阅读下列程序，请写出该程序的功能。
import java.awt.*; import javax.swing.*;import java.applet.*; import java.awt.event.*;
public class Class l extends Applet implements ActionListener{
JTextField Text I =new JTextField(5);
JTextField Text2=new JTextField(5);
JTextField Text3=new JTextField(5);
JLabel Label 1 =new JLabel("Please input three numbers:");
JLabel Label2=new JLabel(" ");
JButton but=new JButton("Start!");
public void init() {
setLayout(new GridLayout(6,1));
add (Label 1);
add (Textl);
add (Text2);
add (Text3);
add (but);
add (Label2);
Label2.setFont(new Font ("Courier", 1, 20));
but.addActionListener(this);
}
public void actionPerformed(ActionEvent e) {
int a,b,c; a=Integer.parseInt(Text 1.getText());
b=Integer.parselnt(Text2.getText());
c=Integer.parselnt(Text3.getText());
if (a + b < c || b + c < a || c + a < b) {
Label2 .setForeground (Color. red );
Label2.setFont(new Font ("Courier ", 1, 24));
Label2.setText("No.");
}
else {
Label2.setForeground(Color.blue);
Label2.setFont(new Font ("Courier ", 2, 24));
Label2.setText(" Yes.");
}
}
}