How to make a check box appear to the user when he does a specific action

Question

hi all
i have created a check box and i want if the user does not do a specific action the check box appears ?

Answer 1

so sorry i ment a frame with an error message
remember my last program about randomization
i want if the user did not enter the first name
a message appear to warn
and if he did not enter the second name
a message appear to warn
here i created a created a second frame to appear as
awarning message
and the action to allow the error frame to appear
else
c2.setVisible();
but the compiler didnot recognized c2
is that not legal to create two objects from
container c2=getcontentpane();
i want to understand this problem
and making my code right
and making my code right
Code:
import java.awt.*;
import javax.swing.*;
import java.io.*;
import java.awt.event.*;
class MyMatching extends JFrame
     final JTextField txt1=new JTextField("Name1",10);
     JLabel lbl3=new JLabel("Love");
     final JTextField txt2=new JTextField("Name2",10);
     JButton btn=new JButton("Result");
     JTextField txt3=new JTextField("%",5);
     JTextArea ta=new JTextArea(10,40);
     ImageIcon img=new ImageIcon("D:\\Mastering Java\\Java Projects\\Icons\\alert_lrg.gif ");
     JLabel lbl=new      JLabel(" Do You Love Computer Science?",img,JLabel.LEFT);
     JPanel pnl1=new JPanel();
     JPanel pnl2=new JPanel();
JPanel pnl3=new JPanel();
     MyInner inner;
     MyMatching()
          setupGUI();
     private void setupGUI()
          setSize(500,300);
          setTitle("Love Matching v1");
          Container c=getContentPane();
     Container c2=getContentPane();
          c.setLayout(new BorderLayout());
          pnl3.setLayout(new BorderLayout());
          pnl1.setLayout(new FlowLayout());
pnl1.add(txt1);
pnl1.add(lbl3);
pnl1.add(txt2);
pnl1.add(btn);
pnl1.add(txt3);
pnl2.add(ta);
c.add("North",pnl1);
c.add("Center",pnl2);
lbl.setIcon(img);
     pnl3.add("Center",lbl);
     c2.add(pnl3);
setVisible(true);
inner=new MyInner ();     
btn.addActionListener( inner);
// txt1.addActionListener( inner);
// txt2.addActionListener( inner);
class MyInner implements ActionListener
public void actionPerformed(ActionEvent e)
if(!txt1.getText().equals("Name1") && !txt2.getText().equals("Name2"))
     if (e.getActionCommand().equals("Result"))
//First process
int random= ((int)(50*Math.random()))+50;
txt3.setText(random+"%");
//second process
String msg[ ]={"Love Can Touch Us One Time And Last For The Life Time\nYou Are A True Lovers.","Your Feelings Are Different \nYou Should Forget it."
,"Love Is A Passion\nYou Must Be More Romantic.","You Are An Angel\n But Your Lover Is A Liar."
,"You Must Think Deeply Before That Choice\nLove Is Not An Entertainment.","Do Not Lie To Your Hart\nYou Still Love Your First Lover."
,"You Cannot Love Again\nYour First Lover is So Lovely And Cannot Be Forotten."};
ta.setText( msg[((int)( msg.length*Math.random()))] );
/* breaking up the code
double random = Math.random();
int index = (int) (msg.length*random);
String message = msg[index];
ta.setText(message);*/
ta.setForeground(Color.RED);
else
c2.setVisible();
     public static void main(String[]args)
          MyMatching mtch=new MyMatching();
}