The Java.lang.Void class is a placeholder, if it represents the void keyword, it holds a reference to the class object. It is a placeholder that cannot be instantiated. Well, non-instantiable means that this class has a private constructor, and there is no other constructor that we can access from the outside.

In Java, java.lang.Void is a special class that represents the void keyword, which is used to indicate that a method does not return any value. The Void class is a part of the Java standard library and is located in the java.lang package.

Java is a popular programming language that is widely used in software development. One of its key features is the ability to manipulate different data types, including integers, characters, and floating-point numbers. One of the data types that Java supports is the "long" data type, which is used to store 64-bit integers.

The "java.lang.Long" class is a part of the Java standard library and provides several methods for working with long integers. One of these methods is the "reverse" method, which is used to reverse the order of the bits in a long integer.

The "reverse" method works by swapping the bits in the long integer. It takes a long integer as its argument and returns a long integer with the bits reversed. For example, if the input long integer is "0b1010", which is equivalent to the decimal value 10, the output of the "reverse" method would be "0b0101", which is equivalent to the decimal value 5.

Here is an example of how to use the "reverse" method in Java: 

long num = 12345;
long reversedNum = Long.reverse(num);
System.out.println("Original number: " + num);
System.out.println("Reversed number: " + reversedNum);

This code will output the following: 

Original number: 12345
Reversed number: -7613618672022844416

As you can see, the "reverse" method has successfully reversed the order of the bits in the original long integer.