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

public class CmPollici extends Frame implements ActionListener
{ 
   private TextField tf;
   private Button    bu;
   private Label     la;
   private Choice    ch;

   private final float FC=2.54f;

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

      // Centro
      ch=new Choice();          ch.addItem("DA cm A pollici");
                                ch.addItem("DA pollici A cm"); 
      bu=new Button("Calcola"); bu.addActionListener(this);
      Panel p=new Panel();      p.add(ch); 
                                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;

      switch(ch.getSelectedIndex())
      {
          case 0: r=f/FC; s=f + " cm = "      + r + " pollici"; break;
          case 1: r=f*FC; s=f + " pollici = " + r + " cm"     ; break;

         default: System.out.print("Errore."); 
      }

      la.setText(s); 
   }

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