Membuat ComboBox Transparan

ClButtonTransparant.java

import java.awt.Color;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.Shape;
import java.awt.geom.RoundRectangle2D;
import javax.swing.*;

@SuppressWarnings("serial")
public class ClButtonTransparant extends JButton{
	  private static final Color TL = new Color(1f,1f,1f,.2f);
	  private static final Color BR = new Color(0f,0f,0f,.4f);
	  private static final Color ST = new Color(1f,1f,1f,.2f);
	  private static final Color SB = new Color(1f,1f,1f,.1f);
	  private Color ssc;
	  private Color bgc;
	  private int r = 8;
	  public ClButtonTransparant(String text) {
	    super(text);
	  }
	  public ClButtonTransparant(String text, Icon icon) {
	    super(text, icon);
	  }
	  @Override public void updateUI() {
	    super.updateUI();
	    setContentAreaFilled(false);
	    setFocusPainted(false);
	    setOpaque(false);
	    setForeground(Color.WHITE);
	  }
	  @Override protected void paintComponent(Graphics g) {
	    int x = 0;
	    int y = 0;
	    int w = getWidth();
	    int h = getHeight();
	    Graphics2D g2 = (Graphics2D)g.create();
	    g2.setRenderingHint(
	      RenderingHints.KEY_ANTIALIASING,
	      RenderingHints.VALUE_ANTIALIAS_ON);
	    Shape area = new RoundRectangle2D.Float(x, y, w-1, h-1, r, r);
	    ssc = TL;
	    bgc = BR;
	    ButtonModel m = getModel();
	    if(m.isPressed()) {
	      ssc = SB;
	      bgc = ST;
	    }else if(m.isRollover()) {
	      ssc = ST;
	      bgc = SB;
	    }
	    g2.setPaint(new GradientPaint(x, y, ssc, x, y+h, bgc, true));
	    g2.fill(area);
	    g2.setPaint(BR);
	    g2.draw(area);
	    g2.dispose();
	    super.paintComponent(g);
	  }
	}

ClPanelTransparant.java

import javax.swing.JPanel;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D; 

@SuppressWarnings("serial")
public class ClPanelTransparant extends JPanel
{
	private Color clr;
	
	public ClPanelTransparant()
	{
		setOpaque(false);
		clr = new Color(getBackground().getRed(), getBackground().getRed(), getBackground().getGreen(),50);
	}	
	
	public void setBackground(Color bg)
	{
		super.setBackground(bg);
		clr = new Color(getBackground().getRed(), getBackground().getRed(), getBackground().getGreen(),50);
		repaint();
	}
	
	protected void paintComponent(Graphics graph)
	{
		super.paintComponent(graph);
		Graphics2D g2d = (Graphics2D) graph.create();
		g2d.setColor(clr);
		g2d.fillRect(0, 0, getWidth(), getHeight());
		g2d.dispose();
	}
	
}

frameTransparanCombo.java

import java.awt.Component;
import java.awt.EventQueue;
import javax.swing.DefaultListCellRenderer;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JComboBox;
import javax.swing.DefaultComboBoxModel;
import javax.swing.JLabel;
import javax.swing.ImageIcon;
import javax.swing.border.TitledBorder;
import java.awt.Color;
import javax.swing.JTextField;
import javax.swing.JButton;
import javax.swing.SwingConstants;
import java.awt.Font;

@SuppressWarnings("serial")
public class frameTransparanCombo extends JFrame {

	private JPanel contentPane;
	@SuppressWarnings("rawtypes")
	private JComboBox cbJenis;
	private JLabel lblWall;
	private JPanel panel;
	private JLabel lblId;
	private JTextField txtID;
	private JTextField txtNama;
	private JLabel lblJenis;
	private JLabel lblModel;
	private JTextField txtModel;
	private JButton btnSimpan;
	private JButton btnUbah;
	private JButton btnHapus;
	private JLabel lblIcon;
	
	/**
	 * Create the frame.
	 */
	@SuppressWarnings({ "rawtypes", "unchecked" })
	public frameTransparanCombo() 
	{
		setTitle("Transparan ComboBox");
		setResizable(false);
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setBounds(100, 100, 602, 404);
		contentPane = new JPanel();
		contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
		setContentPane(contentPane);
		contentPane.setLayout(null);
		
		panel = new ClPanelTransparant();
		panel.setBorder(new TitledBorder(null, "Data Komputer", TitledBorder.RIGHT, TitledBorder.TOP, null, new Color(255, 255, 255)));
		panel.setBounds(29, 12, 414, 238);
		contentPane.add(panel);
		panel.setLayout(null);
		
		lblId = new JLabel("ID : ");
		lblId.setFont(new Font("Comic Sans MS", Font.BOLD, 12));
		lblId.setForeground(new Color(255, 204, 153));
		lblId.setBounds(12, 12, 70, 15);
		panel.add(lblId);
		
		txtID = new JTextField();
		txtID.setBounds(116, 10, 114, 19);
		panel.add(txtID);
		txtID.setColumns(10);
		
		JLabel lblNama = new JLabel("Nama : ");
		lblNama.setFont(new Font("Comic Sans MS", Font.BOLD, 12));
		lblNama.setForeground(new Color(255, 204, 153));
		lblNama.setBounds(12, 50, 70, 15);
		panel.add(lblNama);
		
		txtNama = new JTextField();
		txtNama.setBounds(116, 48, 269, 19);
		panel.add(txtNama);
		txtNama.setColumns(10);
		
		lblJenis = new JLabel("Jenis : ");
		lblJenis.setFont(new Font("Comic Sans MS", Font.BOLD, 12));
		lblJenis.setForeground(new Color(255, 204, 153));
		lblJenis.setBounds(12, 94, 70, 15);
		panel.add(lblJenis);
		
		cbJenis = new JComboBox();
		cbJenis.setBounds(116, 89, 162, 24);
		panel.add(cbJenis);
		cbJenis.setModel(new DefaultComboBoxModel(new String[] {"== Pilih ==", "Motherboard", "Mouse", "Keyboard"}));
		
		cbJenis.setOpaque(false);
		cbJenis.setRenderer(new DefaultListCellRenderer(){
		    @Override
		    public Component getListCellRendererComponent(JList list, Object value, int index, boolean isSelected, boolean cellHasFocus) {
		        JComponent comp = (JComponent)super.getListCellRendererComponent(list, value, index, isSelected, cellHasFocus);
		        comp.setOpaque(false);
		        return comp;
		    }});
		
		lblModel = new JLabel("Model : ");
		lblModel.setFont(new Font("Comic Sans MS", Font.BOLD, 12));
		lblModel.setForeground(new Color(255, 204, 153));
		lblModel.setBounds(12, 141, 70, 15);
		panel.add(lblModel);
		
		txtModel = new JTextField();
		txtModel.setBounds(116, 139, 114, 19);
		panel.add(txtModel);
		txtModel.setColumns(10);
		
		btnSimpan = new ClButtonTransparant("Simpan");
		btnSimpan.setVerticalTextPosition(SwingConstants.BOTTOM);
		btnSimpan.setHorizontalTextPosition(SwingConstants.CENTER);
		btnSimpan.setIcon(new ImageIcon("/home/resa/Aplikasi Java/SwingJava/src/TransparanComboBox/Simpan.png"));
		btnSimpan.setBounds(471, 12, 117, 53);
		contentPane.add(btnSimpan);
		
		btnUbah = new ClButtonTransparant("Ubah");
		btnUbah.setVerticalTextPosition(SwingConstants.BOTTOM);
		btnUbah.setHorizontalTextPosition(SwingConstants.CENTER);
		btnUbah.setIcon(new ImageIcon("/home/resa/Aplikasi Java/SwingJava/src/TransparanComboBox/Ubah.png"));
		btnUbah.setBounds(471, 96, 117, 53);
		contentPane.add(btnUbah);
		
		btnHapus = new ClButtonTransparant("Hapus");
		btnHapus.setVerticalTextPosition(SwingConstants.BOTTOM);
		btnHapus.setHorizontalTextPosition(SwingConstants.CENTER);
		btnHapus.setIcon(new ImageIcon("/home/resa/Aplikasi Java/SwingJava/src/TransparanComboBox/Hapus.png"));
		btnHapus.setBounds(471, 184, 117, 53);
		contentPane.add(btnHapus);
		
		lblIcon = new JLabel("");
		lblIcon.setIcon(new ImageIcon("/home/resa/Aplikasi Java/SwingJava/src/TransparanComboBox/icon.png"));
		lblIcon.setBounds(455, 241, 133, 137);
		contentPane.add(lblIcon);
		
		lblWall = new JLabel("");
		lblWall.setIcon(new ImageIcon("/home/resa/Aplikasi Java/SwingJava/src/TransparanComboBox/wall.jpg"));
		lblWall.setBounds(0, -11, 600, 389);
		contentPane.add(lblWall);
		setLocationRelativeTo(null);
	}
	
	/**
	 * Launch the application.
	 */
	public static void main(String[] args) {
		EventQueue.invokeLater(new Runnable() {
			public void run() {
				try {
					//UIManager.setLookAndFeel("com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel");
					frameTransparanCombo frame = new frameTransparanCombo();
					frame.setVisible(true);
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		});
	}
}