This is a very bare-bones example that demonstrates how to put an SWT Browser view into a Swing JFrame. Note that you need to download the SWT toolkit and put it in your classpath of your Java project for this to work.

gistfile1.java

import java.awt.Canvas;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JTextField;
import org.eclipse.swt.SWT;
import org.eclipse.swt.awt.SWT_AWT;
import org.eclipse.swt.browser.Browser;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;

public class MySWTBrowserTest {

    static Display display;

    public static void main(String args[]) {
        display = new Display();
        JFrame f = new JFrame("SWT Browser");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        final Canvas canvas = new Canvas();
        f.setSize(650, 550);
        f.getContentPane().add(canvas);
        f.setVisible(true);
        display.asyncExec(new Runnable() {
            @Override
            public void run() {
                Shell shell = SWT_AWT.new_Shell(display, canvas);
                shell.setSize(600, 500);
                Browser browser = new Browser(shell, SWT.NONE);
                browser.setLayoutData(new GridData(GridData.FILL_BOTH));
                browser.setSize(600, 500);
                browser.setUrl("http://leafletplayback.theoutpost.io");
                shell.open();
            }
        });
        while (true) {
            if (!display.readAndDispatch()) {
                display.sleep();
            }
        }
    }
}