To sign a Java applet, follow these steps: Compile your applet with `javac` Create a jar file with `jar` Generate a keystore database with `keytool` Sign the jar file with `jarsigner` Export the public key certificate with `keytool’

A Java decompiler is a special type of decompiler which takes a class file as input and produces Java source code as output. Java Decompilers Jode JODE is a Java package containing a decompiler and an optimizer for java. This package is freely available under the GNU GPL. The bytecode package and the core decompiler is now under GNU Lesser General Public License, so you can integrate it in your project. The Jode Java decompiler reads in class files and produces something similar to the original java file. Of course Read More

The Java Virtual Machine (JVM) is a collection of software programs and data modules that forms part of the Java and Java 2 platforms. JVM works across all platforms and it alters Java bytecode into machine understandable code and executes it. It acts as a clone of a Java processor allowing Java bytecode to be implemented as an action or as a system call. JVM is a vital building block of the Java platform, as it enables Java code or applications to be executed across platforms. The JVM recognizes and Read More

The JDK ships with jdb, the Java Debugger. JSwat is a better way to debug Java. JSwat is a graphical Java debugger front-end which is licensed under the GPL. Patricia Sherman has written an excellent tutorial on debugging Java, titled Debug Strategy.

JAR is an abbreviation for Java Archive. It is basically a file in archive format used to group and integrate Java classes, resources, metadata together which can then be easily distributed across Java platform. However the underlying file format is ZIP with a .jar extension. Every JAR file contains a manifest file which is normally the first in the JAR header. The Java Development Kit (JDK) bundles an built-in tool to create and extract JAR files.  Like any archive format, JAR also helps compress data that’s packed into it. The Read More

Java source code is code that you write in the Java programming language. Java source code is converted to Java bytecode by the Java compiler. Java source code files usually have the .java extension. Sun recommends that Java source code files be no longer than two thousand lines. Larger source code files should be split up into multiple smaller files.

“cannot resolve symbol” means that the Java compiler cannot locate a symbol referenced in your Java source code. The causes for this common error include: A missing class file A faulty CLASSPATH A symbol name is mispelled or miscapitalized A data type is incorrect, misspelled, or miscapitalized A method is called with the wrong number or types of arguments An undeclared variable cannot resolve symbol errors can be very difficult to track down. Code carefully!

Inheritance is what happens when a subclass receives variables or methods from a superclass. It is also when one class passes down its properties to another class. The main reason for inheritance is reusability. Distinguishing a new class from an existing class is called derivation. The old class is referred to as the base class and the new class is called a derived class or sub class. The derived class inherits some or all of the traits from the base class. A class can also inherit properties from more than Read More

JavaScript is a programming language and interactive web platform that allows users to interact with a webpage in a variety of different ways. For example, JavaScript can be used to create interactive drop-down navigation menus in a webpage, insert expandable content into forms or tables, and create interactive slideshows. JavaScript can also be used to create browser-based flash games and applications for a variety of platforms. How JavaScript Works JavaScript is a trademark of the Oracle Corporation and is similar to the programming language, “C”. JavaScript is designed to provide Read More

Many applications require the Java Runtime Environment (JRE) to run. The JRE must be downloaded and installed on each PC where you intend to run Java-based applications. Steps to Install Java on Microsoft Windows Go to the Java Software Download Page Select the proper version of Java for your computer Click the download button Click run Click run Check I accept the terms in the license agreement Click next Click next Click finish Click yes to restart Windows now or no to restart Windows later