CPIO to JAR Converter

JAR (Java Archive) is a package file format based on ZIP, developed by Sun Microsystems) and introduced with JDK 1.1 in January 1996 for distributing Java class files, associated metadata, and resources as a single deployable unit. A JAR file is structurally a ZIP archive with an added META-INF/MANIFEST.MF file — a text manifest that declares the archive's main class entry point, classpath dependencies, package versioning, and digital signature information. The Java runtime loads classes directly from JAR files without extraction, using the ZIP directory for efficient random access to individual entries. JAR archives can be made executable: specifying a Main-Class attribute in the manifest allows launching the application with a simple java -jar command. The format supports code signing through the JDK's jarsigner tool, embedding digital signatures that verify the authenticity and integrity of the archive's contents. One advantage is the Java ecosystem's native integration — the JVM, build tools (Maven, Gradle), application servers, and IDEs all treat JAR files as first-class artifacts, enabling a unified build-deploy-run pipeline. The format's backward compatibility with standard ZIP) tools is another practical strength: any ZIP utility can inspect JAR contents, while the manifest and signing layers add Java-specific capabilities on top. JAR remains the fundamental distribution unit for Java libraries and applications across enterprise, mobile, and embedded deployments.