[DÚVIDA] Calculadora

import java.awt.*;
import java.awt.Event.*;
import java.awt.event.ActionEvent;
import javax.swing.*;

public class Calc extends JFrame implements ActionListener, ListenerText //ActionListener e ListenerText estão apontando erro.
{
	JLabel L1, L2, L3;
	JButton B1, B2, B3, B4, B5;
	JTextField T1, T2, T3;
	
	public static void main(String []args)
	{
		JFrame Janela = new Calc();
		Janela.show();
		//
		[b]WindowListener x = new WindowAdapter()[/b] //Essa linha esta com erro.
		{
			public void windowClosing(WindowEvent e)
			{
				System.exit(0);
			}
		};
		Janela.addWindowListener(x);
	}
	
	Calc()
	{
		setTitle("Calculadora");
		setSize(390, 90);
		setLocation(50, 50);
		getContentPane().setBackground(new Color(150, 150, 150));
		getContentPane().setLayout(new GridLayout(3, 4));
		//LABELS
		L1 = new JLabel("num.1");
		L1.setForeground(Color.black);
		L1.setFont(new Font("", Font.BOLD, 14));
		L2 = new JLabel("num.2");
		L2.setForeground(Color.black);
		L2.setFont(new Font("", Font.BOLD, 14));
		L3 = new JLabel("total");
		L3.setFont(new Font("", Font.BOLD, 14));
		//BOTÕES
		B1 = new JButton("+"); /*FUNÇÂO  ---> */ B1.addActionListener(this);//ERRO
		B2 = new JButton("-");                   B2.addActionListener(this);//ERRO
		B3 = new JButton("*");                   B3.addActionListener(this);//ERRO
		B4 = new JButton("/");                   B4.addActionListener(this);//ERRO
		B5 = new JButton("Limpar");              B5.addActionListener(this);//ERRO
		B5.setBackground(Color.black);
		B5.setForeground(Color.white);
		
		T1 = new JTextField();
		T2 = new JTextField();
		T3 = new JTextField();
		T3.setEditable(false);
		
		getContentPane().add(L1);  
		getContentPane().add(T1);  
		getContentPane().add(B1);  
		getContentPane().add(B2);  
		getContentPane().add(L2);  
		getContentPane().add(T2);  
		getContentPane().add(B3);  
		getContentPane().add(B4);  
		getContentPane().add(L3);  
		getContentPane().add(T3);  
		getContentPane().add(B5);
		
		}
	public void actionPerformed(ActionEvent e)
	{
		if(e.getSource() == B5)
		{
			T1.setText("");
			T2.setText("");
			T3.setText("");
			return 0;//ERRO
		}
		float n1 = 0, n2 = 0, result = 0;
		try
		{
			n1 = Float.parseFloat(T1.getText());
			n2 = Float.parseFloat(T2.getText());
		}
		catch(NumberFormatException error)
		{
			T3.setText("ERRO!");
			return;
		}
		if(e.getSource() == B1)
		   { result = n1 + n2; }
		if(e.getSource() == B2)
		   { result = n1 - n2; }
		if(e.getSource() == B3)
		   { result = n1 * n2; }
		if(e.getSource() == B4)
		   { result = n1 / n2; }
		T3.setText("" + result);
	}
	public void textValueChanged(TextEvent e) //TextEvent esta apontando erro
	{
		T3.setText("Ola!!");
	}

}