How do I reengineer a JAR file?

How do I reengineer a JAR file?

2 Answers

1. Use JD-GUI to examine the jar file.
2. Unpack the jar file. jar -xf yourapp.jar.
3. Modify the .class file with a Java Bytecode Editor. Use Java Bytecode Editor (JBE)
4. Repack the modified classes into new archive file. jar -cvf yourapp_patched.jar *.*

How do I import a JAR file?

Your answer

1. Right click on your project.
2. Select Build Path.
3. Click on Configure Build Path.
4. Click on Libraries and select Add External JARs.
5. Select the jar file from the required folder.
6. Click and Apply and Ok.

How do you find the main class in a jar?

Technically a jar file can contain more than one main class. When java executes a jar file, it looks in the META-INF/MANIFEST. MF file inside the jar to find the entrypoint. There is no direct command to get this information, but you can unpack the jar (it’s just a zip file) and look into the manifest yourself.

How do you edit and recompile a jar file?

3 Answers

1. add the jar as a dependency to that project.
2. Create a new class named ScreenCapture.
3. copy the whole source from your JD too view the screenshot of which u attached here.
4. change the code which u want.
5. build the project.
6. check the bin folder of you eclipse project .
7. open the jar in winrar and copy the .

Can jar files be decompiled?

Unless you explicitly packaged your source code in the JAR file, there’s no way to get back the original source. You could try using a decompiler (like this) but that will hardly give you nice, readable code. The best solution would be to stop using your computer right now.

How to import classes from.jar files in Java?

Not every jar file is executable. Now, you need to import the classes, which are there under the jar, in your java file. For example, import org.xml.sax.SAXException;

How to print class names from Jar file?

Using the jar command to print the class names from a JAR file is pretty straightforward. However, sometimes we want to load some classes from a JAR file in our Java program. In this case, the command-line output isn’t enough. To achieve our objective, we need to scan the JAR file from a Java program and get the class names.

How to execute Java program from.jar file?

However, it’s much better idea to package your program in a jarfile, and include all the required jars within that. Then, in order to execute your jar, like, java -jar my_program.jar you should have a META-INF/MANIFEST.MFfile in your jar.

How do I save a.jar file in Java?

Drag and drop the jar or open .jar file for which you want the sources on the JD. Java Decompiler will open with all the package structure in a tree format. Click on File menu and select save jar sources. It will save the sources as a zip with the same name as the jar.