How do variable declaration and usage differ in Java and Kotlin?

In Java, variables are declared with a specified type and can be mutable (regular variables) or constants (using the final keyword). For example:

int number = 10;
final String NAME = "John";

In Kotlin, variables are declared using the keywords var and val:

• var — mutable variable
• val — immutable (constant after initialization)

The type can be explicitly specified, but Kotlin often infers it automatically:

var number: Int = 10
val name = "John"

Main differences:

• Kotlin has built-in support for immutable variables through val, promoting safer code.
• Kotlin allows omitting the type if it is obvious from the context (type inference).
• In Java, specifying the type is mandatory.
• Kotlin variables can be declared inside functions and classes with concise syntax.

Thus, Kotlin makes variable declaration more concise and safer, encouraging the use of immutable values.