Convert SIS to JAR

A Java ME emulator, Series 40 phone, or preservation workflow may require the original .jar payload from a Symbian installer. This is possible only when the .sis or .sisx package already contains a Java archive; native Symbian software cannot be converted into Java.

What SIS files contain

SIS is the Symbian Installation System package format, used by Nokia and other Symbian devices to install applications, resources, language files, certificates, and installation scripts. .sisx is a later SIS package variant commonly associated with Symbian OS platform-security signing.

A SIS package may hold native Symbian executables, such as E32 images, or it may include Java ME files such as .jar and .jad. Series 60 devices supported both native SIS-installed applications and Java ME MIDlets; Series 40 devices commonly installed Java ME applications from JAR/JAD files rather than SIS packages.

Only extraction is possible. A compiled Symbian C++ application uses Symbian OS APIs and native ARM code, while a JAR contains Java bytecode for a Java runtime. Renaming app.sis to app.jar does not change its format or make it runnable.

What a JAR file provides

JAR is a ZIP-based archive containing Java classes and resources. Java ME applications normally use a JAR, sometimes accompanied by a .jad descriptor; compatible phones and Java ME emulators can install or load this format directly.

A Java ME JAR normally includes META-INF/MANIFEST.MF with fields such as MIDlet-Name, MIDlet-Version, and MIDlet-1. Extracting the original JAR preserves the Java application payload for devices, emulators, inspection, and archiving without retaining the Symbian-specific installer wrapper.

Extracting an embedded JAR

Use SISContents on Windows to inspect and extract files from SIS and SISX packages. The Symbian SDK command-line utility unmakesis, when available with an older SDK installation, is an alternative for extracting a package to a directory.

1. Open the .sis or .sisx file in SISContents.
2. Browse the package file list for entries ending in .jar or .jad.
3. Extract the JAR to a separate folder, retaining its .jar extension. Extract a matching JAD file as well, if present.
4. Validate the extracted archive with a JDK command such as jar tf game.jar. A normal Java archive should list files, including META-INF/MANIFEST.MF and usually .class files.
5. Open META-INF/MANIFEST.MF to confirm that it contains Java ME MIDlet entries if the target is a Java ME phone or emulator.

If an extracted file has no extension, inspect it before renaming it. A ZIP signature and Java classes or a MIDlet manifest support renaming it to .jar; a generic resource archive does not.

No reputable online service can convert an arbitrary SIS application into a working JAR, so there is no online converter to recommend for this task. Avoid upload-based “SIS to JAR” converters: they cannot translate native Symbian code into Java bytecode and may expose proprietary software.

Compatibility limits

If the package contains no JAR, obtain the original Java ME release from the publisher or a trusted software archive. Creating a new JAR requires the application's source code and a Java ME rebuild; decompiling and porting native Symbian code is a software-development project, not file conversion.

An extracted JAR can still fail on the target platform. Java ME MIDlets may require specific CLDC and MIDP versions, Nokia vendor APIs, screen dimensions, network permissions, signed certificates, or an accompanying JAD descriptor. Test the file on the intended phone or in a Java ME emulator configured for the relevant device profile.

A SIS installer can also supply icons, permissions, file placement, and installation logic that are not represented by the embedded JAR. Preserve the original SIS/SISX package alongside the extracted JAR when archiving software.