Question

我有一个简短的应用程序，我遇到了组合框的问题。应用程序：用户可以从下拉菜单中选择文件夹或创建文件夹（在我的应用程序的主文件夹中）。

我需要什么：用户选择或创建此文件夹后。路径存储在变量中，其余的组合框将显示该新路径中的文件。

我没有使用GUI和Swing，这是我的代码：

public class test {

private JFrame MyFrame;
boolean pathChanged = false;
String xPath = null;

/**
 * Launch the application.
 */
public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                test window = new test();
                window.MyFrame.setVisible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
}

/**
 * Create the application.
 */
public test() {
    initialize();
}


/**
 * Initialize the contents of the frame.
 */
@SuppressWarnings("unchecked")
private void initialize() {
    MyFrame = new JFrame();
    MyFrame.setTitle("My Application");
    MyFrame.setBounds(100, 100, 500, 400);
    MyFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    MyFrame.getContentPane().setLayout(null);

//If it's a directory it will be displayed in the main dropdown menu
File fileBtn1 = new File("C:\\ProgramManagement\\");
    String[] directories = fileBtn1.list(new FilenameFilter() {
        public boolean accept(File current, String name) {
            return new File(current, name).isDirectory();
        }
    });


    JComboBox<Object> comboBox = new JComboBox<Object>(directories);
    comboBox.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {

            //Changes top label to name of the program selected
            lblProgramName.setText((String) comboBox.getSelectedItem()); 
            //Changes path name to the name of the selected program
            xPath = (String) comboBox.getSelectedItem(); 
            pathChanged = true; // Tells comboBoxes the path has changed
            System.out.println(xPath); // Just testing path name

        }
    });
    comboBox.setBounds(315, 47, 150, 25);
    MyFrame.getContentPane().add(comboBox);

//comboBox_1 and comboBox_2 need to update depending on the xPath variable
JComboBox comboBox_1 = new JComboBox<String>();
    comboBox_1.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent arg0) {

        }
    });
    //comboBox_1.setSelectedIndex(0);

    /*
     * Updating first ComboBox
     */
    if(pathChanged){
        System.out.println("PATH HAS CHANGED");
        System.out.println("NEW PATH IS   " + xPath);
        File fileStep1 = new File("C:\\ProgramManagement\\" + xPath + "\\step1");
        String[] directory1 = fileStep1.list(new FilenameFilter() {
            public boolean accept(File current, String name) {
                return new File(current, name).isFile();
            }
        });
        comboBox_1.removeAllItems();
        for (int i=0; i < directory1.length; i++ ){
            String sample = directory1[i];
            comboBox_1.addItem(sample);         
        }
        comboBox_1.setBounds(315, 189, 150, 25);
        MyFrame.getContentPane().add(comboBox_1);
    }else{
        System.out.println("Path NOT changed");
        comboBox_1.setBounds(315, 189, 150, 25);
        MyFrame.getContentPane().add(comboBox_1);
    }

}
}

我试图把相关的代码放在这里。我认为我的问题是，一旦应用程序命中initialize（），就会生成组合框及其内容。我怎么能改变呢？非常感谢！

Answer 1

您应该移动此代码：

 if(pathChanged){
    System.out.println("PATH HAS CHANGED");
    System.out.println("NEW PATH IS   " + xPath);
    File fileStep1 = new File("C:\\ProgramManagement\\" + xPath + "\\step1");
    String[] directory1 = fileStep1.list(new FilenameFilter() {
        public boolean accept(File current, String name) {
            return new File(current, name).isFile();
        }
    });
    comboBox_1.removeAllItems();
    for (int i=0; i < directory1.length; i++ ){
        String sample = directory1[i];
        comboBox_1.addItem(sample);         
    }
    comboBox_1.setBounds(315, 189, 150, 25);
    MyFrame.getContentPane().add(comboBox_1);
}else{
    System.out.println("Path NOT changed");
    comboBox_1.setBounds(315, 189, 150, 25);
    MyFrame.getContentPane().add(comboBox_1);
}

进入这里：

comboBox.addActionListener(new ActionListener() {
    public void actionPerformed(ActionEvent e) {

        //Changes top label to name of the program selected
        lblProgramName.setText((String) comboBox.getSelectedItem()); 
        //Changes path name to the name of the selected program
        xPath = (String) comboBox.getSelectedItem(); 
        pathChanged = true; // Tells comboBoxes the path has changed
        System.out.println(xPath); // Just testing path name
        //////////////////Move code here////////////////////////////////
    }
});

您希望在更改第一个组合框时执行此代码... actionPerformed()

动态更新ComboBox列表

1 个答案: