Reserved words in java

Introduction

In Java, some words are already reserved to perform specific tasks.
These words have special meaning in the Java language and cannot be used as identifiers such as variable names, method names, or class names.

Such predefined words are called reserved words in Java.

What Are Reserved Words in Java?

Reserved words are predefined keywords that are used by the Java compiler to understand the structure and logic of a program.

👉 If we try to use any reserved word as an identifier, the compiler will generate a compile-time error.

Categories of Reserved Words in Java

Java reserved words are grouped based on their purpose.

Reserved Words for Data Types

These keywords are used to define primitive data types.

byte
short
int
long
float
double
char
boolean

Reserved Words for Flow Control

These keywords control the execution flow of a program.

if
else
switch
case
default
for
do
while
break
continue
return

Keywords Used as Modifiers

These keywords define access level and behavior of variables, methods, or classes.

public
private
protected
static
final
abstract
synchronized
native
strictfp (introduced in Java 1.2)
transient
volatile

Keywords for Exception Handling

These keywords help handle runtime errors.

try
catch
finally
throw
throws
assert (introduced in Java 1.4)

Class-Related Keywords

These keywords are used while working with classes and packages.

class
package
import
extends
implements
interface

Object-Related Keywords

These keywords are related to object creation and reference.

new
instanceof
super
this

Void Return Type Keyword

If a method does not return any value, it must use the void keyword in Java.

void

👉 In Java, using void is mandatory, unlike C++ where it can be optional.

Unused Keywords in Java

Some keywords are reserved but not used in Java.

goto
👉 Banned in Java because it creates complex and confusing code.
const
👉 Java uses final instead of const.

⚠️ Using these keywords in a program will cause a compile-time error.

Reserved Literals in Java

These are fixed values and not keywords.

true – value for boolean type
false – value for boolean type
null – default value for object references

Enum Keyword

The enum keyword was introduced in Java 1.5.
It is used to define a group of named constants.

Example

Important Notes

All Java reserved words are written in lowercase
Java is case-sensitive
String, Integer, and main are not keywords
finalize() is a method, not a keyword

Which of the following are valid Java keywords?

Word	Valid
public	✅
static	✅
void	✅
main	❌
String	❌
args	❌

Conclusion

Reserved words are the core building blocks of the Java language. They help the compiler understand how the program should behave. Since these words have predefined meanings, they cannot be used as identifiers. Learning reserved words is essential for writing error-free Java programs.

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Java Quiz : Reserved words in java

Quiz related to reserved word in java

1 / 7

What are reserved words in Java?

User-defined variable names

Predefined words with special meaning

Java class names

2 / 7

Which of the following cannot be used as an identifier in Java?

totalMarks

number1

_count

3 / 7

Which keyword is used to handle exceptions in Java?

try

catch

finally

All of the above

4 / 7

Which keyword is used to create an object in Java?

class

this

new

super

5 / 7

Which of the following is an unused keyword in Java?

goto

const

both a and b

continue

6 / 7

Which keyword was introduced in Java 1.5?

strictfp

assert

enum

volatile

7 / 7

Which of the following are valid Java keywords?

main

String

args

public

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