Read data from active window in Java

Question

Is there any way to read data from a program which is developed using SWING. I am able to read Title of the window using Native JNA. I have tried the below code and it is giving me the title of window.

public class JNATest {
    HWND window = null;

    public static void main(String[] args) {
        JNATest jna = new JNATest();
        if(jna.isWindowOpen("Test")){
            jna.activateWindow();
        }
    }

    public void activateWindow() {
        if(window != null) {
            User32.INSTANCE.ShowWindow(window, 9);
            User32.INSTANCE.SetForegroundWindow(window);
        }
    }

    public boolean isWindowOpen(String title) {
        window = null;
        User32.INSTANCE.EnumWindows(new WNDENUMPROC() {

            @Override
            public boolean callback(HWND hWnd, Pointer arg1) {
                if(window == null) {
                    char[] windowText = new char[512];
                    User32.INSTANCE.GetWindowText(hWnd, windowText, 512);
                    String wText = Native.toString(windowText);
                    if (wText.contains(title)) {
                        window = hWnd;
                    }
                    System.out.println(" - Found sub window / control class: " + new String(windowText).trim());
                }
                return true;

            }
        }, null);

        return window != null;
    }