Which of the following is NOT a primitive type in Java?

• A. Integer
• B. Boolean
• C. Char
• D. Double

Answer: (A)

In Java, primitive types are the basic data types that are not objects and are predefined by the language itself. These include boolean, char, byte, short, int, long, float, and double. Each of these types is directly supported by the Java language and represents simple values.

The option identified here as not being a primitive type is Integer. This type is actually a wrapper class in Java that belongs to the java.lang package. Wrapper classes are used to provide object methods for primitive types, allowing them to be treated as objects. For example, with Integer, you can leverage methods such as parsing a string to an integer or converting an integer to a string, which are functionalities that are not available to the primitive int type.

On the other hand, boolean, char, and double are indeed primitive types. Boolean represents true or false values, char represents single 16-bit Unicode characters, and double is a double-precision 64-bit floating point. Each of these types is fundamental and built into the language, distinguishing them from the wrapper classes like Integer.