java - 为什么我的 ActionListener 不起作用？

Question

我正在创建一个简单的应用程序来编码文本，但我正在努力处理一些 ActionListeners。当我从 JComboBox 中选择某些内容时，一定会发生一些事情(如果您选择 Caesar's Cipher，则必须出现偏移量，如果您选择 Beaufort，则偏移量将消失；偏移量是 JTextField)，并且根据选择执行按钮将得到相应的 ActionListener 实现。问题是，当我选择 Caesar's Cipher 时，什么也没有发生，即使我添加实现 ActionListener 的 CaesarsCipher 来编码文本，也不会起作用。

MyFrame.java

package cipher;

import java.awt.BorderLayout;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;

@SuppressWarnings("serial")
class MyFrame extends JFrame {

    private JButton executeButton;
    private ComboBoxPanel leftPanel;
    private TextPanel rightPanel;

    public MyFrame(String title) {

        super(title);

        //Initiate the frame
        initFrame();
        //Initiate the button that need to be pressed to execute a cipher
        initButton();

        //Init the panels
        initPanel();

        //Pack everything together;
        packing();

        //Make the frame visible to the user
        setVisible(true);
    }

    //////////PACKING EVERYTHING TOGETHER//////////

    private void packing() {

        add(executeButton,BorderLayout.SOUTH);
        add(leftPanel, BorderLayout.WEST);
        add(rightPanel, BorderLayout.EAST);

    }

    //////////INITIATING THE FRAME WITH ALL COMPONENTS//////////

    private void initPanel() {

        leftPanel = new ComboBoxPanel();
        rightPanel = new TextPanel();

    }

    private void initButton() {

        executeButton = new JButton("Execute cipher");

    }


    private void initFrame() {

        setSize(800,400);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLocationRelativeTo(null);
        setLayout(new BorderLayout());
        setResizable(false);

    }

    //////////HIDE THE OFFSET WHEN CHOOSING ALGORITHMS THAT DO NOT REQUIRE OFFSET//////////

    public void hideOffset() {
        leftPanel.hideOffset();
    }

    public void showOffset() {
        leftPanel.showOffset();
    }


    //////////UPDATE LEFT PANEL AFTER HIDING OFFSET//////////
    public void updateLeftPanel() {
        leftPanel.updatePanel();
    }

    //////////LISTENERS//////////

    /////COMBO BOX/////

    public void addComboBoxListener(ActionListener comboBoxListener) {
        leftPanel.addComboBoxListener(comboBoxListener);
    }

    /////EXECUTE BUTTON/////

    public void addExecuteButtonListener(ActionListener executeButtonListener) {
        executeButton.addActionListener(executeButtonListener);
    }

    //////////GETTERS//////////

    /////OFFSET GETTER/////
    public Integer getOffset() {
        return Integer.parseInt(leftPanel.getOffset());
    }

    /////INPUT GETTER/////

    public String getInputText() {
        return rightPanel.getInputText();
    }


    //////////SETTERS//////////

    /////OUTPUT TEXT SETTER/////
    public void setOutputText(String text) {
        rightPanel.setOutputText(text);
    }

}

ComboBoxPanel.java

package cipher;

import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionListener;

import javax.swing.BorderFactory;
import javax.swing.JComboBox;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.border.Border;

@SuppressWarnings("serial")
class ComboBoxPanel extends JPanel {

    private final String []CIPHERS = {"Caesar's Cipher", "ROT13", "Beaufort Cipher", "Autokey Cipher"};
    @SuppressWarnings("rawtypes")
    private JComboBox comboCiphers;

    private JTextField offset;

    public ComboBoxPanel() {

        initSize();
        initComboBox();
        initBorder();
        initLayout();
        initTextField();

        packing();

    }


    private void initTextField() {

        offset = new JTextField(10);

    }

    private void initLayout() {

        setLayout(new GridBagLayout());

    }

    private void packing() {
        GridBagConstraints gbc = new GridBagConstraints();
        gbc.gridx = 0;
        gbc.gridy = 0;
        gbc.ipadx = 10;
        add(comboCiphers,gbc);
        gbc.gridy = 1;
        add(offset,gbc);

    }

    private void initBorder() {

        Border outer = BorderFactory.createEmptyBorder(5, 5, 5, 5);
        Border inner = BorderFactory.createTitledBorder("Choose the cipher");
        setBorder(BorderFactory.createCompoundBorder(outer, inner));

    }

    @SuppressWarnings({ "unchecked", "rawtypes" })
    private void initComboBox() {

        comboCiphers = new JComboBox(CIPHERS);

    }

    //Remainder: delete this, let the layout to do its job.
    private void initSize() {
        Dimension size = getPreferredSize();
        size.width = 390;
        setPreferredSize(size);

