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.");

}

}

}