What data types exist in the context of JVM?

In the context of JVM, there are two types of data: primitive types and reference types.

Primitive Types:

• Represent basic values (numbers, characters, boolean values).
• The size and range of these types are strictly defined by the JVM specification.
• Passed by value.
• Stored in the stack.

List of primitive types:

• boolean: true or false.
• byte: 8-bit signed integer.
• short: 16-bit signed integer.
• char: 16-bit Unicode character (unsigned).
• int: 32-bit signed integer.
• long: 64-bit signed integer.
• float: 32-bit single-precision floating point.
• double: 64-bit double-precision floating point.

Reference Types:

• Represent references (addresses) to objects in memory (Heap).
• The size of references usually depends on the JVM architecture (32-bit or 64-bit).
• Passed by reference (reference passing), although technically a copy of the reference itself is passed.
• Stored in the heap.

Types of reference types:

• Class Types: Instances of user-defined or library classes (e.g., String, Object).
• Interface Types: References to objects implementing a specific interface.
• Array Types: Container objects for storing ordered collections of elements (both primitive and reference types).

Example usage:

// Primitive type
int primitiveInt = 10;

// Reference type (String object)
String referenceString = new String("Hello");

// Primitive type in array
int[] primitiveArray = {1, 2, 3};

// Reference type in array
String[] referenceArray = {"A", "B"};