pon el codigo para ver si podemos ayudar en algo..
con esto arranco el programa import java.awt.Dimension;
import java.awt.Toolkit;
import javax.swing.JFrame;
import javax.swing.UIManager;
public class aplicacion {
public aplicacion() {
JFrame frame = new ventana();
Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
Dimension frameSize = frame.getSize();
if (frameSize.height > screenSize.height) {
frameSize.height = screenSize.height;
}
if (frameSize.width > screenSize.width) {
frameSize.width = screenSize.width;
}
frame.setLocation( ( screenSize.width - frameSize.width ) / 2, ( screenSize.height - frameSize.height ) / 2 );
frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
frame.setVisible(true);
}
public static void main(String[] args) {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (Exception e) {
e.printStackTrace();
}
new aplicacion();
}
}
esta es mi ventana import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import javax.swing.JFrame;
import javax.swing.JPanel;
import oracle.jdeveloper.layout.XYLayout;
public class ventana extends JFrame {
private BorderLayout borderLayout1 = new BorderLayout();
private JPanel jPanel1 = new JPanel();
private XYLayout xYLayout1 = new XYLayout();
public ventana() {
try {
jbInit();
} catch (Exception e) {
e.printStackTrace();
}
}
private void jbInit() throws Exception {
this.getContentPane().setLayout(borderLayout1);
this.setSize( new Dimension(400, 300) );
jPanel1.setLayout(xYLayout1);
jPanel1.setBackground(Color.red);
xYLayout1.setWidth(140);
this.getContentPane().add(jPanel1, BorderLayout.EAST);
}
}