Microsoft largely cloned the Java Runtime to create the .NET Runtime and similarly cloned Java to create C#. The two are so similar that Java bytecode to .NET

Microsoft largely cloned the Java Runtime to create the .NET Runtime and similarly cloned Java to create C#. The two are so similar that Java bytecode to .NET bytecode translators exist. With some, it is possible to take a class defined in Java, subclass it with C#, call it from Java, etc...