How to Get Class Path in a Java Application

Class Path is the Path used to find directories and JAR archives containing class files. Elements of the class path are separated by platform-specific characters. To get class path from a running java application, you may use the getProperty() method in System class. The following java code will show you how to get class path in java.

String classpath=System.getProperty("java.class.path");
System.out.println("Class path="+ classpath);

Java Program to Send Image between Computers using UDP and Display it

Java program to send image file over network using UDP

This was one of my experiments in Networking Lab. The aim was to write a java program to send a
picture (image) from a computer to another via network using UDP protocol and to display it at the receiving end. Simply, this is the java code to make a java application which can send images from one computer to another over a network. The program uses UDP (User Datagram Protocol). For both the computers (on either ends) the same code is enough. This app can act as a image sender or a receiver. The program uses a Progress bar (JProgressBar) to show the progress of the data transfer. Remember, transferring files over UDP is not easy because UDP does not guarantee ordered delivery, and not even successful delivery. So, here in this program, to ensure ordered delivery, the sender sends next chunk of data (DatagramPacket) only after receiving an acknowledgement for last sent packet. For acknowledgement, i used a string "ACK".

How to Set Background Color of a JFrame in Java

It is easy to set Background color of a JFrame in java. But still many people cannot do it (me too was once like this). Most such people may have tried this java code to set java JFrame background color: setBackground(Color.BLACK);. But this won't work. Instead, you should set the background color of the ContentPane of the JFrame. So, use the following code to set Background color of Frame in your Java Application.

getContentPane().setBackground(Color.BLACK);

or

getContentPane().setBackground(new Color(34,172,176));

Keep in mind that you have to import java.awt.Color; You can use the first one if you don't know RGB values of the desired color. Most common colors are defined as constants in Font class. If you know the RGB color values for your desired color, you can use the second example.

Simple Java Calculator Program Using Java Applet

Screenshot of Simple calculator applet in java

This post shows a sample Calculator Program using Java Applet. This program uses the JApplet Class and Swing components in the program. The full source code is given below. This is a java Applet program for a simple calculator with operations addition, subtraction, division and multiplication on floating point numbers. It also have the C (clear) button. This Java Calculator applet was created by myself for my practical lab experiment. I think this may be useful for beginners in java.