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| - | In this part of the Java Gnome programming tutorial, we will do our first steps in programming.
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| - | We will create simple programs.
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| - | == Simple example ==
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| - |
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| - | The first code example is a simple one that shows a centered window.
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| - | <source lang="java">
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| - | package com.zetcode;
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| - | import org.gnome.gdk.Event;
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| - | import org.gnome.gtk.Gtk;
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| - | import org.gnome.gtk.Widget;
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| - | import org.gnome.gtk.Window;
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| - | import org.gnome.gtk.WindowPosition;
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| - |
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| - | /**
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| - | * ZetCode Java Gnome tutorial
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| - | *
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| - | * This program is a simple Java Gnome
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| - | * application.
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| - | *
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| - | * @author jan bodnar
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| - | * website zetcode.com
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| - | * last modified March 2009
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| - | */
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| - |
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| - | public class GSimple extends Window {
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| - | public GSimple() {
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| - |
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| - | setTitle("Simple");
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| - | connect(new Window.DeleteEvent() {
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| - | public boolean onDeleteEvent(Widget source, Event event) {
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| - | Gtk.mainQuit();
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| - | return false;
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| - | }
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| - | });
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| - | setDefaultSize(250, 150);
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| - | setPosition(WindowPosition.CENTER);
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| - | show();
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| - | }
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| - |
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| - | public static void main(String[] args) {
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| - | Gtk.init(args);
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| - | new GSimple();
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| - | Gtk.main();
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| - | }
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| - | }
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| - | </source>
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| - | The code example shows a small window in the center of the screen.
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| - | <source lang="java">
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| - | import org.gnome.gdk.Event;
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| - | import org.gnome.gtk.Gtk;
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| - | import org.gnome.gtk.Widget;
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| - | import org.gnome.gtk.Window;
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| - | import org.gnome.gtk.WindowPosition;
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| - | </source>
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| - |
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| - | We import all necessary objects.
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| - |
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| - | <source lang="java">
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| - | public class GSimple extends Window {
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| - | </source>
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| - | Our application is based on the <b>Window</b> class.
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| - | Window is a toplevel widget that is used as a container for other widgets.
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| - | <source lang="java">
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| - | setTitle("Simple");
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| - |
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| - | </source>
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| - | Here we set the title for the window.
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| - | <source lang="java">
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| - | connect(new Window.DeleteEvent() {
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| - | public boolean onDeleteEvent(Widget source, Event event) {
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| - | Gtk.mainQuit();
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| - | return false;
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| - | }
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| - | });
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| - | </source>
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| - |
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| - | This code cleanly exits the Java Gnome application, if we close the window.
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| - | <source lang="java">
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| - | setDefaultSize(250, 150);
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| - |
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| - | </source>
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| - | This line sets a default size for the window.
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| - | <source lang="java">
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| - | setPosition(WindowPosition.CENTER);
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| - | </source>
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| - | This line centers the window on the screen.
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| - | <source lang="java">
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| - | show();
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| - |
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| - | </source>
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| - | Now we show the window. The window is not visible, until we call the <b>show()</b> method.
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| - | <source lang="java">
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| - | public static void main(String[] args) {
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| - | Gtk.init(args);
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| - | new GSimple();
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| - | Gtk.main();
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| - | }
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| - | </source>
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| - | The <b>main()</b> method is the entry point to the application. It initiates and runs the program.
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| - |
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| - | [[image: Java_Gnome_faq_simple.png| center]]
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| - | == Icon ==
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| - | In the next example, we show the application icon. Most window managers display the icon in the left corner of the titlebar and also on the taskbar.
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| - | <source lang="java">
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| - | package com.zetcode;
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| - | import java.io.FileNotFoundException;
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| - | import org.gnome.gdk.Event;
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| - | import org.gnome.gdk.Pixbuf;
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| - | import org.gnome.gtk.Gtk;
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| - | import org.gnome.gtk.Widget;
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| - | import org.gnome.gtk.Window;
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| - | import org.gnome.gtk.WindowPosition;
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| - | /**
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| - | * ZetCode Java Gnome tutorial
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| - | *
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| - | * This program shows a small icon
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| - | * in the top left corner of the window.
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| - | *
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| - | * @author jan bodnar
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| - | * website zetcode.com
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| - | * last modified March 2009
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| - | */
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| - | public class GIcon extends Window implements Window.DeleteEvent {
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| - | Pixbuf icon;
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| - | public GIcon() {
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| - | setTitle("Icon");
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| - |
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| - | initUI();
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| - | connect(this);
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| - |
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| - | setDefaultSize(250, 150);
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| - | setPosition(WindowPosition.CENTER);
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| - | show();
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| - | }
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| - | public void initUI() {
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| - | try {
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| - | icon = new Pixbuf("web.png");
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| - | } catch (FileNotFoundException e) {
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| - | e.printStackTrace();
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| - | }
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| - |
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| - | setIcon(icon);
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| - | }
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| - | public boolean onDeleteEvent(Widget widget, Event event) {
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| - | Gtk.mainQuit();
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| - | return false;
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| - | }
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| - | public static void main(String[] args) {
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| - | Gtk.init(args);
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| - | new GIcon();
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| - | Gtk.main();
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| - | }
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| - | }
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| - | </source>
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| - | The code example shows the application icon.
