如何从另一个面板更改卡片布局面板? [英] How to change card layout panels from another panel?

问题描述

我在谷歌上搜索了很多，没有找到解决方案.我想应该会有java高手帮我...

I Googled for a lot, and no solutions found. I think there shall be java masters to help me out ...

这是我的初始化方法:

private void initialize() {
    this.setSize(750, 480);
    this.setContentPane(getJContentPane());
    this.setTitle("Registration");
    JPanel topPane = new TopPane();
    this.getContentPane().add(topPane,BorderLayout.PAGE_START);
    cards=new JPanel(new CardLayout());
    cards.add(step0(),"step0");
    cards.add(step1(),"step1");
    cards.add(step2(),"step2");
    this.getContentPane().add(cards,BorderLayout.CENTER);
}

public JPanel step2(){
    EnumMap<DPFPFingerIndex,DPFPTemplate> template = new EnumMap<DPFPFingerIndex, DPFPTemplate>(DPFPFingerIndex.class); 
    JPanel enrol = new Enrollment(template,2);
    return enrol;
}

public JPanel step0(){
    JPanel userAgree = new UserAgreement();
    return userAgree;
}

public JPanel step1(){
    JPanel userInfo = new UserInformation();
    return userInfo;
}

public JPanel getCards(){
    return cards;
}

<小时><小时>

这个，是另一个step0 JPanel的方法:

---

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This, is the method at another step0 JPanel:

jButtonAgree.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent e) {
                Registration reg = new Registration();
                LayoutManager cards = reg.getCards().getLayout();
                ((CardLayout) cards).show(reg.getCards(),"step1");
            }
        });

<小时>

完全没有反应，我尝试重新验证、重新粉刷和其他工作人员...不起作用...任何人都可以在这里找到任何答案！

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No reation at all, i tried revalidate, repaint and other staff... doesn't work ... any one got any soution here!

推荐答案

这一切都是为了向外界公开正确的方法和常量字符串，以允许类自己交换视图.例如，为您的第一个类提供一个名为 cardlayout 的私有 CardLayout 字段和一个名为 card(持卡人 JPanel)的私有 JPanel 字段，以及一些用于将您的卡片 JPanel 添加到卡片容器的公共字符串常量.还给它一个公共方法，比如说 public void swapView(String key) 允许外部类交换卡片......像这样:

It's all about exposing the right methods and constant Strings to the outside world to allow the class to swap views itself. For example, give your first class a private CardLayout field called cardlayout and a private JPanel field called cards (the card holder JPanel), and some public String constants that are used to add your card JPanels to the cards container. Also give it a public method, say called public void swapView(String key) that allows outside classes to swap cards... something like so:

// code corrected
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class Registration extends JPanel {
   // use these same constants as button texts later
   private static final Dimension PREF_SIZE = new Dimension(450, 300);
   public static final String USER_AGREEMENT = "User Agreement";
   public static final String USER_INFO = "User Information";
   public static final String ENROLLMENT = "Enrollment";
   // we'll extract them from this array
   public static final String[] KEY_TEXTS = {USER_AGREEMENT, USER_INFO, ENROLLMENT};
   private CardLayout cardlayout = new CardLayout();
   private JPanel cards = new JPanel(cardlayout);

   public Registration() {
      cards.add(createUserAgreePanel(), USER_AGREEMENT);
      cards.add(createUserInfoPanel(), USER_INFO);
      cards.add(createEnrollmentPanel(), ENROLLMENT);
      setLayout(new BorderLayout());
      add(cards, BorderLayout.CENTER);
   }

   @Override
   public Dimension getPreferredSize() {
      return PREF_SIZE;
   }

   private JPanel createEnrollmentPanel() {
      JPanel enrol = new JPanel();
      enrol.add(new JLabel("Enrollment"));
      return enrol;
   }

   private JPanel createUserAgreePanel() {
      JPanel userAgree = new JPanel();
      userAgree.add(new JLabel("User Agreement"));
      return userAgree;
   }

   private JPanel createUserInfoPanel() {
      JPanel userInfo = new JPanel();
      userInfo.add(new JLabel("User Information"));
      return userInfo;
   }

   public void swapView(String key) {
      cardlayout.show(cards, key);
   }

}

然后外部类可以简单地通过调用此类的可视化实例上的 swapView 来交换视图，传入适当的键字符串，例如在这种情况下 CardTest.USER_INFO 以显示用户信息 JPanel.

Then an outside class can swap views simply by calling the swapView on the visualized instance of this class, passing in the appropriate key String such as in this case CardTest.USER_INFO to show the user info JPanel.

现在你对这段代码有问题，我用注释指出:

Now you have a problem with this bit of code where I indicate by comment:

    jButtonAgree.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent e) {
            Registration reg = new Registration(); // **** HERE *****
            LayoutManager cards = reg.getCards().getLayout();
            ((CardLayout) cards).show(reg.getCards(),"step1");
        }
    });

在那一行中，您正在创建一个新的 Registration 对象，该对象可能与 GUI 上可视化的对象完全无关，因此在此新对象上调用方法对当前查看的 gui 绝对没有影响.您需要获取对所查看的 Registration 对象的引用，也许通过为此类提供一个 getRegistration 方法，然后调用其方法，如下所示:

On that line you're creating a new Registration object, probably one that is completely unrelated to the one that is visualized on the GUI, and so calling methods on this new object will have absolutely no effect on the currently viewed gui. YOu need instead to get a reference to the viewed Registration object, perhaps by giving this class a getRegistration method, and then call its methods, like so:

class OutsideClass {
   private Registration registration;
   private JButton jButtonAgree = new JButton("Agree");

   public OutsideClass() {
      jButtonAgree.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent e) {
            // make sure registration reference has been obtained first!
            if (registration != null) { 
               registration.swapView(Registration.USER_AGREEMENT);
            }
         }
      });
   }

   // here I allow the calling class to pass a reference to the visualized
   // Registration instance.
   public void setRegistration(Registration registration) {
      this.registration = registration;
   }
}

例如:

@SuppressWarnings("serial")
class ButtonPanel extends JPanel {
   private Registration registration;

   public ButtonPanel() {
      setLayout(new GridLayout(1, 0, 10, 0));
      // go through String array making buttons
      for (final String keyText : Registration.KEY_TEXTS) {
         JButton btn = new JButton(keyText);
         btn.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
               if (registration != null) {
                  registration.swapView(keyText);
               }
            }
         });
         add(btn);
      }
   }

   public void setRegistration(Registration registration) {
      this.registration = registration;
   }
}

以及驱动这一切的 MainClass

and the MainClass that drives this all

class MainClass extends JPanel {
   public MainClass() {
      Registration registration = new Registration();
      ButtonPanel buttonPanel = new ButtonPanel();
      buttonPanel.setRegistration(registration);

      buttonPanel.setBorder(BorderFactory.createTitledBorder("Button Panel"));
      registration.setBorder(BorderFactory.createTitledBorder("Registration Panel"));

      setLayout(new BorderLayout());
      add(registration, BorderLayout.CENTER);
      add(buttonPanel, BorderLayout.SOUTH);
   }

   private static void createAndShowUI() {
      JFrame frame = new JFrame("Registration");
      frame.getContentPane().add(new MainClass());
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.pack();
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);
   }

   public static void main(String[] args) {
      java.awt.EventQueue.invokeLater(new Runnable() {
         public void run() {
            createAndShowUI();
         }
      });
   }
}

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