java - JCheckBox 自动选择第一个选项

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我正在开发一个系统，一旦选择了 JComboBox 的一个字段， ，更改 JButton 的文本，从连接到离线，具体取决于 JComboBox 中写入的字段的状态。 .

所有这些都已完成，但我有一个问题。

当我运行程序时，系统自动进入事件addActionListener ，并不是说我曾经选择过 JComboBox 的字段？

有人可以帮我吗？

根据答案进行编辑

...下面的代码块被写入在comboBox.addActionListener 之前执行的方法中。编写这段代码是因为我需要动态地填充 JComboBox 的元素...

private void actionOfSearch(){

table.addMouseListener(new MouseAdapter(){

    public void mouseClicked(MouseEvent me){

    if(ipAvailable){
        blockSetRemoteUnit = false;
        timer = new Timer(10000, new ActionListener() {
            public void actionPerformed(ActionEvent e) {
            //extracted_values is a Vector<Stirng>
            if(typeOfConnection.equals("ABC") || typeOfConnection.equals("DEF"))
                extracted_values = new E_ConnectionABC_DEF(resourceSelected, credential).result;
            else{
                try {
                    extracted_values = new E_ConnectionOther(resourceSelected, credential).result;
                } catch (InterruptedException e1) { e1.printStackTrace(); }
            }
            int size = extracted_values.elementAt(0).size();
            String stringOfNameLabel = "";
            String stringValueOfResource = "";
            JLabel nameResource = null;
            JProgressBar progressBar = null;
            subPanelOfinfoServer.removeAll();
            subPanelOfinfoServer.repaint();
            subPanelOfinfoServer.revalidate();
            if(!blockSetRemoteUnit)
                comboBox.addItem(" ");
            for(int i=0;i<size;i++){
                stringOfNameLabel = extracted_values.elementAt(1).elementAt(i);
                //Here I popolate the fields of JComboBox, and how you can see,
                //I can Change the fields, every time that I selected a different Row
                //of the JTable.        
                if(!blockSetRemoteUnit && stringOfNameLabel.length()==2 && stringOfNameLabel.contains(":"))
                    comboBox.addItem(stringOfNameLabel);         
                nameResource = new JLabel(stringOfNameLabel);
                nameResource.setHorizontalAlignment(SwingConstants.CENTER);
                stringValueOfResource = extracted_values.elementAt(0).elementAt(i);
                progressBar = new JProgressBar();
                progressBar.setValue(Integer.parseInt(stringValueOfResource));

                subPanelOfinfoServer.add(nameResource);
                subPanelOfinfoServer.add(progressBar);
            }
            blockSetRemoteUnit = true;
            }
       });
        timer.setRepeats(true);
        timer.setCoalesce(true);
        timer.setInitialDelay(0);
        timer.start();
    }
    else{
        logger.warn("[JTABLE-SelectRow]ATTENTION! " + resourceSelected + " is not Available");
        JOptionPane.showMessageDialog(null, "IP " + resourceSelected + " is not Available");
    }   
    }});
}

现在，在其他 Java 方法中(调用之后)，您会找到以下代码:

private JPanel connectResource(){
    JPanel remoteResource = new JPanel();
    JPanel panelSouth = new JPanel();
    //jstMpd is a Vector<Vector<String>>
    jstMpd  = getAlreadyMapped();
    remoteResource.setLayout(new BorderLayout());

    final JButton ResourceConnect = new JButton();

    comboBox.addActionListener (new ActionListener () {
        public void actionPerformed(ActionEvent e) {
            Object lettereReadComboBox = comboBox.getSelectedItem();
            final String letter = lettereReadComboBox.toString();

            try {
                alreadyMapped = ctrIfalreadyMapped(ResourceSelected, letter, typeOfConnection, jstMpd);
            } catch (IOException e1) {
            } catch (InterruptedException e1) {
            }

            if(alreadyMapped)
                ResourceConnect.setIcon(new ImageIcon(path + "src/img/Disconnect.png"));
            else
                ResourceConnect.setIcon(new ImageIcon(path + "src/img/Drive-Network-Connected.png"));

            ResourceConnect.addActionListener( new ActionListener(){
                public void actionPerformed(ActionEvent ae) {
                    try {
                        alreadyMapped = ctrIfalreadyMapped(ResourceSelected, letter, typeOfConnection, jstMpd);
                    } catch (IOException | InterruptedException e1) {
                    }
                    if(alreadyMapped){
                        try {
                            String localLetterMounted = deleteElement(ResourceSelected, letter, jstMpd);
                            if(localLetterMounted!=""){
                                new E_Mapped_Drives().unmountResource(localLetterMounted);
                                ResourceConnect.setIcon(new ImageIcon(path + "src/img/Drive-Network-Connected.png"));
                                ResourceConnect.setActionCommand("!alreadyMapped");
                            }
                        } catch (IOException e) { 
                            JOptionPane.showMessageDialog(null, "You didn't selected any Letter of Remote Resource!\n Please Re-Try");
                        }
                    }
                    else{
                        String letterGetted = "";
                        String letterMounted= "";
                        if(typeOfConnection.equals("RDP") || typeOfConnection.equals("VNC")){
                            try {
                                letterGetted = letter;
                                letterMounted = new E_Mapped_Drives().mountResourceWindows(ResourceSelected, letterGetted, credential);
                                jstMpd.addElement(new Vector<String>(Arrays.asList(letterGetted, ResourceSelected,typeOfConnection,letterMounted)));
                                ResourceConnect.setIcon(new ImageIcon(path + "src/img/Disconnect.png"));
                            } catch (IOException e) {
                                logger.warn("[BOTTONE-ResourceCONNECT][IOException] You didn't selected any letter!");
                                JOptionPane.showMessageDialog(null, "You didn't selected any Letter of Remote Resource!\n Please Re-Try");
                            }
                        }
                        else{
                            try {
                                letterGetted = new E_Mapped_Drives().mountResourceLinux(ResourceSelected, credential);//, comboBox.getSelectedItem(), credential);
                                ResourceConnect.setIcon(new ImageIcon(path + "src/img/Disconnect.png"));
                            } catch (IOException e) {
                                JOptionPane.showMessageDialog(null, "You didn't selected any Letter of Remote Resource!\n Please Re-Try");
                            }
                        }
                    }
                }
            });
        }
    });

    panelSouth.setBackground(getColorBackground());
    remoteResource.add(comboBox, BorderLayout.NORTH);
    remoteResource.add(ResourceConnect, BorderLayout.CENTER);
    remoteResource.add(panelSouth, BorderLayout.SOUTH);
    return remoteResource;
}

Answer 1

可能您正在创建操作监听器，然后再添加项目执行 JComboBox，或者在注册操作监听器后以编程方式选择组合框的某些值。将所有项目添加到 JComboBox 后创建操作监听器。

发生这种情况是因为如果组合框没有项目，当您添加项目时，它就会成为选定的值，从而触发操作监听器。