share the same/similar task. 
    loginBtn.addActionListener(LoginListener);
    exitBtn.addActionListener(LoginListener);

    add(newPanel);
  }

  public ArrayList<Person> checkInfo(File data)
  {
    Scanner userInput;
    ArrayList <Person> loginAry = new ArrayList<Person>();
    try
      {
        userInput = new Scanner(data);//The reason why this isn't System.in is because you aren't taking input from the keyboard. You are scanning the file.
        while (userInput.hasNextLine())
        {
          String finder = userInput.nextLine();
          String [] loginInfo = finder.split(",");//This is a delimeter
          String usernameInfo = loginInfo [0];
          String passwordInfo = loginInfo [1];
          long studentIdInfo = Long.parseLong(loginInfo[2]);

          Person moreInfo = new Person(usernameInfo, passwordInfo, studentIdInfo);
          loginAry.add(moreInfo);
        }
        userInput.close();
    }
    catch (FileNotFoundException e){
    JOptionPane.showMessageDialog(null, "Error" + e.getMessage());
    }
    return loginAry;
  }

  public class Verify
  {
    /** 
     * This method implements the binary search within the personAry which contains the user's attributes.
     * @param Person info - this is the information of the object Person which contains the username, password, and studentID.
     * @return - this method returns true if info within Person is found. This returns it to the other method which displays the appropriate message to the user. 
    */
    public boolean validate(Person info)
    {
      int low = 0;
      int high = personAry.size()-1;
      int mid;
      while(low <= high)
      {
        mid = (low + high) / 2;
        Person middlePerson = personAry.get(mid);
        int position = middlePerson.compareTo(info);
        if(position < 0)
        {
           low = mid + 1; 
        }
        else if(position > 0)
        {
          high = mid - 1;
        }
        else
        {
          return true;
        }
    }
    return false;
  }
 }

  public boolean validatePassword(String passwordSaver)//Check the password minimum, case sensitivity, and number in password 
  {
    int caseCount=0;
    int numCount=0;
    if(passwordSaver.length() < 10)
    {
      JOptionPane.showMessageDialog(null, "Password must have ten characters");
    }
    else if(passwordSaver.length() >= 10)
      for(int i = 0; i < passwordSaver.length(); i++)
      {
        char current = passwordSaver.charAt(i);
        if(Character.isUpperCase(current)) {caseCount++;}
        else if(Character.isDigit(current)){numCount++;}
      }
    if(caseCount == 0)
    {
      JOptionPane.showMessageDialog(null, "Password must have at least one uppercase character");
      return false;
    }
    else if (numCount == 0)
    {
      JOptionPane.showMessageDialog(null, "Password must have at least one uppercase character");
      return false;
    }
    else
    {
      return true;
    }
  }
public void createTimerClass()
{
  this.setVisible(false); 
  TimerLockout Frame2 = new TimerLockout(this);
}

public class ButtonsListen implements ActionListener{
  public void actionPerformed(ActionEvent e){

    if(e.getSource()==loginBtn)
    {
      String username = usernameTextField.getText();
      String id_str = studentIdTextField.getText();
      long number = Long.parseLong(id_str);
      String password;

      char[] passArray = passwordTextField.getPassword();
      password = new String(passArray);//Study this, write it out

      Person txtFieldInfo = new Person(username, password, number);

      Verify verifyLogin = new Verify();

      if (!validatePassword(password))//also tells the user what went wrong
      { 
        attempts++;
        if(attempts == 3)
        {
          createTimerClass();
          attempts = 0;
        }
      }

      if (verifyLogin.validate(txtFieldInfo))
       {
         JOptionPane.showMessageDialog(null, "Login Successful");//JOptionPane is in the swing package. You must include null, before the message you want to display.
       } 

      else
       {
         JOptionPane.showMessageDialog(null,"Invalid Login Information");
       }
    }

    if (e.getSource()==exitBtn)
    {
      JOptionPane.showMessageDialog(null, "Program Shutting Down");
      System.exit(0);
    }
  }
 }
} 

//PERSON CLASS
public class Person implements Comparable <Object>//The Comparable interface automatiically populates an empty CompareTo method behind the scenes. 
{
  private String username;
  private String password;
  private Long StudentID;

  public Person(String User, String Pass, Long ID)
  {
    this.username = User;
    this.password = Pass;
    this.StudentID = ID;
  }
  public int compareTo(Object otherPerson)//Within the CompareTo method, you must pass in an object. This is overriding the empty CompareTo Method.
  {
    Person other = (Person) otherPerson;//You need to cast an object. tempStorage is going to store the username, password, and studentID. 

