Can't execute jar- file: "no main manifest attribute"

The "no main manifest attribute" error is usually caused by a missing or incorrect Main-Class attribute in the manifest file of a Java .jar file.

To fix this error, you need to ensure that the .jar file has a valid MANIFEST.MF file with a correctly defined Main-Class attribute. The Main-Class attribute specifies the class that contains the main method, which is the entry point for the application.

Here is an example of a valid MANIFEST.MF file with a Main-Class attribute:

Manifest-Version: 1.0
Main-Class: com.example.MyClass

To create a .jar file with a MANIFEST.MF file, you can use the jar tool that comes with the JDK (Java Development Kit). Here is an example of how to create a .jar file with the jar tool:

jar cfm MyJarFile.jar com/example/*.class

This command creates a .jar file called MyJarFile.jar that includes the file and all the .class files in the com/example directory.

I hope this helps. Let me know if you have any questions.