You could add the button to the frame's glass pane. This takes a little bit of work to make happen, as you need to keep track of the scroll pane relative to the glass pane, but it should achieve the desired effect
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class OverlayButton {
public static void main(String[] args) {
new OverlayButton();
}
public OverlayButton() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private JScrollPane sp;
private JButton btn;
private JTextArea ta;
private JPanel glassPane;
public TestPane() {
setLayout(new BorderLayout());
btn = new JButton("Print");
ta = new JTextArea(10, 20);
BufferedReader br = null;
try {
br = new BufferedReader(new FileReader(new File("Script.txt")));
String text = null;
while ((text = br.readLine()) != null) {
ta.append(text + "\n");
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
br.close();
} catch (Exception e) {
}
}
ta.setCaretPosition(0);
sp = new JScrollPane(ta);
glassPane = new JPanel() {
@Override
public void doLayout() {
Point p = sp.getLocation();
Dimension dim = sp.getSize();
p = SwingUtilities.convertPoint(sp, p, this);
btn.setSize(btn.getPreferredSize());
int barWidth = sp.getVerticalScrollBar().getWidth();
int barHeight = sp.getHorizontalScrollBar().getHeight();
int x = p.x + (dim.width - btn.getWidth()) - barWidth;
int y = p.y + (dim.height - btn.getHeight()) - barHeight;
btn.setLocation(x, y);
}
};
glassPane.setOpaque(false);
glassPane.add(btn);
glassPane.addComponentListener(new ComponentAdapter() {
@Override
public void componentResized(ComponentEvent e) {
e.getComponent().doLayout();
}
});
add(sp);
}
@Override
public void addNotify() {
super.addNotify();
SwingUtilities.getRootPane(this).setGlassPane(glassPane);
glassPane.setVisible(true);
glassPane.revalidate();
}
@Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.dispose();
}
}
}
Take a look at How to use Root Panes for more details