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Java Keywords

Last Updated : 16 Oct, 2026

Java keywords are reserved words with predefined meanings used by the compiler to perform specific operations. They are part of the language syntax and cannot be modified.

Keywords cannot be used as identifiers (variable, method, class, or object names).
Examples include int, class, if, return, etc.

Java

class Geeks {
    
    public static void main(String[] args)
    {
      	// Using final and int keyword
        final int x = 10;
      
      	// Using if and else keywords
      	if(x > 10){
           System.out.println("Failed");
        }
      	else {
           System.out.println("Successful demonstration"
                              +" of keywords.");
        }
    }
}

Output

Successful demonstration of keywords.

Hierarchy of Keywords

The following diagram represents the classification of Java keywords, including reserved keywords and contextual keywords. true, false, and null are literals, not keywords.

What Happens if we use a Variable Name same as keyword?

Using a keyword as a variable name would give error as shown below.

Java

class Geeks 
{
    public static void main(String[] args)
    {
        String this = "Hello World!";
        System.out.println(this);
    }
}

Output:

./Geeks.java:5: error: not a statement
        String this = "Hello World!";
        ^
./Geeks.java:5: error: ';' expected
        String this = "Hello World!";      
2 errors

Important Points:

The keywords const and goto are reserved, even though they are not currently used in Java.
true, false, and null look like keywords, but in actuality they are literals. However, they still can't be used as identifiers in a program.
In Java, keywords are case-sensitive, and writing Java keywords in upper case (like IF instead of if) will throw an error.

Java Keywords List (As of Java 26)

Java keywords are reserved words that have predefined meanings in the language. They cannot be used as identifiers (like variable or method names). Java SE 26 defines 51 reserved keywords and 17 contextual keywords. Reserved keywords cannot be used as identifiers , while contextual keywords are interpreted as keywords only in specific contexts.

Data Type Keywords

Used to define variable types and specify the kind of data they can hold.

Keyword	Usage
boolean	Defines a variable that holds `true` or `false`.
byte	Defines an 8-bit signed integer.
char	Defines a 16-bit Unicode character.
short	Defines a 16-bit signed integer.
int	Defines a 32-bit signed integer.
long	Defines a 64-bit signed integer.
float	Defines a 32-bit floating-point number.
double	Defines a 64-bit floating-point number.
void	Specifies that a method does not return any value.

Control Flow Keywords

Used to control the execution flow of a program, including loops, branching, and jumps.

Keyword	Usage
if	Executes code when a condition is true.
else	Defines an alternate block when an `if` condition is false.
switch	Selects one block of code among multiple options.
case	Defines an individual branch in a `switch` statement.
default	Defines the block executed if no case matches.
for	Starts a `for` loop.
while	Starts a `while` loop.
do	Starts a `do-while` loop.
break	Terminates the nearest loop or `switch`.
continue	Skips to the next iteration of a loop.
return	Exits from a method and optionally returns a value.

Exception Handling Keywords

Used for handling and managing runtime errors in programs.

Keyword	Usage
try	Defines a block of code to test for exceptions.
catch	Defines a block to handle exceptions thrown by `try`.
finally	Defines a block that always executes after `try` and `catch`.
throw	Used to manually throw an exception.
throws	Declares the exceptions a method can throw.
assert	Tests assumptions during program execution for debugging.

Object-Oriented Keywords

Used to define classes, interfaces, and objects, as well as inheritance and encapsulation properties.

Keyword	Usage
class	Declares a class.
interface	Declares an interface.
extends	Indicates inheritance from a superclass.
implements	Indicates that a class implements an interface.
new	Creates new objects.
this	Refers to the current object.
super	Refers to the superclass of the current object.
abstract	Declares a class or method that must be implemented in a subclass.
final	Prevents inheritance, overriding, or modification.
static	Declares class-level variables or methods.
sealed	Restricts which classes can extend a given class.
permits	Specifies the subclasses allowed to extend a sealed class.
enum	Declares a fixed set of constants.
record	Declares an immutable data class (Java 16+).
instanceof	Checks whether an object is of a specific type.

Access Control Keywords

Define the visibility or accessibility of classes, methods, and variables.

Keyword	Usage
public	Accessible from anywhere in the program.
protected	Accessible within the same package or by subclasses.
private	Accessible only within the same class.

Package and Import Keywords

Used to organize classes and access external code.

Keyword	Usage
package	Defines a namespace for classes.
import	Allows access to classes from other packages.

Multithreading and Synchronization Keywords

Used to handle concurrent execution of code and ensure thread safety.

Keyword	Usage
synchronized	Defines critical sections that only one thread can access at a time.
volatile	Indicates that a variable may change asynchronously.

Memory Management and Object Serialization Keywords

Handle object persistence, garbage collection, and native method calls.

Keyword	Usage
transient	Excludes a variable from serialization.
native	Specifies that a method is implemented in native (non-Java) code.

Modifier and Utility Keywords

Define additional behaviors and precision control.

Keyword	Usage
strictfp	Ensures consistent floating-point calculations across platforms.

Reserved (Unused) Keywords

These keywords are reserved but not currently used by Java.

Keyword	Usage
const	Reserved for future use; not currently implemented.
goto	Reserved for future use; not currently implemented.

Special Literals

Special literals represent predefined constant values in Java and cannot be used as identifiers.

Keyword	Usage
true	Represents the boolean value true.
false	Represents the boolean value false.
null	Represents the absence of any reference value.

Keywords vs Identifiers in Java

Feature	Keywords	Identifiers
Definition	Reserved words with predefined meanings in Java	User-defined names used for variables, methods, classes, etc.
Purpose	Define the syntax and structure of Java programs	Identify program elements
Can be Modified	No	Yes
Usage as Variable Name	Not allowed	Allowed
Predefined by Java	Yes	No
Examples	int, class, if, return	studentName, calculateSum, Employee
Case Sensitive	Yes	Yes
Compiler Meaning	Fixed meaning	Meaning defined by programmer

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