Primitive Types

There are two kinds of primitive data types supported by the JVM; numeric types and the returnAddress type.

The numeric types consist of the integral types :

• byte, 8-bit signed two's-complement integers;

• short, 16-bit signed two's-complement integers;

• int, 32-bit signed two's-complement integers;

• long, 64-bit signed two's-complement integers;

• char, 16-bit unsigned integers representing Unicode version 1.1.5 characters.

and the floating-point types :

• float, 32-bit IEEE 754 floating-point numbers;

• double, 64-bit IEEE 754 floating-point numbers.

Operations on values of a numeric type include arithmetic operations, comparison operations and conversion operations.

The values of the returnAddress type are pointers to the opcodes of JVM instructions, and it is not a Java language type like the numeric primitive types. There are no operations on values of the returnAddress type. This type is used by the JVM instructions jsr, jsr_w and ret, which jump to and return from a subroutine using a value of the returnAddress type to save the address of the instruction to return to after the subroutine.

There is no boolean type; operations on booleans are compiled to use the int data type to represent boolean values.