/* * Copyright ? 2002 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, * California 95054, U.S.A. All rights reserved.  Sun Microsystems, Inc. has * intellectual property rights relating to technology embodied in the product * that is described in this document. In particular, and without limitation, * these intellectual property rights may include one or more of the U.S. * patents listed at http://www.sun.com/patents and one or more additional * patents or pending patent applications in the U.S. and in other countries. * U.S. Government Rights - Commercial software. Government users are subject * to the Sun Microsystems, Inc. standard license agreement and applicable * provisions of the FAR and its supplements.  Use is subject to license terms. * Sun,  Sun Microsystems,  the Sun logo and  Java are trademarks or registered * trademarks of Sun Microsystems, Inc. in the U.S. and other countries.  This * product is covered and controlled by U.S. Export Control laws and may be * subject to the export or import laws in other countries.  Nuclear, missile, * chemical biological weapons or nuclear maritime end uses or end users, * whether direct or indirect, are strictly prohibited.  Export or reexport * to countries subject to U.S. embargo or to entities identified on U.S. * export exclusion lists, including, but not limited to, the denied persons * and specially designated nationals lists is strictly prohibited. */import java.awt.*;public class CalcGUI extends Frame implements CalcInputParserConstants {  /**   * A button object is created for each calculator button.  Since   * there is going to be only one calculator GUI, these objects can   * be static.   */  static Button one = new Button("1");  static Button two = new Button("2");  static Button three = new Button("3");  static Button four = new Button("4");  static Button five = new Button("5");  static Button six = new Button("6");  static Button seven = new Button("7");  static Button eight = new Button("8");  static Button nine = new Button("9");  static Button zero = new Button("0");  static Button dot = new Button(".");  static Button equal = new Button("=");  static Button add = new Button("+");  static Button sub = new Button("-");  static Button mul = new Button("*");  static Button div = new Button("/");  static Button quit = new Button("QUIT");  /**   * The display window with its initial setting.   */  static Label display = new Label("0 ");  /**   * The class that collects the characters produced by the GUI   */  static final CharCollector collector = new CharCollector();  static final CharStream getCollector()  {     return collector;  }  /**   * string that holds what the calculator displays   */  static String label = "0";  /**   * flag to indicate if this is the first digit.   */  static boolean firstDigit = true;  /**   * Indicates an error has occured    */  static boolean error = false;  /**   * Constructor that creates the full GUI.  This is called by the   * main program to create one calculator GUI.   */  public CalcGUI() {    super("Calculator");    GridBagLayout gb = new GridBagLayout();    setLayout(gb);    GridBagConstraints gbc = new GridBagConstraints();    display.setFont(new Font("TimesRoman", Font.BOLD, 18));    display.setAlignment(Label.RIGHT);    gbc.gridwidth = GridBagConstraints.REMAINDER;    gbc.fill = GridBagConstraints.BOTH;    gbc.weightx = 1.0;    gbc.weighty = 0.0;    gb.setConstraints(display, gbc);    add(display);    Panel buttonPanel = new Panel();    buttonPanel.setFont(new Font("TimesRoman", Font.BOLD, 14));    buttonPanel.setLayout(new GridLayout(4,4));    buttonPanel.add(one); buttonPanel.add(two); buttonPanel.add(three); buttonPanel.add(four);    buttonPanel.add(five); buttonPanel.add(six); buttonPanel.add(seven); buttonPanel.add(eight);    buttonPanel.add(nine); buttonPanel.add(zero); buttonPanel.add(dot);  buttonPanel.add(equal);    buttonPanel.add(add); buttonPanel.add(sub); buttonPanel.add(mul); buttonPanel.add(div);    gbc.weighty = 1.0;    gb.setConstraints(buttonPanel, gbc);    add(buttonPanel);    quit.setFont(new Font("TimesRoman", Font.BOLD, 14));    gbc.gridheight = GridBagConstraints.REMAINDER;    gbc.weighty = 0.0;    gb.setConstraints(quit, gbc);    add(quit);    pack();    show();  }  /**   * Here we just return the character that is input.   */  public boolean handleEvent(Event evt) {    char c = 0;     if (evt.id != Event.ACTION_EVENT) {      return false;    }    if (evt.target == quit) {      System.exit(0);    }    if (error)    {       if (evt.target == zero)       {          error = false;          print("0");          firstDigit = true;          return true;       }       return false;    }    if (evt.target == equal) {      c = '=';      firstDigit = true;    }    else if (evt.target == add) {      c = '+';      label = "0";      firstDigit = true;    }    else if (evt.target == sub) {      c = '-';      label = "0";      firstDigit = true;    }    else if (evt.target == mul) {      c = '*';      label = "0";      firstDigit = true;    }    else if (evt.target == div) {      c = '/';      label = "0";      firstDigit = true;    }    else     {      if (firstDigit)         label = "";      firstDigit = false;      if (evt.target == one) {        c = '1';        label += c;      }      else if (evt.target == two) {        c = '2';        label += c;      }      else if (evt.target == three) {        c = '3';        label += c;      }      else if (evt.target == four) {        c = '4';        label += c;      }      else if (evt.target == five) {        c = '5';        label += c;      }      else if (evt.target == six) {        c = '6';        label += c;      }      else if (evt.target == seven) {        c = '7';        label += c;      }      else if (evt.target == eight) {        c = '8';        label += c;      }      else if (evt.target == nine) {        c = '9';        label += c;      }      else if (evt.target == zero) {        c = '0';        label += c;      }      else if (evt.target == dot) {        c = '.';        label += ".";      }      else        return false;    }    print(label);    collector.put(c);    return true;  }  public static void print(double value) {    display.setText(label = Double.toString(value));  }  public static void print(String image) {    display.setText(label = image);  }  public static void Error(String image) {     print(image);     Toolkit.getDefaultToolkit().beep();     collector.Clear();     label = "0";     error = true;  }}