In java, int, byte and boolean are primitives, while String is not.

This can be contrasted with c where string is a primitive (essentially an array of chars).

What is the term for types that aren't primitive?


2 Answers 2


The most general term (language agnostic) is a composite data type.

In Java there are several types of composite data type, the most obvious is a Class but an Enum would be another example.

A boxed type is another related term, which is a primitive wrapped in a class to provide an object oriented interface. Examples of this in Java are an int vs. an Integer or a char vs. a Character.

In java, int, byte and boolean are primitives, while String is not.

A String is actually a boxed type. Under the hood it's implemented as a char array just like C and you could use a char array too if you wanted. Obviously most people don't do this as you won't have any of the convenient abstractions provided by the String class.

Here's how the java.lang.String class is implemented in openjdk:

/** The value is used for character storage. */
private final char value[];

As you can see, there's nothing special about a string in Java.

  • 2
    Depending on the language, there may be abstract non-primitive datatypes that aren't composite (the implementation uses a primitive type, but the type system ensures you can't rely on that.) Additionally, wrapped primitive types are only "composite" in a rather degenerate way. The best way to describe the opposite is primitive is probably just "non-primitive", or perhaps "user-defined".
    – Doval
    Apr 9, 2015 at 11:39
  • I don't think you can consider String a boxed type, since the underlying character array is actually a reference type. In C# though you can consider it a boxes type, I believe, because it wraps a pointer to a character array.
    – Sebazzz
    Apr 15, 2015 at 15:07

Composite Data Types (CDTs)

One answer to this question may be CDTs, but I don't think that is a general enough response. CDTs only account for a subset of non-primitive types: the definition of CDTs does not account for types that include methods. In fact, CDT is further misleading as they are expected to aggregate data, i.e., include fields. It is not a requirement for non-primitives to have fields.

User Defined Types (UDT)

There are ample examples of non-primitive non-UDTs, e.g., String in Java.

Reference Types

This doesn't help either. Consider that a pointer in C may point to anything, including primitive types.


As far as I am aware there is no general term for non-primitive types. Maybe except, as mentioned by @Doval, "non-primitive type".

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.