Remove the gap between components in gridBagLayout

Question

This is my class:

public class Main extends JFrame{
private Container container;
private GridBagConstraints cons;
private JPanel panelDisplay;
private int curX = 0, curY = 0;

public Main() {
    initComp();
}

public static void main(String[] args) {

    SwingUtilities.invokeLater(new Runnable() {
        @Override
        public void run() {
            Main ex = new Main();
            ex.setVisible(true);
        }
    });
}

private void initComp()
{
    container = this.getContentPane();
    container.setLayout(new GridBagLayout());
    cons = new GridBagConstraints();

    cons.gridx = 0;
    cons.gridy = 0;
    container.add(new PanelNot(), cons);


    panelDisplay = new JPanel();
    panelDisplay.setBackground(Color.blue);
    panelDisplay.setPreferredSize(new Dimension(600, 400));
    panelDisplay.setLayout(new GridBagLayout());
    cons.gridx = 1;
    cons.gridy = 0;
    container.add(panelDisplay, cons);

    for (int i = 0; i < 15; i++) // display 15 components
    {            
        displayNot(); 
    }    


    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //setting the default close operation of JFrame
    this.pack();        
    this.setResizable(false);
    this.setLocationRelativeTo(null);
    this.setVisible(true);

}

private void displayNot()
{
    setLocGrid();
    panelDisplay.add(new Not1(), cons);
}

private void setLocGrid()
{
    if(curX==11) // maximum component to be display in 1 row is 11
    {
        curY += 1;
        curX = 0;
    }

    cons.gridx = curX;
    cons.gridy = curY;
    cons.anchor = GridBagConstraints.FIRST_LINE_START;
    cons.weightx = 1.0;
    cons.weighty = 1.0;

    curX += 1;
}

}

this is the output:

Just ignore the left panel. My problem is in the right panel which is, there is a gap between one component (component: Not1) to the other. i have set the preferedSize of each component to x=20 and y=30 as you can see in every component's background where the color is gray. So my question is, how to make the gap disappear?

UPDATE : my expectation:

Answer 1

Start by getting rid of cons.weightx and cons.weightx

private void setLocGrid() {
    if (curX == 11) // maximum component to be display in 1 row is 11
    {
        curY += 1;
        curX = 0;
    }

    cons.gridx = curX;
    cons.gridy = curY;
    cons.anchor = GridBagConstraints.FIRST_LINE_START;
    //cons.weightx = 1.0;
    //cons.weighty = 1.0;

    curX += 1;
}

This will get you something like...

Now, you need some kind of filler that can push the components to the top/left position, for example...

for (int i = 0; i < 15; i++) // display 15 components
{
    displayNot();
}

cons.gridy++;
cons.gridx = 12; // Based on you conditions in setLocGrid
cons.weightx = 1;
cons.weighty = 1;
JPanel filler = new JPanel();
filler.setOpaque(false);
panelDisplay.add(filler, cons);

Which will give you something like...