Java Learning (GUI)

JButton component represents a pushing button in SWING package. On the button created by the JButton class, you can place an image and text. This button can generate an action event. There are two ways to receive the action event of the button. One way is using the ActionListener interface. The alternative is using the Action interface. By using AbstractAction class that implements the Action interface, you can only receive the event but also can specify the properties (icon and text) of the button. See the example code below.

Constructors of the JButton class:
 -JButton()
 creates a new button without image or text.
 -JButton(String text)
 creates a new button with text to describe it.
 -JButton(Action action)
 creates a new button with its properties (icon and text) taken from the Action interface implementation.
 -JButton(Icon icon)
 creates a new button with an icon image.
 -JButton(String text,Icon icon)
 creates a new button with text and an icon image.

Useful methods of the JButton class:
 -getText():String
 gets the text of the button.
 -setAction(Action action):void
 sets the Action implementation to the button.
 -setMnemonic(int key):void
 sets the mnemonic key to the button. This key when combined with the mouseless modifier key (usually Alt) will activate the button when it is focused.

 -setText(String text):void
 sets text of the button.

Examples:

By Using Code

import java.awt.Color;
import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.Image;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;

import javax.swing.AbstractAction;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
class JButtonShow extends JFrame {

JButtonShow(String title) {
setTitle(title);
setSize(400, 300);
setLayout(new FlowLayout(FlowLayout.LEFT));
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Container contpane = getContentPane();
contpane.setBackground(Color.WHITE);
Image imgnew = Toolkit.getDefaultToolkit().getImage("FilesNew.png");
JButton btnew = new JButton();
btnew.setAction(new Action("New", new ImageIcon(imgnew)));
btnew.setMnemonic(KeyEvent.VK_N);
Image imgopen = Toolkit.getDefaultToolkit().getImage("Open.png");
JButton btopen = new JButton();
btopen.setAction(new Action("Open", new ImageIcon(imgopen)));
btopen.setMnemonic(KeyEvent.VK_O);
contpane.add(btnew);
contpane.add(btopen);
setVisible(true);
}
class Action extends AbstractAction {
Action(String text, ImageIcon icon) {
super(text, icon);
}
public void actionPerformed(ActionEvent e) {
System.out.println(e.getActionCommand());
}
}
}
public class JButtonClass {
public static void main(String[] args) {
new JButtonShow("JButton");
}
}

JFrame Look Like This

JFrame With JButtons

By Using GUI

Drag & drop JButtons from your Palette and set their following properties,

Drag & Drop JButton in JFrame

• Goto Property Window of JButton Select icon property. 

JButton Property Window

Select icon for JButton

• That's it ,your window look like this

JButton With Icon

JTextField component represents a text field that you can edit a single line of text. Unlike TextField, JTextField allows you to decorate the border of the text field, and specify the color of selected text. JTextField does not support password functionality. If you want password input, you need to use the JPasswordField instead.
The JTextField component can generate document events. A document event can be received by implementing the DocumentListerner interface and registering the listener by invoking the addDocumentListener(DocumentListener listener) method. The DocumentListener interface has three methods: removeUpdate(DocumentEvent e), insertUpdate(DocumentEvent e), and changedUpdate(DocumentEvent e) to be overridden.

Constructors of the JTextField class:
 JTextField()
 creates an empty text field.
 JTextField(int columns)
 creates a text field with specified number of columns.
 JTextField(String text)
 creates a text field with text.
 JTextField(String text,int columns)
 creates a text field with text and specified number of columns.

Useful methods of the JTextField:
 getText():String
 returns the text of the text field.
 setBorder(Border bd):void
 specifies the border of the text field.
 select(int start,int end):void
 selects the text in the text field from start to end positions.
 setSelectionColor(Color c):void
 specifies the color of the selected part.
 setSelectedTextColor(Color c):void
 specifies the selected text color.
 setText(String text):void
 sets text to the text field.

Example:

First of all import this classes

import java.awt.Color;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
import javax.swing.plaf.basic.BasicBorders;

After that goto WindowActivated event and write code like below.

private void formWindowActivated(java.awt.event.WindowEvent evt) {                                     
txtDemo.getDocument().addDocumentListener(new DocumentListener() {
@Override
public void insertUpdate(DocumentEvent e) {
System.out.println("a remove insert fire."); //To change body of generated methods, choose Tools | Templates.
}
@Override
public void removeUpdate(DocumentEvent e) {
System.out.println("a remove Update fire."); //To change body of generated methods, choose Tools | Templates.
}
@Override
public void changedUpdate(DocumentEvent e) {
System.out.println("a change update fire."); //To change body of generated methods, choose Tools | Templates.
}
});
txtDemo.select(0, 10);
txtDemo.setSelectedTextColor(Color.CYAN);
txtDemo.setBorder(new BasicBorders.FieldBorder(Color.BLUE, Color.BLACK, Color.GREEN, Color.LIGHT_GRAY));
}

End of all you window look like this:

JTextField Example

History of Internet

Protocols of Internet

The Internet is the global "Network of Networks," linking thousands of computer networks together.
Because the Internet is a global network of computers each computer connected to the Internet must have a unique address. Internet addresses are in the form xxx.xxx.xxx.xxx where xxx must be a number from 0 - 255. This address is known as an IP (Internet Protocol) address. Below figure 1.1 shows the Internet address.

The above figure shows two computers connected to the Internet; your computer with IP address 1.2.3.4 and another computer with IP address 5.6.7.8. The Internet is represented as an abstract object in-between.
Every computer that is connected to the Internet is part of a network, even the one in your home. For example, you may use a modem and dial a local number to connect to an Internet Service Provider (ISP). At work, you may be part of a local area network (LAN), but you most likely still connect to the Internet using an ISP that your company has contracted with. When you connect to your ISP, you become part of their network. The ISP may then connect to a larger network and become part of their network. So we can say that the Internet is simply a network of networks. Figure 1.2 shows how computer network work.

Most large communications companies have their own dedicated backbones connecting various regions. In each region, the company has a Point of Presence (POP). The POP is a place for local users to access the company's network, often through a local phone number or dedicated line. The amazing thing here is that there is no overall controlling network. Instead, there are several high-level networks connecting to each other through Network Access Points (NAP).
it is an Interconnection of computers and computer networks using TCP/IP communication protocol.

Java

Java

Java