Package :
Java.awt
Class:
java.awt.Canvas
Note : A Canvas component represents a
blank rectangular area of the screen onto which the application can
draw or from which the application can trap input events from the
user.
Constructors of Canvas Class
| Name |
Description |
Canvas() |
This constructor creates instance of a Canvas. |
Canvas(GraphicsConfiguration config) |
This constructor creates instance of a Canvas with the
given object of GraphicsConfiguration. |
Methods of Canvas Class
| Method |
Description |
getAccessibleContext() |
This method gets the accessible context of Canvas. |
getBufferStrategy() |
This method gets the Buffer Strategy. |
paint(Graphics g) |
This method paint the Canvas |
update(Graphics g) |
update the Canvas. |
createBufferStrategy(int numBuffers) |
This method creates the BufferStrategy. |
Example :
package com.techknow.canvas;
import java.awt.Canvas;
import java.awt.Graphics;
import java.awt.PrintJob;
import java.awt.Toolkit;
import java.util.Properties;
import java.awt.Dimension;
import java.awt.Frame;
import java.awt.SystemColor;
public class CanvasDemo extends Frame
{
MyCanvas canvas = new MyCanvas();
public CanvasDemo()
{
add("Center", canvas);
setSize(500, 500);
setVisible(true);
String name = "Test print job";
Properties properties = new Properties();
PrintJob pj = Toolkit.getDefaultToolkit()
.getPrintJob(CanvasDemo.this,
name, properties);
if (pj != null)
{
canvas.printAll(pj.getGraphics());
pj.end();
}
}
private void jbInit() throws Exception
{
this.setLayout( null );
this.setSize(new Dimension(390, 217));
this.setBackground( SystemColor.control );
}
public static void main(String args[])
{
CanvasDemo app = new CanvasDemo();
}
}
class MyCanvas extends Canvas
{
public void paint(Graphics g)
{
Dimension size = getSize();
int width = size.width;
int height = size.height;
int x1 = (int) (width * 0.1);
int x2 = (int) (width * 0.9);
int y1 = (int) (height * 0.1);
int y2 = (int) (height * 0.9);
g.drawRect(x1, y1, x2 - x1, y2 - y1);
g.drawOval(x1, y1, x2 - x1, y2 - y1);
g.drawLine(x1, y1, x2, y2);
g.drawLine(x2, y1, x1, y2);
String text = "Print Me! ";
text += text;
text += text;
g.drawString(text, x1, (int) ((y1 + y2) / 2));
g.dispose();
}
}
Output :
Package :
Java.awt
Class:
java.awt.Menu
Note :A Menu object is a drop-down menu
component that is deployed from a menu bar.
Constructors of Menu Class
| Name |
Description |
Menu() |
This constructor creates instance of a Menu. |
Menu(String text) |
This constructor creates instance of a Menu with the
given label of string |
Menu(String text, boolean tearOff) |
This constructor creates instance of a Label with the
given label of string and also check menu is turn off. |
Methods of Menu Class
| Method |
Description |
add(MenuItem mi) |
This method add menu item in Menu. |
add(String label) |
This method add string at menu. |
addSeparator() |
This method add separator between menu items. |
getItem(int index) |
This method gets the item from the given index. |
getItemCount() |
This method gets the number of item inside the menu. |
insert(MenuItem menu item, int index) |
This method inserts menu item inside menu. |
insertSeparator(int index) |
This method inserts separator between menu item. |
remove(MenuComponent item) |
This method remove menu item from menu. |
remove(int index) |
This method remove menu item from menu as per the index. |
removeAll() |
This method remove all menu item from menu. |
Example :
package com.techknow.menu;
import java.awt.Dimension;
import java.awt.Frame;
import java.awt.Menu;
import java.awt.MenuBar;
import java.awt.MenuItem;
import java.awt.SystemColor;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JOptionPane;
public class MenuDemo extends Frame
{
private MenuBar menuBar1 = new MenuBar();
private Menu menu1 = new Menu("File");
private Menu menu2 = new Menu("Help");
private MenuItem hello=new MenuItem("Hello");
private MenuItem bye=new MenuItem("Bye");
private MenuItem aboutus=new MenuItem("About Us");
public MenuDemo()
{
try
{
jbInit();
}
catch (Exception e)
{
e.printStackTrace();
}
}
private void jbInit() throws Exception
{
this.setLayout( null );
this.setSize( new Dimension( 400, 300 ) );
this.setBackground( SystemColor.control );
this.setVisible(true);
this.setLocation(150,150);
this.setMenuBar(menuBar1);
menu1.setLabel("File");
hello.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
hello_actionPerformed(e);
}
});
bye.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
bye_actionPerformed(e);
}
});
aboutus.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
aboutus_actionPerformed(e);
}
});
menu1.add(hello);
menu1.add(bye);
menu2.add(aboutus);
menuBar1.add(menu1);menuBar1.add(menu2);
}
public static void main(String args[])
{
MenuDemo obj=new MenuDemo();
}
private void hello_actionPerformed(ActionEvent e)
{
JOptionPane.showMessageDialog
(this,"Hello Friends" );
}
private void bye_actionPerformed(ActionEvent e)
{
JOptionPane.showMessageDialog
(this,"Bye Friends" );
System.exit(0);
}
private void aboutus_actionPerformed(ActionEvent e)
{
JOptionPane.showMessageDialog
(this,"Hey Friends this is the
Techknow Heights Examples" );
}
}
Output :
- SubMenu provides easy way of displaying menu items based on
SubMenuModel.
