Calculadora - GUI

panelWest.setLayout(new GridLayout(3, 3));

panelWest = new JPanel( new GridLayout(3,3) );

package swingbasico;

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.UIManager;

public class CalculadoraGUI {
	private JFrame frame;
	private JPanel panelWest, panelCentral, panelNorth, panelEast;
	private JButton[] buttonWest, buttonCenter, buttonEast;
	private JTextField textFieldNorth;

	private void makeGUI() {
		frame = new JFrame("Calculadora");
		panelWest = new JPanel();
		panelCentral = new JPanel();
		panelNorth = new JPanel();
		panelEast = new JPanel();

		buttonWest = new JButton[9];
		buttonCenter = new JButton[4];
		buttonEast = new JButton[1];
		textFieldNorth = new JTextField(10);

		//criar botoes da regiao oeste
		buttonWest[0] = new JButton("7");
		buttonWest[1] = new JButton("8");
		buttonWest[2] = new JButton("9");
		buttonWest[3] = new JButton("4");
		buttonWest[4] = new JButton("5");
		buttonWest[5] = new JButton("6");
		buttonWest[6] = new JButton("1");
		buttonWest[7] = new JButton("2");
		buttonWest[8] = new JButton("3");

		//criar botoes da regiao central
		buttonCenter[0] = new JButton("/");
		buttonCenter[1] = new JButton("*");
		buttonCenter[2] = new JButton("-");
		buttonCenter[3] = new JButton("+");

		//criar botoes da regiao leste
		buttonEast[0] = new JButton("=");


		for (int i=0; i<buttonWest.length; i++) {
			buttonWest[i].setPreferredSize(new Dimension(45, 30)); //defir tamanho dos botoes da painel oeste
			panelWest.add(buttonWest[i]); //adicionar botoes ao painel oeste
		}

		for (int i=0; i<buttonCenter.length; i++) {
			buttonCenter[i].setPreferredSize(new Dimension(50, 30)); //definiar tamahno do botoes do painel central
			panelCentral.add(buttonCenter[i]); //adicionar bootoes ao painel central
		}

		buttonEast[0].setPreferredSize(new Dimension(35, 30));
		panelNorth.add(textFieldNorth); //adicionar campo de texto ao painel norte
		panelEast.add(buttonEast[0]); //adicionar botao ao painel leste

		panelCentral.setLayout(new GridLayout(0,1));
		panelWest.setLayout(new GridLayout(3, 3));
		panelEast.setLayout(new GridLayout(0,1));

		frame.getContentPane().add(BorderLayout.CENTER, panelCentral);
		frame.getContentPane().add(BorderLayout.WEST, panelWest);
		frame.getContentPane().add(BorderLayout.NORTH, panelNorth);
		frame.getContentPane().add(BorderLayout.EAST, panelEast);
		frame.setResizable(false);
		frame.pack();
		frame.setVisible(true);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	}

	public static void main(String[] args) throws ClassNotFoundException {
		try {
			UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
		} catch (Exception e) {
			e.printStackTrace();
		}
		new CalculadoraGUI().makeGUI();
    }
}

public void actionPerformed(ActionEvent e) {
		if (e == buttonWest[0]) {
		
		}
		String texto = buttonWest[0].getText();
		textFieldNorth.setText(texto);
	}

class ButtonListner implements ActionListener {
		public void actionPerformed(ActionEvent e) {
			String texto = buttonWest[0].getText();
			textFieldNorth.setText(texto);
		}
	}

	class ButtonListner1 implements ActionListener {
		public void actionPerformed(ActionEvent e) {
			String texto = buttonCenter[0].getText();
			textFieldNorth.setText(texto);
		}
	}

public void actionPerformed(ActionEvent e) {

		converter(); //Metodo para pegar dados e converter
    	if(e.getSource() == bt_somar || e.getSource() == mi_somar)
		{
			resultado = num1 + num2;
			//tf_resultado.setText(String.valueOf(resultado));			
		}

		if(e.getSource() == bt_subtrair || e.getSource() == mi_subtrair)
		{
			resultado = num1 - num2;			
		}

		if(e.getSource() == bt_multiplicar || e.getSource() == mi_multiplicar)
		{
			resultado = num1 * num2;			
		}

		if(e.getSource() == bt_dividir || e.getSource() == mi_dividir)
		{
			resultado = num1 / num2;			
		}
		
		exibe();	//Método para exibir resultado

		if(e.getSource() == bt_limpar || e.getSource() == mi_limpar)
		{
			tf_num1.setText("");
			tf_num2.setText("");
			tf_resultado.setText("");
			tf_num1.requestFocus();
		}

		if(e.getSource() == bt_sair || e.getSource() == mi_sair)
		{
			System.exit(0);
		}

	}
	public void converter()
	{
		num1 = Double.parseDouble(tf_num1.getText());
		num2 = Double.parseDouble(tf_num2.getText());
	}
	
	public void exibe()
	{
		tf_resultado.setText(""+calculo.format(resultado));
	}
	
}

public interface Interface_1
{
       public void converter();
       public void exibe();
}

bt_somar.addActionListener(this);
		bt_subtrair.addActionListener(this);
		bt_multiplicar.addActionListener(this);
		bt_dividir.addActionListener(this);
		bt_sair.addActionListener(this);
		bt_limpar.addActionListener(this);
		
		mi_somar.addActionListener(this);
		mi_subtrair.addActionListener(this);
		mi_multiplicar.addActionListener(this);
		mi_dividir.addActionListener(this);
		mi_limpar.addActionListener(this);
		mi_sair.addActionListener(this);

if(e.getSource() == bt_somar || e.getSource() == mi_somar)
		{
			double num1 = Double.parseDouble(tf_num1.getText());
			double num2 = Double.parseDouble(tf_num2.getText());
			double resultado = num1 + num2;
			//tf_resultado.setText(String.valueOf(resultado));
			tf_resultado.setText(""+resultado);
		}

objeto.addActionListener(this);

getText()

botao.addActionListener( new ActionListener() {
           public void actionPerformed( ActionEvent e ) {

           }
});

JButton button = new JButton()

public void buttonActionPerformed() {}

// Dentro do construtor
btnOk.addActionListener(new ActionListener() {
    public void actionPerformed(ActionEvent e) {
        btnOkActionPerformed(e);
    }
});

btnCancelar.addActionListener(new ActionListener() {
    public void actionPerformed(ActionEvent e) {
        btnCancelarActionPerformed(e);
    }
});

. . .

// No corpo da classe
private void btnOkActionPerformed(ActionEvent e) {
    . . .
}

private void btnCancelarActionPerformed(ActionEvent e) {
   . . .
}