import java.awt.Button;
import java.awt.TextField;
import java.awt.Label;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.applet.Applet;

public class sqrt_c
  extends Applet
{

  // Inre klass för att lyssna på knapp
  private class sqrt_btn_listener_c
    implements ActionListener
  {
    public void actionPerformed( ActionEvent aev )
    {
      handle_sqrt_btn();
    }
  }

  // Hantera klick på roten-ur-knapp
  private void handle_sqrt_btn()
  {
    String numbuf = this.num_edt.getText();
    boolean okay = false;
    float num = 0;
    try
    {
      num = new Float( numbuf ).floatValue(); 
      // !!! Float.parseFloat( numbuf ); gick inte i IE !!!
      num = (float)Math.sqrt( num );

      okay = !Float.isNaN( num );
    }
    catch ( Exception exc )
    {
    }

    if ( okay )
    {
      this.sqrt_lbl.setText( 
        "Roten ur " +
        numbuf +
        " = " +
        Float.toString( num ) );
    }
    else
    {
      this.sqrt_lbl.setText( "Det måste vara ett positivt tal." );
    }
  } // handle_sqrt_btn


  public void init()
  {
    super.init();
    super.setLayout( null );

    this.num_edt = new TextField( "SKRIV TAL HÄR" );
    super.add( this.num_edt );
    this.num_edt.setBounds( 20, 20, 120, 20 );

    this.sqrt_lbl = new Label( "HÄR VISAS ROTEN" );
    super.add( this.sqrt_lbl );
    this.sqrt_lbl.setBounds( 20, 50, 200, 20 );

    Button sqrt_btn;
    sqrt_btn_listener_c sqrt_btn_listener = new sqrt_btn_listener_c();
    sqrt_btn = new Button( "VISA ROT" );
    sqrt_btn.addActionListener( sqrt_btn_listener );
    super.add( sqrt_btn );
    sqrt_btn.setBounds( 150, 20, 100, 20 );
  } // init

  private Label sqrt_lbl;
  private TextField num_edt;
} // sqrt_c