JButton button1 = new JButton(\"Button 1\");
JButton button2 = new JButton(\"Button 2\");
JFrame frame = new JFrame();
frame.getContentPane().setLayout(new BorderLayout(         
        
You might want to consider using BoxLayout's horizontalGlue:
import java.awt.BorderLayout;
import javax.swing.Box;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class ButtonsLeftAndRight {
    private JFrame frame;
    private JPanel pane;
    private JButton button1;
    private JButton button2;
    public static void main(String[] args) {
        SwingUtilities.invokeLater(new ButtonsLeftAndRight()::createAndShowGui);
    }
    public void createAndShowGui() {
        frame = new JFrame(getClass().getSimpleName());
        pane = new JPanel();
        pane.setLayout(new BoxLayout(pane, BoxLayout.LINE_AXIS));
        button1 = new JButton("Button1");
        button2 = new JButton("Button2");
        pane.add(button1);
        pane.add(Box.createHorizontalGlue());
        pane.add(button2);
        frame.add(pane, BorderLayout.SOUTH);
        frame.pack();
        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
}
This might get you this, before and after resizing: