Projeto POO + Interface Gráfica

package telas;
        import java.awt.event.ActionEvent;
        import java.awt.event.ActionListener;

import javax.swing.*;
import java.awt.Toolkit;
public class CalculadoraImposto extends JFrame{
	//Declarando os componentes
	public JLabel lblTituloPrograma;
	public JLabel lblValorTotalNota;
	public JLabel lblIrrf;
	public JLabel lblPis;
	public JLabel lblCofins;
	public JLabel lblCsll;
	public JLabel lbltotal;
	public JLabel lblPorcentagem;
	public JButton btnCalcular;

	public JTextField txtValorTotalNota;
	public JTextField txtIrff;
	public JTextField txtPis;
	public JTextField txtCofins;
	public JTextField txtCsll;
	

//construtor 
	public CalculadoraImposto(){
		
		//look and feel pega do OS atual
		try {
        UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
    } 
    catch (Exception e) {
    }
				this.setResizable(false);
				this.setTitle("Calculadora");
				this.setBounds(500,250,300,310);
				this.getContentPane().setLayout(null);
				
				
					
		//label - Titulo do Programa
				lblTituloPrograma = new JLabel();
				lblTituloPrograma.setText("Calculadora de Impostos");
				lblTituloPrograma.setIcon(new javax.swing.ImageIcon(getClass().getResource("/img/calculadora.png")));
				lblTituloPrograma.setBounds(50,2,190,50);
				this.add(lblTituloPrograma);
				
		//label - valor total da nota
				lblValorTotalNota = new JLabel();
				lblValorTotalNota.setText("Valor total da Nota:");
				lblValorTotalNota.setBounds(10,40,108,50);
				this.add(lblValorTotalNota);
		
		//textfield - valor total nota
				txtValorTotalNota = new JTextField();
				txtValorTotalNota.setBounds(110,55,70,20);
		        this.add(txtValorTotalNota);
		
		 //label - porcentagem taxa
				lblPorcentagem = new JLabel();
				lblPorcentagem.setText("Insira a taxa %");
				lblPorcentagem.setBounds(70,75,108,50);
				this.add(lblPorcentagem);
				
		//label - lblIrrf
				lblIrrf = new JLabel();
				lblIrrf.setText("IRRF:");
				lblIrrf.setBounds(40,95,108,50);
				this.add(lblIrrf);
		
		//textfield - irff
				txtIrff = new JTextField();
				txtIrff.setBounds(70,110,70,20);
				this.add(txtIrff);
		
		//label - lblPis
				lblPis = new JLabel();
				lblPis.setText("PIS:");
				lblPis.setBounds(48,125,108,50);
				this.add(lblPis);
		
		//textfield - pis
				txtPis = new JTextField();
				txtPis.setBounds(70,140,70,20);
				this.add(txtPis);
		
		//label - lblCofins
				lblCofins = new JLabel();
				lblCofins.setText("COFINS:");
				lblCofins.setBounds(27,150,108,50);
				this.add(lblCofins);

		//textfield - cofins
				txtCofins = new JTextField();
				txtCofins.setBounds(70,165,70,20);
				this.add(txtCofins);
		
		//label - lblCsll
				lblCsll = new JLabel();
				lblCsll.setText("CSLL:");
				lblCsll.setBounds(42,180,108,50);
				this.add(lblCsll);
				
		//textfield - csll
				txtCsll = new JTextField();
				txtCsll.setBounds(70,195,70,20);
				this.add(txtCsll);
		
		
		
		
		
		//botao calcular
		btnCalcular = new JButton();
		btnCalcular.setText("Calcular");
		btnCalcular.setBounds(100, 240, 90, 25);
		this.add(btnCalcular);
		
		
		//acao do botao calcular
		  btnCalcular.addActionListener(new ActionListener() {
	            public void actionPerformed(ActionEvent evt) {
	            	
	               
	            }
	        });
		  
	}
	
	public static void main(String[] args) {
		CalculadoraImposto exemplo = new CalculadoraImposto();
        exemplo.setVisible(true);
        
   
	}
}