class files into a single file named Painter.jar: jar cf Painter.jar Painter.class Shape.class Canvas.classThe result is a jar file created: Painter.jarThe following picture illustrates the content of this jar file: Now, you can execute this Java application using the java command with the -jar option: java -jar Painter.jarType jar -help to see all available options for this tool.For full syntax description, check the following official documentation from Oracle: class files: Painter.class, Shape.class and Canvas.classThen type the following command to put all these. It consists of 3 classes: Painter.java, Shape.java, and Canvas.javaUsing the javac tool, you compile these. class files) to make deployments of Java libraries and applications in jar files.For example, suppose that you did write a painter program in Java.
In turn, the JVM loads and runs the application bundled in that jar file.As a Java programmer, you need to understand and be able to use the jar tool for packaging your compiled code (. When you double click the jar file, the operating system is triggered to start the JVM. junit.jar, log4.jar, MyProgram.jar, etc.You can think that a jar file is the executable of a Java application, like the. class files.Therefore, Java applications and libraries are packed in.
jar file is actually a Zip file that contains all the.
class files into a single unit for easy deployment and execution. This tool is used for putting a group of related.
It is the Java Archive tool - hence the jar name for its executable file.Typically, jar is one of the tools that participate in the process of building a Java application, as shown in the following picture: jar is a command-line tool just like javac and java. The Java archive toolBesides javac and java, there’s another one in JDK which is also an important tool in Java programming. Like a pilot has to experience thousands hours of flight in order to completely control the airplane.Good news is that you can go faster with my experiences compiled into the following articles with practical examples:Ģ. You cannot master them in just 1 or 2 days. Of course there are parameters and options which you can find by typing javac -help or java -help.Here are the official documentations for these tools:Ĭertainly it takes time and effort to control these tools. Here are the typical steps to compile and run a Java program whose source file is HelloWorld.java: All editors or IDEs rely on these tools for compiling and executing Java applications. javac and java are the cornerstones of the Java programming language. class file, verifies the bytecode and executes it. Missing one, the airplane cannot flight properly.Technically, javac is the program that translates Java code into bytecode (.class file) - an intermediate format which is understandable by the Java Virtual Machine (JVM).And java is the program that starts the JVM, which in turn, loads the. Without engines, the airplane cannot take off. The following picture illustrates this process: You can imagine that the javac and java are two engines of an airplane. java) and calls the Java launcher ( java.exe) to run the compiled files (.class). Java compiler and Java application launcherWhen you are using an editor or an IDE (Integrated Development Environment) like Sublime or NetBeans to develop Java applications, the editor/IDE invokes the java compiler ( javac.exe) to compile the source files (. This article gives you an overview about these 3 key tools in Java development. In the Java Development Kit (JDK), there are three tools which can be used in conjunction to develop Java applications.