Java Keywords

In Java, keywords are reserved words that have a special meaning in the Java language. These words cannot be used as variable names, class names, or method names because they are already defined by the Java compiler.

Java currently has 50+ reserved keywords. Each keyword plays an important role in defining classes, methods, variables, access control, loops, conditions, exception handling, and object-oriented programming concepts.

1. Access Modifiers

These keywords control the visibility (access level) of classes, variables, and methods.

public – Accessible from anywhere
private – Accessible only within the same class
protected – Accessible within the package and subclasses
default – Accessible within the same package (no keyword used)

public class Test {
private int age;
}

2. Class and Object Related Keywords

class – Defines a class
interface – Defines an interface
extends – Used for inheritance
implements – Used to implement an interface
new – Creates a new object
this – Refers to current object
super – Refers to parent class object

class Animal {}
class Dog extends Animal {}

Dog d = new Dog();

3. Data Type Keywords

These keywords define primitive data types in Java.

int
double
float
char
boolean
byte
short
long

int number = 10;
boolean status = true;

4. Control Flow Keywords

These keywords control the flow of execution in a program.

if
else
switch
case
default
for
while
do
break
continue
return

for(int i = 0; i < 5; i++){
System.out.println(i);
}

5. Exception Handling Keywords

try
catch
finally
throw
throws

try {
int result = 10 / 0;
} catch (ArithmeticException e) {
System.out.println("Error occurred");
}

6. Other Important Keywords

static – Belongs to class rather than object
final – Cannot be changed
abstract – Used for abstract classes and methods
synchronized – Used in multithreading
volatile – Used in multithreading
instanceof – Checks object type

final int MAX = 100;
if(obj instanceof String){
System.out.println("It is a String");
}

Why Java Keywords Are Important?

They form the foundation of Java syntax
Help define program structure
Essential for writing correct code
Important for exams and interviews
Used in almost every Java program

Helpful Tip: Try to memorize Java keywords with examples. Understanding their purpose is more important than just remembering the list.