import java.awt.*;
import java.awt.event.*;

public class CmPollici extends Frame implements ActionListener
{ 
   private TextField     tf;
   private Button        bu;
   private Label         la;
   private Checkbox      cb1, cb2; 
   private CheckboxGroup cg; 

   private final float FC=2.54f;

   public CmPollici()
   {
      // Nord
      tf=new TextField("Input"); 
      this.add(tf, BorderLayout.NORTH); 

      // Centro 
      cg=new CheckboxGroup();   cb1=new Checkbox("DA cm A pollici", cg, true);
                                cb2=new Checkbox("DA pollici A cm", cg, false);
      bu=new Button("Calcola"); bu.addActionListener(this); 
      Panel p=new Panel();      p.add(cb1);
                                p.add(cb2);
                                p.add(bu);
      this.add(p, BorderLayout.CENTER); 

      // Sud
      la=new Label("Output", Label.CENTER); 
      this.add(la, BorderLayout.SOUTH ); 

      // Globale
      this.pack(); 
      this.setVisible(true);
   }

   public void actionPerformed(ActionEvent ae)
   {
      String s="";
      float  f=Float.parseFloat(tf.getText()); 
      float  r=0.0f;

      Object o=cg.getSelectedCheckbox();
      if(o == cb1)      { r=f/FC; s=f + " cm = "      + r + " pollici"; }
      else if(o == cb2) { r=f*FC; s=f + " pollici = " + r + " cm"     ; }

      la.setText(s);
   }

   public static void main(String[] args)
   { 
      CmPollici f=new CmPollici();
   }
}