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| - | <source lang="java">
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| - | initUI();
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| - | </source>
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| - | We delegate the setup of the user interface to the <b>initUI()</b> method.
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| - | <source lang="java">
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| - | try {
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| - | icon = new Pixbuf("web.png");
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| - | } catch (FileNotFoundException e) {
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| - | e.printStackTrace();
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| - | }
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| - | </source>
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| - | We load a pixbuf from the file on the disk.
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| - | <source lang="java">
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| - | setIcon(icon);
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| - | </source>
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| - | The <b>setIcon()</b> method sets an icon for the window.
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| - | [[image: Java_Gnome_faq_icon.png| center]]
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| - | == Buttons ==
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| - | In the next example, we will further enhance our programming skills with the Java Gnome library.
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| - | <source lang="java">
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| - | package com.zetcode;
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| - | import org.gnome.gdk.Event;
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| - | import org.gnome.gtk.Button;
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| - | import org.gnome.gtk.Fixed;
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| - | import org.gnome.gtk.Gtk;
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| - | import org.gnome.gtk.Stock;
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| - | import org.gnome.gtk.Widget;
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| - | import org.gnome.gtk.Window;
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| - | import org.gnome.gtk.WindowPosition;
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| - | /**
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| - | * ZetCode Java Gnome tutorial
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| - | *
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| - | * This program shows four buttons
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| - | * with different characteristics.
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| - | *
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| - | * @author jan bodnar
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| - | * website zetcode.com
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| - | * last modified March 2009
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| - | */
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| - | public class GButtons extends Window {
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| - | public GButtons() {
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| - | setTitle("Buttons");
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| - | initUI();
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| - | connect(new Window.DeleteEvent() {
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| - | public boolean onDeleteEvent(Widget source, Event event) {
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| - | Gtk.mainQuit();
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| - | return false;
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| - | }
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| - | });
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| - | setDefaultSize(250, 200);
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| - | setPosition(WindowPosition.CENTER);
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| - | showAll();
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| - | }
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| - | public void initUI() {
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| - | Fixed fix = new Fixed();
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| - | Button btn1 = new Button("Button");
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| - | btn1.setSensitive(false);
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| - | Button btn2 = new Button("Button");
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| - | Button btn3 = new Button(Stock.CLOSE);
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| - | Button btn4 = new Button("Button");
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| - | btn4.setSizeRequest(80, 40);
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| - | fix.put(btn1, 20, 30);
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| - | fix.put(btn2, 100, 30);
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| - | fix.put(btn3, 20, 80);
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| - | fix.put(btn4, 100, 80);
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| - | add(fix);
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| - | }
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| - | public static void main(String[] args) {
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| - | Gtk.init(args);
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| - | new GButtons();
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| - | Gtk.main();
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| - | }
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| - | }
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| - | </source>
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| - | We show four different buttons on the window. We will see a difference between container widgets and child widgets and will change some properties of child widgets.
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| - | <source lang="java">
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| - | Fixed fix = new Fixed();
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| - | </source>
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| - | <b>Fixed</b> widget is a non visible container widget. It's purpose is to contain other child widgets.
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| - | <source lang="java">
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| - | Button btn1 = new Button("Button");
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| - | </source>
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| - | A <b>Button</b> is a child widget. Child widgets are placed inside containers.
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| - | <source lang="java">
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| - | btn1.setSensitive(false);
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| - | </source>
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| - | We make this button insensitive. This means, we cannot click on it. Graphically the widget is grayed out.
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| - | <source lang="java">
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| - | Button btn3 = new Button(Stock.CLOSE);
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| - | </source>
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| - | The third button shows an image inside it's area. The Java Gnome library has a built-in stock of images, that we can use.
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| - | <source lang="java">
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| - | btn4.setSizeRequest(80, 40);
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| - | </source>
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| - | Here we change the size of the button.
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| - | <source lang="java">
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| - | fix.put(btn1, 20, 30);
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| - | fix.put(btn2, 100, 30);
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| - | ...
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| - | </source>
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| - | Here we place button widgets inside fixed container widget.
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| - | <source lang="java">
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| - | add(fix);
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| - | </source>
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| - | We set the <b>Fixed</b> container to be the main container for our <b>Window</b> widget.
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| - | <source lang="java">
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| - | showAll();
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| - | </source>
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| - | We can either call <b>showAll()</b> method, which shows all widgets at once, or we call <b>show()</b> method on each of the widgets.
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| - | Including containers.
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| - | [[image: Java_Gnome_faq_buttons.png| center]]
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| - | In this chapter, we created first programs in Java Gnome programming library.
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| - | [[Категория:GTK+]]
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| - | [[Категория:Java]]
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