    }

    public void hideOffset() {
        offset.setVisible(false);
    }

    public void showOffset() {
        offset.setVisible(true);
    }

    public void updatePanel() {
        revalidate();
        repaint();
    }

    public void addComboBoxListener(ActionListener comboBoxListener) {
        comboCiphers.addActionListener(comboBoxListener);
    }

    public String getOffset() {
        return offset.toString();
    }

}

TextPanel.java

package cipher;

import java.awt.Color;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionListener;

import javax.swing.BorderFactory;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.border.Border;
import javax.swing.border.LineBorder;

@SuppressWarnings("serial")
class TextPanel extends JPanel {

    private JTextArea inputArea, outputArea;
    private JScrollPane inputScroll, outputScroll;

    public TextPanel() {

        //////////PANEL METHODS///////

        /*
        //Initiate the size of the panel
        initSize();
        */

        //Initiate the border of the entire panel
        initBorder();
        //Setup the layout of the panel
        initLayout();

        //////////TEXT AREAS METHODS///////
        //Initiate the text areas
        initTextArea();
        //Initiate the borders for the 2 text areas
        initTextAreaBorder();
        //Create scrolls for both text areas
        initScrollPane();

        //Pack everything together
        packing();

    }

    private void packing() {

        GridBagConstraints gbc = new GridBagConstraints();
        gbc.gridx = 0;
        gbc.gridy = 0;
        gbc.weightx = 1;
        gbc.weighty = 1;
        gbc.fill = GridBagConstraints.BOTH;
        add(inputScroll,gbc);
        gbc.gridx = 0;
        gbc.gridy = 1;
        gbc.weightx = 1;
        gbc.weighty = 1;
        add(outputScroll,gbc);

    }

    private void initScrollPane() {

        inputScroll = new JScrollPane(inputArea);
        outputScroll = new JScrollPane(outputArea);

    }

    private void initTextAreaBorder() {

        inputArea.setBorder(new LineBorder(Color.black));
        outputArea.setBorder(new LineBorder(Color.black));

    }

    private void initBorder() {

        Border outer = BorderFactory.createEmptyBorder(5, 5, 5, 5);
        Border inner = BorderFactory.createTitledBorder("Text");
        setBorder(BorderFactory.createCompoundBorder(outer,inner));

    }

    private void initLayout() {

        setLayout(new GridBagLayout());

    }

    private void initTextArea() {
        inputArea = new JTextArea(10,77);

        outputArea = new JTextArea(10,77);
        outputArea.append("Output...");
        outputArea.setEditable(false);

    }

    public void addComboBoxListener(ActionListener comboBoxListener) {
        //.addActionListener(comboBoxListener);
    }

    /*private void initSize() {

        //setPreferredSize sets the minimum
        Dimension size = getPreferredSize();
        size.width = 390;
        setPreferredSize(size);

    }*/

    public String getInputText() {
        return inputArea.toString();
    }

    public void setOutputText(String text) {
        outputArea.append(text);
    }

}

ApplicationController.java

package cipher;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JComboBox;

public class ApplicationController{

    private MyFrame frame;

    public ApplicationController(MyFrame frame) {

        this.frame = frame;
        this.frame.addComboBoxListener(new ComboBoxListener());

    }

     class ComboBoxListener implements ActionListener {

            @SuppressWarnings("rawtypes")
            @Override
            public void actionPerformed(ActionEvent e) {

                JComboBox c = (JComboBox) e.getSource();
                String selected = c.getSelectedItem().toString();

                if(selected.equalsIgnoreCase("Caesar's Cipher")) {
                    frame.addExecuteButtonListener(new CaesarsCipher());
                    frame.showOffset();
                    frame.updateLeftPanel();
                } else if(selected.equalsIgnoreCase("ROT13")) {
                    frame.showOffset();
                    frame.updateLeftPanel();
                } else if(selected.equalsIgnoreCase("Beaufort Cipher")) {
                    frame.hideOffset();
                    frame.updateLeftPanel();
                } else if(selected.equalsIgnoreCase("Autokey Cipher")) {
                    frame.hideOffset();
                    frame.updateLeftPanel();
                }

            }

        }

     class CaesarsCipher implements ActionListener {

         public void actionPerformed(ActionEvent e) {

             int offset = frame.getOffset();
             char []text = frame.getInputText().toCharArray();

             for(int i = 0 ; i < text.length ; i++) {
                 text[i] = (char)(((int)text[i] + offset) % 26);
             }

             String newText = new String(text);
             frame.setOutputText(newText);

         }

     }

}

请有人解释一下出了什么问题。我准备好从错误中吸取教训。谢谢。

Answer 1

您没有创建 applicationController 的实例，因此您的组合框监听器从未创建。

将来，您不应该扩展 JFrame。您所需要的只是它的一个实例。通过放入这些额外的添加监听器方法，您还增加了复杂性。