    if(other.StudentID > this.StudentID)
    {
      return 1;
    }
    else if(other.StudentID < this.StudentID)
    {
      return -1;
    }
    else
    {
      return 0;
    }
  }

  public String getPassword ()
  {
    return this.password;
  }

  public String getUsername()
  {
    return this.username;
  }

  public Long getStudentID()
  {
    return this.StudentID;
  }
}

//TimerLockout Class
import javax.swing.Timer;
import javax.swing.*;
import java.awt.event.*;
import java.awt.event.ActionListener;
public class TimerLockout extends JFrame
{
  private Timer timerLock;
  private final int STARTING_TIME = 15;
  private int currentTime = 15;
  private final int ENDING_TIME = 0;
  private FrameBuilderOne Frame1;
  private JPanel secondPanel;
  private JLabel timerMessage;

  public TimerLockout(FrameBuilderOne previousFrame)
  {
    TimeListener listener = new TimeListener();
    timerLock = new Timer(1000, listener);
    Frame1 = previousFrame;
    createSecondPanel();
  }

  private void createSecondPanel()
  {
    JPanel secondPanel = new JPanel();

    timerMessage = new JLabel("You Are Temporarily Locked Out");
    secondPanel.add(timerMessage);

    ActionListener TimeListener = new TimeListener();
  }

  public class TimeListener implements ActionListener
  {
    public void actionPerformed(ActionEvent t)
    {

      while(currentTime >= STARTING_TIME)
      {
        currentTime--;
      }
      if(ENDING_TIME == 0)
      {
        Frame1.setVisible(true);
        dispose();
      }
    }
  }
}`

Answer 1

Unfortunately, my code compiles but I can't get the timer to populate

你从未真正启动计时器...

public class TimerLockout extends JFrame {
    //...
    public TimerLockout() {
        TimeListener listener = new TimeListener();
        timerLock = new Timer(1000, listener);
        createSecondPanel();
        // This would be helpful
        timerLock.start();
    }

I don't understand why the timer window isn't showing after 3 failed login attempts.

你永远不会让框架可见......

public void createTimerClass() {
    this.setVisible(false);
    TimerLockout Frame2 = new TimerLockout();
    // ??
}

也许像...

TimerLockout Frame2 = new TimerLockout();
Frame2.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
Frame2.pack();
Frame2.setLocationRelativeTo(null);
Frame2.setVisible(true);

But my TimerLock frame is empty/is really, really small (prediction)

这是因为您从未真正将 secondPanel 添加到 TimerLockout

public TimerLockout() {
    TimeListener listener = new TimeListener();
    timerLock = new Timer(1000, listener);
    createSecondPanel();
    add(secondPanel);
    timerLock.start();
}

When TimerLockout throws a NullPointerException?! (prediction)

这是因为您在 createSecondPanel 中隐藏了 secondPanel，因此当您将其添加到框架时，实例字段为 null。 ..

private void createSecondPanel() {
    // Well, there's your problem?!
    //JPanel secondPanel = new JPanel();
    secondPanel = new JPanel();

    timerMessage = new JLabel("You Are Temporarily Locked Out");
    secondPanel.add(timerMessage);
}

My TimerLockout window closes after 1 second?! (prediction)

这是因为您的TimeListener中的逻辑是错误的

public class TimeListener implements ActionListener {

    public void actionPerformed(ActionEvent t) {

        System.out.println(">> currentTime = " + currentTime + "; STARTING_TIME = " + STARTING_TIME);
        while (currentTime >= STARTING_TIME) {
            currentTime--;
        }
        System.out.println("<< currentTime = " + currentTime + "; STARTING_TIME = " + STARTING_TIME);
        if (ENDING_TIME == 0) {
            dispose();
        }
    }
}

让我们做一些基准测试

+--------+---------------+-------------+-------------+
| loop   | STARTING_TIME | currentTime | ENDING_TIME |
+--------+---------------+-------------+-------------+
| <init> | 15            | 15          | 0           |
+--------+---------------+-------------+-------------+
| 1      | 15            | 15          | 0           |
+--------+---------------+-------------+-------------+
| 2      | 15            | 14          | 0           |
+--------+---------------+-------------+-------------+
| 3      | 15            | 14          | 0           |
+--------+---------------+-------------+-------------+

等等，什么？为什么currentTime更新时间更长？因为一旦 currentTime 不再是 >= STARTING_TIME，它就永远不会递减......此外，第一次 Timer 调用 ActionListener，您将处理该帧(不停止 Timer)，因为 ENDING_TIME 始终为 0 >

相反，它应该更像......

public class TimeListener implements ActionListener {

    public void actionPerformed(ActionEvent t) {
        currentTime--;
        if (currentTime <= ENDING_TIME) {
            dispose();
            timer.stop();
        }
    }
}

一个更简单的解决方案是简单地为 TimerLockOut 类使用 modal JDialog 而不是 JFrame，这意味着您不再需要调整主窗口的可见性状态，因为该对话框将阻止您与子窗口交互，直到它被处理为止

另一个选择是使用 JLayer/JXLayer API 并生成“锁定”效果，for example和 example或者您可以设置一个使用鼠标事件的glassPane，for example