// This file contains excerpts from the textbook Concrete
// Abstractions: An Introduction to Computer Science Using Scheme, by
// Max Hailperin, Barbara Kaiser, and Karl Knight, Copyright (c) 1998
// by the authors. Full text is available for free at
// http://www.gustavus.edu/+max/concrete-abstractions.html

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

public class FormattedField extends TextField implements ActionListener {
  
  private double value;
  private java.text.Format fmt;

  public FormattedField(int width, java.text.Format f){
    super(width);
    fmt = f;
    addActionListener(this);
  }
  
  public void actionPerformed(ActionEvent evt){
    try{
      valueEntered(fmt.parseObject(getText()));
    } catch(java.text.ParseException e){
      // illegal entry, leave alone
    }
  }

  public void valueEntered(Object value){
    // typically a subclass will override this
  }

  public void setValue(Object value){
    setText(fmt.format(value));
  }
}