如何跟踪 Java 应用程序中的所有组件？

Question

I'm more interested in understanding how it's done in the real world.

I am building an application in Javafx where it is listening to INPUT within a webpage using webview. When the user clicks an input a new Button("Input Clicked") is created and added to a GridPane, at the bottom. The user can then click the button and a dialog will appear for information, like the inputs ID, Class, Value, etc.

If a webpage has 10+ inputs, how does one keep track of all the new Button()s created? Do I write to a file? Do I create an arraylist? If so, what if the user closes the application? How do I recreate the GridPane, almost like a File->Save feature?

I've attached an image of the application. As you can see, I have clicked the google search INPUT 4 times, 4 buttons were created. Each one needs to be unique. If I close the application, it needs to recreate it.

the code is simply

mainGrid.add(new Button("Input Clicked",IncrementCol,IncrementRow);

Example

Answer 1

One way of keeping track of your input controls is through a pattern called " Model-View-Controller ". The state of the input controls is captured in the Model, which you can persist and then restore later.

Something like this. The UI class combines the View (the JTextField and JLabel , etc.) and the Controller ( ActionListener ). You might want to separate these into different classes in a large enough UI. The Model class holds all the state, that the Controller shifts between the View and the Model .

This allows you to keep track of the things in the UI.

public UI extends JFrame {
    private Model model;
    private JTextField fn;
    private JTextField ln;
    private JLabel n;

    public JFrame(Model model) {
        this.model = model;
        fn = JTextField(model.getFirstName());
        ln = JTextField(model.getLastName());
        n = new JLabel(model.getFullName());
        JButton b = new JButton("Submit");
        JButton s = new JButton("Save");
        JButton r = new JButton("Restore");
        b.setActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent ev) {
                model.setFirstName(fn.getText());
                model.setLastName(ln.getText());
                n.setText(model.getFullName());
            }
        });
        s.setActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent ev) {
                model.save();  
            }
        });
        r.setActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent ev) {
                model.load();  
                fn.setText(model.getFirstName());
                ln.setText(model.getLastName());
                n.setText(model.getFullName());                  
            }
        });
        add(fn);
        add(ln);
        add(l);
        add(b);
        add(s);
        add(r);
    }
}

public class Model {
    private firstName;
    private lastName;
    private fullName;

    public String getFirstName() { return firstName; }
    public void setFirstName(String firstName) { this.firstName; update(); }
    public String getLastName() { return firstName; }
    public void setLastName(String firstName) { this.firstName; update(); }
    public String getFullName() { return fullName; }
    public void update() { this.fullName = firstName + " " + lastName }

    public void save() {
        try(PrintWriter w = new PrintWriter(new FileWriter("c:/temp/test.txt"))) {
           w.println(firstName);
           w.println(lastName);
        }
    }

    public void load() {
       try(Scanner s = new Scanner(new FileReader("c:/temp/test.txt"))) {
          firstName = s.next();
          lastName = s.next();
          update();
       }
    }
}

Answer 2

If your Buttons/GridPane is Serializable, you could choose an also serializable list implementation (like ArrayList) and then serialize that into a file whenever the user adds a button or closes the application. Deserialization then allows for easy reconstruction of the saved state.

Answer 3

Create model objects, like simple JavaBean, to contain the state and data. These objects should not be JavaFC classes, just simple classes you create. You would serialize these to a file as you see fit. I wrote a lot of code for doing this for JavaFX applications and I can attest that it is possible to write to files on a web deployed JavaFX, though there were some hoops to jump.

You can store the saved objects in memory in custom domain specific Context or Manager singletons (eg AccountManager.getInstance() or AccountnContext.getInstance() ). These singleton objects would query for the serialized objects upon startup or on request. You can have a serialization class that manages all the sterilization of objects to disk. Maybe it takes the name of the file and the object type and would either save it or retrieve it. The singletons would hold and provide access to the JavaBean objects.

EDIT: Just to add to @sh0rug0ru's answer, my answer is centered on the Model aspect of the MVC. The Model is responsible for containing the state, values, and sterilization of the domain specific objects.