- Each item in a menu must belong to the MenuItem class. It
can be an instance of MenuItem, a submenu (an instance of Menu), or
a check box (an instance of CheckboxMenuItem).
- In AWT creating a SubMenu is easy, you just add menu item
to another menu item.
Example :
package com.techknow.menu;
import java.awt.Dimension;
import java.awt.Frame;
import java.awt.Menu;
import java.awt.MenuBar;
import java.awt.MenuItem;
import java.awt.SystemColor;
public class SubMenuDemo extends Frame
{
private MenuBar menuBar1 = new MenuBar();
private Menu menu1 = new Menu("MenuBar");
private Menu menu2 = new Menu("Menu");
private MenuItem menu3 = new MenuItem("SubMenu");
private MenuItem menu4 = new MenuItem("SubMenu");
private MenuItem menu5 = new MenuItem("SubMenu");
public SubMenuDemo()
{
try
{
jbInit();
}
catch (Exception e)
{
e.printStackTrace();
}
}
private void jbInit() throws Exception
{
this.setLayout( null );
this.setSize( new Dimension( 400, 300 ) );
this.setBackground( SystemColor.control );
this.setLocation(150,150);
this.setVisible(true);
this.setMenuBar(menuBar1);
menuBar1.add(menu1);
menu1.add(menu2);
menu2.add(menu3);
menu2.add(menu4);
menu2.add(menu5);
}
public static void main(String args[])
{
SubMenuDemo obj=new SubMenuDemo();
}
}
Output :
- NestedMenu provides easy way of displaying menu items based
on NestedMenuModel.
- Each menu in a menu must belong to the Menu class.and
futher the nested menu must be belong to the menuItem class .It can
be an instance of MenuItem, a Nestedmenu (an instance of Menu), or
a check box (an instance of CheckboxMenuItem).
- In AWT creating a NestedMenu is easy, you just add menu
item to another menu item.
Example :
package com.techknow.menu;
import java.awt.Dimension;
import java.awt.Frame;
import java.awt.Menu;
import java.awt.MenuBar;
import java.awt.MenuItem;
import java.awt.SystemColor;
public class NestedMenuDemo extends Frame
{
private MenuBar menuBar1 = new MenuBar();
private Menu menu1 = new Menu("MenuBar");
private Menu menu2 = new Menu("Menu");
private MenuItem menu3 = new MenuItem("SubMenu");
private MenuItem menu4 = new MenuItem("SubMenu");
private Menu menu5 = new Menu("SubMenu");
private MenuItem menu6 = new MenuItem("NestedMenu");
private MenuItem menu7 = new MenuItem("NestedMenu");
private MenuItem menu8 = new MenuItem("NestedMenu");
public NestedMenuDemo()
{
try
{
jbInit();
}
catch (Exception e)
{
e.printStackTrace();
}
}
private void jbInit() throws Exception
{
this.setLayout( null );
this.setSize( new Dimension( 400, 300 ) );
this.setBackground( SystemColor.control );
this.setLocation(150,150);
this.setVisible(true);
this.setMenuBar(menuBar1);
menuBar1.add(menu1);
menu1.add(menu2);
menu2.add(menu3);
menu2.add(menu4);
menu2.add(menu5);
menu5.add(menu6);
menu5.add(menu7);
menu5.add(menu8);
}
public static void main(String args[])
{
NestedMenuDemo obj=new NestedMenuDemo();
}
}
Output :
