SWT issue with styledtext

Question

I'm using SWT to create the menu of an application.

In the class "B" the method createContents() is the responsible of create the content of the form:

protected void createContents() {
    shell = new Shell();
    shell.setSize(500, 315);
    shell.setText("SWT Application");

    Label lblNewLabel = new Label(shell, SWT.NONE);
    lblNewLabel.setFont(SWTResourceManager.getFont("Segoe UI", 14, SWT.NORMAL));
    lblNewLabel.setBounds(188, 0, 108, 25);

    Button btnLogs = new Button(shell, SWT.NONE);
    btnLogs.addSelectionListener(new SelectionAdapter() {
        @Override
        public void widgetSelected(SelectionEvent e) {
            Window3 window = new Window3();
            window.open();
        }
    });
    btnLogs.setBounds(386, 242, 75, 25);

    StyledText styledText = new StyledText(shell, SWT.BORDER | SWT.V_SCROLL | SWT.H_SCROLL | SWT.MULTI);
    styledText.setBounds(10, 64, 357, 203);

    Label lblRealTimeLogs = new Label(shell, SWT.NONE);
    lblRealTimeLogs.setBounds(10, 35, 108, 15);

    Button btnFilters = new Button(shell, SWT.NONE);
    btnFilters.addSelectionListener(new SelectionAdapter() {
        @Override
        public void widgetSelected(SelectionEvent e) {
                Window2 window = new Window2();
                window.open();

        }
    });
    btnFilters.setBounds(386, 204, 75, 25);
    btnFilters.setText("FILTRES");

    Label lblConfiguration = new Label(shell, SWT.NONE);
    lblConfiguration.setFont(SWTResourceManager.getFont("Segoe UI", 9, SWT.BOLD));
    lblConfiguration.setText("Configuraci\u00F3");
    lblConfiguration.setBounds(386, 128, 88, 15);

    Button btnNewButton = new Button(shell, SWT.NONE);
    btnNewButton.addSelectionListener(new SelectionAdapter() {
        @Override
        public void widgetSelected(SelectionEvent e) {
            Window4 window = new Window4();
            window.open();
        }
    });
    btnNewButton.setBounds(386, 165, 75, 25);


}   

Then I execute the application and the form in the class "B" is displayed. The problem is that I need to add new lines of text to the styledtext from another class. What I need to do is that in class "A" it checks the content of a file, and if the content has changed it adds the new lines to the styledtext created in the class "B" inside the method createContents()... It seems easy but I'm not able to reference the styledtext created in the class "B" from the class "A" to add these new lines...

Sorry if it's not very clear, my english is not very good...

Any help would be much appreciated. Thanks.

Answer 1

Ok, I've put together a simple example that should show you how it can be done. It basically creates two classes, A and B, where A contains a Text that is modified from B:

public static void main(final String[] args)
{
    Display display = new Display();
    Shell shell = new Shell(display);
    shell.setText("StackOverflow");
    shell.setLayout(new GridLayout(1, false));

    /* Create your gui class */
    A.getInstance(shell);

    shell.pack();
    shell.open();

    /* Wait one second, then simulate generation of other class that calls gui class */
    Display.getDefault().timerExec(1000, new Runnable()
    {
        @Override
        public void run()
        {
            new B();
        }
    });

    while (!shell.isDisposed())
    {
        if (!display.readAndDispatch())
        {
            display.sleep();
        }
    }
    display.dispose();
}

private static class A
{
    private static A    INSTANCE;

    /* This is the field of A we want to modify */
    private Text        text;

    public static A getInstance(Shell shell)
    {
        if (INSTANCE == null && shell != null)
            INSTANCE = new A(shell);

        return INSTANCE;
    }

    private A(Shell shell)
    {
        text = new Text(shell, SWT.BORDER);
    }

    /* This is the method that allows editing the field of A from the outside */
    public void setText(String text)
    {
        if (this.text != null)
            this.text.setText(text);
    }
}

private static class B
{
    public B()
    {
        /* Set the text within A */
        A.getInstance(null).setText("Hello");
    }
}

---

Alternatively, you could make the Text static an forget about the instance stuff.