java |我的 Action 监听器没有被调用

Question

我正在使用操作监听器来更改链接到组合框的 JLabel 图标。我让它工作了，但在添加一些代码来打开对话框后，它停止调用操作监听器(不知道它是如何破坏的)。我从保存的备份中再次尝试，但无法使其工作。

目前它加载默认图标，但更改组合框中的值不会像以前那样调用监听器。

这就是我的程序的样子，它应该在此处显示德国国旗: demo_Image

这是我的代码:

package LTranslator;
import java.awt.event.ActionEvent;
import javax.swing.*;

public class LangTranslator extends javax.swing.JFrame {

public LangTranslator() {
    initComponents();
}

/**Calls the action listener*/
public void actionPerformed(ActionEvent e) {
    JComboBox cb = (JComboBox)e.getSource();
    String flagImage = (String)cb.getSelectedItem();
    updateLabel(flagImage);

}

/**Changes the icon */
protected void updateLabel(String name) {
    ImageIcon icon = createImageIcon("/images/" + name + ".png");
    imgOne.setIcon(icon);
    imgOne.setToolTipText("A drawing of a " + name.toLowerCase());
    if (icon != null) {
        imgOne.setText(null);
    } else {
        imgOne.setText("Image not found");
    }
}

/** Returns an ImageIcon, or null if the path was invalid. */
protected static ImageIcon createImageIcon(String path) {
    java.net.URL imgURL = LangTranslator.class.getResource(path);
    if (imgURL != null) {
        return new ImageIcon(imgURL);
    } else {
        System.err.println("Couldn't find file: " + path);
        return null;
    }
}

private void initComponents() {

    comboOne = new javax.swing.JComboBox<>();
    btnGetLanguage = new javax.swing.JButton();
    btnTranslate = new javax.swing.JButton();
    txtGetLanguage = new javax.swing.JTextField();
    cbxOne = new javax.swing.JCheckBox();
    cbxTwo = new javax.swing.JCheckBox();
    cbxThree = new javax.swing.JCheckBox();
    cbxFour = new javax.swing.JCheckBox();
    imgOne = new javax.swing.JLabel();
    jScrollPane1 = new javax.swing.JScrollPane();
    taOne = new javax.swing.JTextArea();

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
    setTitle("Translator");

    comboOne.setModel(new javax.swing.DefaultComboBoxModel<>(new String[] { "Japanese", "Swedish", "German", "Dutch" }));
    comboOne.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            comboOneActionPerformed(evt);
        }
    });

    btnGetLanguage.setText("Get Language");
    btnGetLanguage.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            btnGetLanguageActionPerformed(evt);
        }
    });

    btnTranslate.setText("Translate");
    btnTranslate.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            btnTranslateActionPerformed(evt);
        }
    });

    cbxOne.setText("Hello World");

    cbxTwo.setText("How are you?");

    cbxThree.setText("What day is it today?");

    cbxFour.setText("Goodbye");

    imgOne.setIcon(new javax.swing.ImageIcon(getClass().getResource("/images/Japanese.png"))); // NOI18N

    taOne.setColumns(20);
    taOne.setRows(5);
    taOne.setEnabled(false);
    jScrollPane1.setViewportView(taOne);

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addGap(46, 46, 46)
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(layout.createSequentialGroup()
                    .addComponent(comboOne, javax.swing.GroupLayout.PREFERRED_SIZE, 123, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addGap(35, 35, 35)
                    .addComponent(btnGetLanguage)
                    .addGap(43, 43, 43)
                    .addComponent(txtGetLanguage))
                .addGroup(layout.createSequentialGroup()
                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                        .addComponent(cbxFour)
                        .addGroup(layout.createSequentialGroup()
                            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                                .addComponent(cbxTwo)
                                .addComponent(cbxOne)
                                .addComponent(cbxThree))
                            .addGap(31, 31, 31)
                            .addComponent(btnTranslate, javax.swing.GroupLayout.PREFERRED_SIZE, 86, javax.swing.GroupLayout.PREFERRED_SIZE)))
                    .addGap(18, 18, 18)
                    .addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 243, Short.MAX_VALUE)))
            .addContainerGap())
        .addGroup(layout.createSequentialGroup()
            .addGap(140, 140, 140)
            .addComponent(imgOne)
            .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addGap(35, 35, 35)
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(comboOne, javax.swing.GroupLayout.PREFERRED_SIZE, 30, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addComponent(btnGetLanguage)
                .addComponent(txtGetLanguage, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
            .addComponent(imgOne)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 25, Short.MAX_VALUE)
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                .addGroup(layout.createSequentialGroup()
                    .addComponent(cbxOne)
                    .addGap(18, 18, 18)
                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                        .addComponent(cbxTwo)
                        .addComponent(btnTranslate, javax.swing.GroupLayout.PREFERRED_SIZE, 30, javax.swing.GroupLayout.PREFERRED_SIZE))
                    .addGap(18, 18, 18)
                    .addComponent(cbxThree)
                    .addGap(17, 17, 17)
                    .addComponent(cbxFour))
                .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 152, javax.swing.GroupLayout.PREFERRED_SIZE))
            .addGap(17, 17, 17))
    );

    pack();
}// </editor-fold>

Answer 1

您将一个 ActionListener 添加到调用 comboOneActionPerformed(evt) 的 ComboBox，但触发更改的方法名为 actionPerformed(ActionEvent e)。改变这个，它应该可以工作。我想知道这是否可以编译。您还可以实现 ActionListener，然后添加 ActionListener，如下所示:comboOne.addActionListener(this);