Get in touch
java-keywords-use
abstract – Used to declare a class or method as abstract (i.e., incomplete, to be implemented by subclass).
assert – Used to test assumptions in code; throws error if condition is false (mainly for debugging).
boolean – Primitive data type that holds true or false.
break – Exits from a loop or switch block.
byte – Primitive data type (8-bit signed integer).
case – Defines individual conditions inside a switch statement.
catch – Used to catch exceptions from a try block.
char – Primitive data type (16-bit Unicode character).
class – Used to declare a class.
const – Reserved keyword, not used in Java.
continue – Skips the current iteration in loops and jumps to the next.
default – Defines the default block in a switch or default method implementation in interfaces.
do – Starts a do-while loop.
double – Primitive data type for 64-bit decimal values.
else – Executes block when if condition is false.
enum – Introduced in Java 5 to define a fixed set of constants.
extends – Indicates inheritance (class or interface extension).
final – Used to declare constants, prevent method overriding or inheritance.
finally – Block that always executes after try-catch.
float – Primitive data type for 32-bit decimal values.
for – Loop construct for iteration.
goto – Reserved keyword, not implemented.
if – Executes block based on condition.
implements – Declares that a class implements an interface.
import – Imports classes or packages.
instanceof – Checks if an object is an instance of a class.
int – Primitive data type (32-bit signed integer).
interface – Defines an abstract type with method signatures.
long – Primitive data type (64-bit signed integer).
native – Indicates method is implemented in native code (e.g., C/C++).
new – Creates new objects.
package – Defines the package of a class.
private – Access modifier: only within the class.
protected – Access modifier: class, package, and subclass.
public – Access modifier: accessible from everywhere.
return – Returns a value from a method.
short – Primitive data type (16-bit signed integer).
static – Defines class-level fields or methods.
strictfp – Ensures consistent floating-point calculations across platforms.
super – Refers to superclass constructor or methods.
switch – Allows multi-branch conditional execution.
synchronized – Ensures only one thread can execute a block/method at a time.
this – Refers to the current object.
throw – Throws an exception.
throws – Declares exceptions a method can throw.
transient – Prevents serialization of a field.
try – Defines block to test code for exceptions.
void – Declares that a method does not return anything.
volatile – Ensures changes to a variable are visible to all threads.
while – Starts a while loop.
✅ Next: Java 6 & 7
No new keywords were introduced in Java 6 or Java 7. Only new features (like try-with-resources, strings in switch, etc.) — but no new reserved words.
Java 8 introduced major features like lambdas and streams, but no new keywords were added.
👉 Functional interfaces, :: method references, -> lambda syntax — all added, but these are not reserved keywords.
Java 9 (2017): Modules introduced (module-info.java) — but no new keywords.
Java 10–12: Added features like var (in Java 10), but let’s break it down below.
var – Introduced for local variable type inference.
Example: var name = "Nitesh";
Java infers that name is of type String.
Java 11: Introduced enhancements like var in lambda parameters, HttpClient, etc.
Java 12: Switch expression preview — no new keywords, just syntax improvements.
Java 14 introduced:
record (preview) — not yet a keyword.
Pattern matching (preview)
These were not keywords yet — just preview features.
sealed – Used to restrict class inheritance.
Example: public sealed class Shape permits Circle, Square {}
permits – Used with sealed classes to specify which classes can extend them.
Example: sealed class A permits B, C {}
record – Became a full keyword in Java 16. Used to declare data-carrying immutable classes.
Example: record User(String name, int age) {}
Java 17 was a Long Term Support (LTS) release.
Many preview features like pattern matching improved — but no new keywords added.
This release focused on incubation features, performance, and simple web server — no keyword changes.
non-sealed – Used to opt-out of sealing in a class hierarchy.
Example:
Became a preview feature here and finalized in Java 21.
Features like record patterns and scoped values were previewed, but no new keywords added.
Java 21 finalized many keywords introduced in earlier previews:
sealed – Finalized.
permits – Finalized.
non-sealed – Finalized.
These keywords are now part of the official Java syntax.
In total, Java 21 has 57 reserved keywords:
From Java 1.0 – 50 core keywords
Java 5 – enum
Java 10 – var
Java 15 – sealed
Java 16 – record, permits
Java 21 – non-sealed (finalized)
Your email address will not be published. Required fields are marked *
