Java jar manifest file

It is good to know which jar files are in my classpath, but after I determine that I have to USE the jar that was found. I might need a little more explanation.

Is the problem that you have the same class which might exist in two different JAR files both in your classpath? In that case, it might be tricky to pick between them. If you have two JAR files and want to pick the source for your class, better to search for them yourself using File functions, then create your own class loader.

Do you want an example of that? I have some code lying around somewhere. You can dynamically load JAR files that are not in your classpath. Method; import java. SimpleDateFormat; import java.

Output is sent to System. This is NOT a dependency, however. The only way to get one is to use this. LogManager" ; if x! Chris Chris. Sign up or log in Sign up using Google. Sign up using Facebook. This lesson will explain the contents of the manifest file and show you how to work with it, with examples for the basic features: Understanding the Default Manifest When you create a JAR file, a default manifest is created automatically.

Modifying a Manifest File This section shows you the basic method of modifying a manifest file. Setting an Application's Entry Point This section describes how to use the Main-Class header in the manifest file to set an application's entry point. Setting Package Version Information This section describes how to use the package version headers in the manifest file.

Enhancing Security with Manifest Attributes This section describes how to use manifest attributes to increase the security of an applet or Java Web Start application.

Another use of the Class-Path attribute is to generate an index of all packages using the option i of the jar tool. The following command will generate an index for all packages in all JAR files listed in the Class-Path attribute of the manifest file in the test.

Sealing a package in a JAR file means that all classes declared in that package must be archived in the same JAR file. The value for the Name attribute is the name of the package and the Sealed attribute has value as true. The following entries in a manifest file will seal a package named com. By default, all packages in a JAR file are not sealed. If you want to seal the JAR file itself, you can include a Sealed attributed, as shown:.

However, you can override it by not sealing a package individually. The manifest file contains information about the JAR file and its entries. A manifest file must end with a new line. The following is a sample manifest file: Manifest-Version: 1. As a synopsis and preview of some of the topics to be covered in this section, the following table summarizes common JAR file operations:. This section shows you how to perform the most common JAR-file operations, with examples for each of the basic features:.

You can use the Jar tool to unpack a JAR file.