Copy the code book error: not abstract and does not override abstract method in java.awt.event.KeyListener KeyReleased

The following code error:
Dazi not abstract and does not override abstract method in java.awt.event.KeyListener KeyReleased (java.awt.event.KeyEvent)

import java.text.DecimalFormat;
import javax.swing.border. *;
import javax.swing.border.EtchedBorder;
import javax.swing. *;
import java.awt. *;
import java.awt.event. *;
public class Dazi extends JPanel implements KeyListener {
JLabel lbl1, lbl2, lbl3, lbl4, msg;
String str = "When Isaac Newton said \" Every action has an equal and opposite reaction \ "he demonstrated he knew a lot about

physics and absolutely nothing about women. ";
String substr = "";
JTextArea txt;
int index = 0;
double count = 0;
DecimalFormat form1 = new DecimalFormat ("0.000"); / / Specifies the digital output format retains three decimal places
public static void main (String args []) {
JFrame f = new JFrame (" practice English typing " ) ;
Dazi da = new Dazi ();
JPanel pane = da.init ();
JPanel p = new JPanel ();
f.getContentPane (). add (pane);
f.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
f.setSize (300,250);
f.setVisible (true);
}
public JPanel init () {
JPanel p = new JPanel (new FlowLayout (FlowLayout.LEADING));
lbl1 = new JLabel ("When Isaac Newton said \" Every action ");
lbl2 = new JLabel ("has an equal and opposite reaction \" " ) ;
lbl3 = new JLabel ("he demonstrated he knew a lot about physics" ) ;
lbl4 = new JLabel ("and absolutely nothing about women.");
msg = new JLabel (" Please enter the text above " ) ;
txt = new JTextArea (5,25);
txt.setEditable (false);
txt.setLineWrap (true); / / set word wrap
/ * txt.setBorder (BorderFactory.cteateEtchedBorder (EtchedBorder.RAISED)); * /
p.add (lbl1); p.add (lbl2); p.add (lbl3) ; p.add (lbl4);
p.add (msg); p.add (txt);
txt.addKeyListener (this);
return p;
}
public void KeyTyped (KeyEvent e) {
count + +;
if (index! = str.length ()) {
if (String.valueOf (e.getKeyChar ()). equals (str.substring (index, index +1))) {
substr = str.substring ( 0, index +1);
txt.setText (substr) ;
index + +;
}
}
if (index == str.length ())
msg.setText (" Your error rate : "+ form1.format (1-index/count));
}
public void KeyPressed (KeyEvent e) {}
public void KeyReleased (KeyEvent e) {}
}

------ Solution ------------------------------------ --------
there are several ways you did not realize :
no problem with this :

  import java.text.DecimalFormat;
  import javax.swing.border.*;
  import javax.swing.*;
  import java.awt.*;
  import java.awt.event.*;
  
  public class Dazi extends JPanel implements KeyListener {
  	JLabel lbl1, lbl2, lbl3, lbl4, msg;
  	String str = "When Isaac Newton said\"Every action has an equal and opposite reaction\"he demonstrated he knew a lot about physics and absolutely nothing about women.";
  	String substr = "";
  	JTextArea txt;
  	int index = 0;
  	double count = 0;
  	DecimalFormat form1 = new DecimalFormat("0.000"); // 指定数字输出格式保留3位小数
  
  	public static void main(String args[]) {
  		JFrame f = new JFrame("练习英文打字");
  		Dazi da = new Dazi();
  		JPanel pane = da.init();
  		JPanel p = new JPanel();
  		f.getContentPane().add(pane);
  		f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  		f.setSize(300, 250);
  		f.setVisible(true);
  	}
  
  	public JPanel init() {
  		JPanel p = new JPanel(new FlowLayout(FlowLayout.LEADING));
  		lbl1 = new JLabel("When Isaac Newton said\"Every action");
  		lbl2 = new JLabel("has an equal and opposite reaction\"");
  		lbl3 = new JLabel("he demonstrated he knew a lot about physics");
  		lbl4 = new JLabel("and absolutely nothing about women.");
  		msg = new JLabel("请输入上面的文字");
  		txt = new JTextArea(5, 25);
  		txt.setEditable(false);
  		txt.setLineWrap(true); // 设置自动换行
  		/* txt.setBorder(BorderFactory.cteateEtchedBorder(EtchedBorder.RAISED)); */
  		p.add(lbl1);
  		p.add(lbl2);
  		p.add(lbl3);
  		p.add(lbl4);
  		p.add(msg);
  		p.add(txt);
  		txt.addKeyListener(this);
  		return p;
  	}
  
  	public void KeyTyped(KeyEvent e) {
  		count++;
  		if (index != str.length()) {
  			if (String.valueOf(e.getKeyChar()).equals(
  					str.substring(index, index + 1))) {
  				substr = str.substring(0, index + 1);
  				txt.setText(substr);
  				index++;
  			}
  		}
  		if (index == str.length())
  			msg.setText("您的错误率为：" + form1.format(1 - index / count));
  	}
  
  	public void KeyPressed(KeyEvent e) {
  	}
  
  	public void KeyReleased(KeyEvent e) {
  	}
  
  	@Override
  	public void keyPressed(KeyEvent arg0) {
  		// TODO Auto-generated method stub
  
  	}
  
  	@Override
  	public void keyReleased(KeyEvent arg0) {
  		// TODO Auto-generated method stub
  
  	}
  
  	@Override
  	public void keyTyped(KeyEvent arg0) {
  		// TODO Auto-generated method stub
  
  	}
  }