What is Jar File?
A Jar file is a package file format used to aggregate multiple Java class files and associated metadata and resources (such as images and text files) into a single file. The name “JAR” stands for “Java Archive”.
Jar files are used for a variety of purposes, such as distribution of libraries, applications, and applets. They are commonly used for distributing Java libraries, as they allow developers to package all the necessary files and dependencies into a single file, making it easier for other developers to use the library in their own projects.
Jar files can be created using the “jar” command-line utility that comes with the Java Development Kit (JDK), or using an integrated development environment (IDE) such as Eclipse or IntelliJ IDEA. Jar files can also be extracted and manipulated using various tools, such as the “jar” command-line utility or GUI-based archive managers like WinZip or 7-Zip.
How To Import A Jar File In Eclipse?
To import a Jar file in Eclipse, follow these steps:
- In the Eclipse IDE, create a new Java project or open an existing one.
- Right-click on the project folder in the Package Explorer view and select “Properties” from the context menu.
- In the Properties dialog, select “Java Build Path” from the list on the left.
- Click on the “Libraries” tab in the main panel, then click the “Add External JARs” button.
- Navigate to the location of the JAR file on your file system and select it.
- Click “OK” to close the JAR Selection dialog and “OK” again to close the Properties dialog.
- The JAR file will now be added to the project’s classpath and you can begin using its classes in your code.
Note that the above steps assume that you have the JAR file already downloaded on your local system. If you need to download the JAR file from a remote location, you can also use the “Add External JARs” option in step 4 to add the JAR file directly from its URL.
How To Run A Jar File In Eclipse?
To run a JAR file in Eclipse, follow these steps:
- In the Eclipse IDE, create a new Java project or open an existing one.
- Right-click on the project folder in the Package Explorer view and select “New” from the context menu.
- Select “File” from the sub-menu to create a new file.
- In the “New File” dialog, enter a file name with a “.java” extension (e.g. “MyMainClass.java”) and click “Finish” to create the file.
- In the editor for the new Java file, enter the code for your main class. This should include a main method that will be executed when the JAR file is run.
- Once your code is complete, right-click on the Java file in the Package Explorer view and select “Export” from the context menu.
- In the “Export” dialog, expand the “Java” folder and select “Runnable JAR file”. Click “Next” to proceed.
- In the “Runnable JAR File Export” dialog, select your main class from the “Launch configuration” drop-down menu. Choose a destination and file name for your JAR file.
- Choose the appropriate “Library handling” option for your project, and click “Finish” to export the JAR file.
- To run the JAR file, open a command prompt or terminal window and navigate to the directory containing the JAR file. Type “java -jar myjarfile.jar” (replacing “myjarfile.jar” with the actual name of your JAR file) and press Enter.
Alternatively, you can run the JAR file directly from within Eclipse by selecting “Run As” from the context menu of the JAR file in the Package Explorer view and choosing “Java Application”. This will execute the main method of your main class within the Eclipse environment.