Standard Colors

import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.util.ArrayList;
import java.util.List;
import javax.swing.GroupLayout;
import javax.swing.JFrame;
import static javax.swing.JFrame.EXIT_ON_CLOSE;
import javax.swing.JLabel;
import javax.swing.JPanel;

class MyLabel extends JLabel {

    public MyLabel() {
        super("", null, LEADING);
    }

    @Override
    public boolean isOpaque() {
        return true;
    }
}

public class StandardColoursEx extends JFrame {

    public StandardColoursEx() {

        initUI();
    }

    private void initUI() {

        Color[] stdCols = {Color.black, Color.blue, Color.cyan,
            Color.darkGray, Color.gray, Color.green, Color.lightGray,
            Color.magenta, Color.orange, Color.pink, Color.red,
            Color.white, Color.yellow};

        List<JLabel> labels = new ArrayList();

        for (Color col : stdCols) {

            JLabel lbl = createColouredLabel(col);
            labels.add(lbl);
        }

        createLayout(labels.toArray(new JLabel[labels.size()]));

        setTitle("Standard colours");
        setLocationRelativeTo(null);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
    }

    public JLabel createColouredLabel(Color col) {

        MyLabel lbl = new MyLabel();
        lbl.setMinimumSize(new Dimension(90, 40));
        lbl.setBackground(col);

        return lbl;
    }

    private void createLayout(JLabel[] labels) {

        JPanel pane = (JPanel) getContentPane();
        GroupLayout gl = new GroupLayout(pane);
        pane.setLayout(gl);

        pane.setToolTipText("Content pane");

        gl.setAutoCreateContainerGaps(true);
        gl.setAutoCreateGaps(true);

        gl.setHorizontalGroup(gl.createParallelGroup()
                .addGroup(gl.createSequentialGroup()
                        .addComponent(labels[0])
                        .addComponent(labels[1])
                        .addComponent(labels[2])
                        .addComponent(labels[3]))
                .addGroup(gl.createSequentialGroup()
                        .addComponent(labels[4])
                        .addComponent(labels[5])
                        .addComponent(labels[6])
                        .addComponent(labels[7]))
                .addGroup(gl.createSequentialGroup()
                        .addComponent(labels[8])
                        .addComponent(labels[9])
                        .addComponent(labels[10])
                        .addComponent(labels[11]))
                .addComponent(labels[12])
        );

        gl.setVerticalGroup(gl.createSequentialGroup()
                .addGroup(gl.createParallelGroup()
                        .addComponent(labels[0])
                        .addComponent(labels[1])
                        .addComponent(labels[2])
                        .addComponent(labels[3]))
                .addGroup(gl.createParallelGroup()
                        .addComponent(labels[4])
                        .addComponent(labels[5])
                        .addComponent(labels[6])
                        .addComponent(labels[7]))
                .addGroup(gl.createParallelGroup()
                        .addComponent(labels[8])
                        .addComponent(labels[9])
                        .addComponent(labels[10])
                        .addComponent(labels[11]))
                .addComponent(labels[12])
        );

        pack();
    }

    public static void main(String[] args) {

        EventQueue.invokeLater(() -> {
            StandardColoursEx ex = new StandardColoursEx();
            ex.setVisible(true);
        });
    }
}