GridBagConstraints.CENTER has the following syntax.
public static final int CENTER
In the following code shows how to use GridBagConstraints.CENTER field.
/*w w w . j a v a 2s .c o m*/ import java.awt.Component; import java.awt.Container; import java.awt.GridBagConstraints; import java.awt.GridBagLayout; import java.awt.Insets; import javax.swing.JButton; import javax.swing.JFrame; public class Main { public static void main(String[] a) { final JFrame frame = new JFrame("GridBagLayout"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setLayout(new GridBagLayout()); JButton button; button = new JButton("One"); addComponent(frame, button, 0, 0, 1, 1, GridBagConstraints.CENTER, GridBagConstraints.NONE); button = new JButton("Two"); addComponent(frame, button, 1, 0, 1, 1, GridBagConstraints.CENTER, GridBagConstraints.NONE); button = new JButton("Three"); addComponent(frame, button, 0, 1, 2, 1, GridBagConstraints.CENTER, GridBagConstraints.NONE); button = new JButton("Four"); addComponent(frame, button, 0, 2, 1, 1, GridBagConstraints.CENTER, GridBagConstraints.NONE); frame.setSize(500, 200); frame.setVisible(true); } private static void addComponent(Container container, Component component, int gridx, int gridy, int gridwidth, int gridheight, int anchor, int fill) { Insets insets = new Insets(0,0,0,0); GridBagConstraints gbc = new GridBagConstraints(gridx, gridy, gridwidth, gridheight, 1.0, 1.0, anchor, fill, insets, 0, 0); container.add(component, gbc); } }