PC Plus SuperCD (UK) 1997 May/PC Plus Super CD Issue 127 (May 1997).iso/handson/java/classes/frame1.java

Java Source | 1997-02-07 | 5.2 KB | 216 lines

/*
    PC Plus sample Java app.
    Demonstrates the definition of user-defined Classes.
*/

import java.awt.*;
import java.util.*;

public class Frame1 extends Frame {

    Vector v = new Vector();

    void button1_Clicked(Event event) {
        // v is a Vector of mixed Objects.
        // This method checks the Object types using 'instanceof'
        // Then it prints the results into a List box.

        list1.clear();
        for (Enumeration e = v.elements(); e.hasMoreElements(); ) {
            Thing t = (Thing)e.nextElement();
            list1.addItem(t.getName());
            list1.addItem(t.getDescription());
            if (t instanceof Object)
                list1.addItem("[This is an Object]");
            if (t instanceof Thing)
                list1.addItem("[This is a Thing]");
            if (t instanceof Creature)
                list1.addItem("[This is a Creature] species = " + ((Creature) t).getSpecies());
            if (t instanceof Treasure)
                list1.addItem("[This is a Treasure] value = " + ((Treasure) t).getValue());
            list1.addItem( "--------------------" );

        }


    }

    void Open_Action(Event event) {
        OpenFileDialog.show();
    }

    void About_Action(Event event) {
        (new AboutDialog(this, "About...", false)).show();
    }

    void Exit_Action(Event event) {
        (new QuitDialog(this, "Quit the Application?", false)).show();
    }

    public Frame1() {

        //{{INIT_CONTROLS
        setLayout(null);
        addNotify();
        resize(insets().left + insets().right + 431,insets().top + insets().bottom + 464);
        OpenFileDialog = new java.awt.FileDialog(this, "Open",FileDialog.LOAD);
        list1 = new java.awt.List(0,false);
        add(list1);
        list1.reshape(insets().left + 7,insets().top + 8,416,345);
        button1 = new java.awt.Button("Display My Objects!");
        button1.reshape(insets().left + 133,insets().top + 383,159,39);
        add(button1);
        setTitle("A Basic Application");
        //}}

        //{{INIT_MENUS
        mainMenuBar = new java.awt.MenuBar();

        menu1 = new java.awt.Menu("File");
        menu1.add("Open...");
        menu1.add("Save");
        menu1.add("Save As...");
        menu1.addSeparator();
        menu1.add("Exit");
        mainMenuBar.add(menu1);

        menu2 = new java.awt.Menu("Edit");
        menu2.add("Cut");
        menu2.add("Copy");
        menu2.add("Paste");
        mainMenuBar.add(menu2);

        menu3 = new java.awt.Menu("Help");
        menu3.add("About");
        mainMenuBar.add(menu3);
        setMenuBar(mainMenuBar);
        //}}
    }

    public Frame1(String title) {
        this();
        setTitle(title);
    }

    public synchronized void show() {
        move(50, 50);
        super.show();

    v.addElement( new Thing("A Wotsit", "An ordinary Thing"));
    v.addElement( new Creature("A Troll", "A nasty fellow", "Trollus trollidus" ));
    v.addElement( new Treasure("A Sword", "A jewel-encrusted weapon", 550));

    }

    public boolean handleEvent(Event event) {
        if (event.id == Event.WINDOW_DESTROY) {
            hide();         // hide the Frame
            dispose();
            System.exit(0);
            return true;
        }
        if (event.target == button1 && event.id == Event.ACTION_EVENT) {
            button1_Clicked(event);
        }
        return super.handleEvent(event);
    }

    public boolean action(Event event, Object arg) {
        if (event.target instanceof MenuItem) {
            String label = (String) arg;
            if (label.equalsIgnoreCase("Open...")) {
                Open_Action(event);
                return true;
            } else
            if (label.equalsIgnoreCase("About")) {
                About_Action(event);
                return true;
            } else
            if (label.equalsIgnoreCase("Exit")) {
                Exit_Action(event);
                return true;
            }
        }
        return super.action(event, arg);
    }

    static public void main(String args[]) {
        (new Frame1()).show();
    }

    //{{DECLARE_CONTROLS
    java.awt.FileDialog OpenFileDialog;
    java.awt.List list1;
    java.awt.Button button1;
    //}}

    //{{DECLARE_MENUS
    java.awt.MenuBar mainMenuBar;
    java.awt.Menu menu1;
    java.awt.Menu menu2;
    java.awt.Menu menu3;
    //}}
}


// ---- OUR OWN USER-DEFINED CLASS HIERARCHY ----
// class Thing
// any object that has a name and a description
class Thing {
    private String name;
    private String description;

    Thing( String aName, String aDescription) {
        this.name = aName;
        this.description = aDescription;
    }

    String getName() {
        return name;
    }

    void setName(String aName) {
        this.name = aName;
    }

    String getDescription() {
        return description;
    }

    void setDescription(String aDescription) {
        this.description = aDescription;
    }
} // END: class Thing


// class Creature
// a descendent of Thing which also has a 'species'
class Creature extends Thing {
    private String species;

    Creature( String aName, String aDescription, String aSpecies ) {
        super( aName, aDescription );
        this.species = aSpecies;
    }

   String getSpecies() {
        return species;
   }

}

// class Treasure
// a descendent of Thing which also has a 'value'
class Treasure extends Thing {
    private int value;

    Treasure( String aName, String aDescription, int aValue ) {
        super( aName, aDescription );
        this.value = aValue;
    }

   int getValue() {
        return value;
   }

}