问答题

阅读下列程序，请写出程序的功能。
import java.util.* ;import java.io. * ;import java.awt. * ;import javax.swing. * ;
import java. awt. event. * ;
public class Test35 extends JFrame implements ActionListener{
JTextArea text; JButton button; BufferedWriter out;
TesB5 () {
super("一个测试程序");
Container con=getContentPane();
text=new JTextArea(10,20); text.setBackground (Color.cyan);
button=new JButton ("写"); button.addActionListener(this);
con.setLayout(new BorderLayout());
con.add (text, "Center"); con.add(button, "South");
setVisible(true);pack();
}
public void actionPerformed(ActionEvent e) {
String s;
if (e. getSource()== button) {
try {
out=new BufferedWriter(new FileWriter("line.txt"));
s=text.getText();
StringTokenizer tokens=new StringTokenizer(s);
int n=tokens.countTokens(),i;
String temp=tokens.nextToken();
out.write(temp+"\r\n");
}
out.flush (); text.setText (null) ;System.exit(0);
}catch(IOException exp){
text.setText("文件写出错! \n");
}
}
}
public static void main(String args[ ]) {new Test35 ();}
}