How to Schedule a Shutdown in Java - Java Code to Schedule a Shutdown

In this post, we will see how to schedule a shutdown in a computer using java program. For this, we execute the appropriate shutdown command after identifying the operating system. The following java code will schedule a shutdown after a 10 minute from execution of the code.

String os=System.getProperty("os.name").toLowerCase();
String command;
try
{
if(os.contains("windows"))
    {
    command="shutdown /s /t 600";
    }
else if(os.contains("linux")||os.contains("mac os x"))
    {
    command="shutdown -h +600";
    }
else
    throw new Exception("Unsupported OS");
Runtime.getRuntime().exec(command);
}catch(Exception ex){
JOptionPane.showMessageDialog(null,ex.getMessage());
}

How to Logoff or Sign Out Windows Using Java Code

You can sign out the current user account from windows using java code. Sign out, log out or logoff button can be created using simple lines of code. To logout from Windows operating system using java code, use the following code:

try {
        Runtime.getRuntime().exec("shutdown /l");
    } catch (IOException ex) {}

As the above code shows, we are simply executing a cmd command shutdown /l. It is actually running shutdown.exe with parameter /l to force logoff. If you add above code in the actionPerformed() function of a button, the button becomes a logoff button. The following video will show an example in which a simple button is made into a logout button.

Java Program to Send a File over a Network after Encryption

Here is a simple java program which can be used to send and receive encrypted files over network. The sender encrypts the file before sending and the receiver decrypts the file and displays it. The program is based on a networking lab experiment at my college. So, although we say 'encryption', characters are simply incremented here. The lab question was as follows:

A client wants a file that is with a server in a secure system. The server encrypts the file in such a way that 'A' will be replaced with 'B', 'B' with 'C'... and 'Z' with 'A' and sends to the client. The client should get file and decrypt it to the original one and display the content. Implement it using TCP/IP.

How to Load a Webpage in a Java App

Do you wonder how to load a webpage in your java application? It is simple. You can load a web document whether it is a web document in internet or a web document from a file in the localhost. I know three methods to do it. You can use JTextPane in java swing (javax.swing), JEditorPane in java swing (javax.swing) or WebView in javaFX (javafx.scene.web.WebView). We will discuss each method to display a webpage in a java application.

The three methods we are going to discuss are:

• Using JTextPane
• Using JEditorPane
• Using WebView in JavaFX

How to Get User Related Informations in Java

In java, there are some methods that will help you to know some user related informations. Here also,

System.getProperty() 

method can give some informations about the user like:

User account name
User Working directory
User Home directory

To get the username of current user on the computer just call

System.getProperty("user.name")

It will return the current username as a string.

To get the working directory of current user on the computer call

System.getProperty("user.dir")

It will return the path of working directory of current user as a string.

To get the home directory (user's home folder) of current user on the computer call

System.getProperty("user.home")

It will return the path to home directory (folder) of current user as a string.

How to Get Center Point of Screen in Java

If you want position your JFrame in center of screen, there is method for that. Read this post:

How to Set JFrame in Center of Screen

The LocalGraphicsEnvironment in Java will give you the center point of the display or screen. There is a static method getLocalGraphicsEnvironment() in GraphicsEnvironment class. To get the center point of the screen, you may use the following java code:

Point centre=GraphicsEnvironment.getLocalGraphicsEnvironment().getCenterPoint();

You should include these import statements in the file.

import java.awt.Point; import java.awt.GraphicsEnvironment;

How to Change Look and Feel of a Java Application

The following code fragment which can be used within main method or in constructor of the class tells you how to change the look and feel of a java program (java application). This sample code sets the LookAndFeel of the java application into Windows Look and Feel.

TCP Server Client Two Person Chat Program in Java with GUI

Server-Client chat program or two way chat using TCP connection is a common problem for java practical labs or networking labs. Here this post introduces a simple lightweight Server client two person chat program using java. The program uses ServerSocket and Socket classes available in java.net package. This program is written so as to use the same as server or as client. Both the persons who chat use the same program. One should select hosting (acting as server) while the other could connect to him by entering the server ip address. I have added screenshots of the program also.
See Screenshots

Clock Application using Java - Java Source Code for Analog Clock Application

For my java practical lab experiments, i had to create an analog clock using java. So, i created a

Analog Clock Application using Java.

simple analog clock using java. The program source code is added below. It makes use of java 2D Graphics Object and draws the clock in the screen. The clock displays all the three hands (hour hand, second hand and minute hand). The program source code is as follows. The screenshot of the java analog clock application is also added.

How to Remove Title bar from JFrame of Java Application

To remove the title bar completely, there is a method called setUndecorated() in java. It takes a boolean variable. If the boolean is true, the title bar will be removed. The following one is an example. The method setUndecorated() invoked with a true boolean argument, will remove the title bar from the JFrame MyJFrame. The method is called here from the constructor. You may call it anywhere from within the class scope.

How to Change Image in JButton in Java - Set Icon of JButton

In this post we are discussing how to change the image in button in Java. There may be situations in

Jbutton with Image set

programming where we want to know how to set JButton image in java or to change button icon in java. The java code to change the icon of a Jbutton is so short. We use the

setIcon()

method in JButton class. The setIcon method takes an ImageIcon object as an argument. I will show you a sample java code in which the icon of  button is set. First of all,  you have to copy the icon image (jpg, bmp, png or gif image) to the src folder in the project directory. You may also place it in some folder inside the src folder. If you are using netbeans IDE, you can simply drag and drop the image file into the desired folder in the projects pane. After copying the icon image to src folder (or any subfolder in it), use the following code to set it as the button's icon.

playbtn.setIcon(new ImageIcon(getClass().getResource("/manhaj/images/play.png")));