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Java Keywords

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In Java, Keywords or Reserved words are the words in a language that are used for some internal process or represent some predefined actions. These words are therefore not allowed to use as variable names or objects. 

If we do we will get a compile-time error as shown below as follows:

Example of Java Keywords

Java




// Java Program to Illustrate What If We use the keywords as
// the variable name
 
// Driver Class
class HelloWorld {
    // Main Function
    public static void main(String[] args)
    {
        // Note "this" is a reserved
        // word in java
        String this = "Hello World!";
        System.out.println(this);
    }
}
// Code Contributed by @Shubham Jain


Output:

./HelloWorld.java:6: error: not a statement
String this = "Hello World!"; System.out.println(this);
^
./HelloWorld.java:6: error: ';' expected
String this = "Hello World!"; System.out.println(this);
^
2 errors

List of all Keywords in Java

Java contains a list of keywords or reserved words which are also highlighted with different colors be it an IDE or editor in order to segregate the differences between flexible words and reserved words. They are listed below in the table with the primary action associated with them.

Keyword Usage
abstract Specifies that a class or method will be implemented later, in a subclass 
assert Assert describes a predicate placed in a Java program to indicate that the developer thinks that the predicate is always true at that place.
boolean A data type that can hold True and False values only 
break A control statement for breaking out of loops.
byte A data type that can hold 8-bit data values 
case Used in switch statements to mark blocks of text
catch Catches exceptions generated by try statements
char A data type that can hold unsigned 16-bit Unicode characters
class Declares a new class
continue Sends control back outside a loop 
default Specifies the default block of code in a switch statement
do Starts a do-while loop
double A data type that can hold 64-bit floating-point numbers
else Indicates alternative branches in an if statement 
enum A Java keyword is used to declare an enumerated type. Enumerations extend the base class.
extends Indicates that a class is derived from another class or interface 
final Indicates that a variable holds a constant value or that a method will not be overridden
finally Indicates a block of code in a try-catch structure that will always be executed
float A data type that holds a 32-bit floating-point number 
for Used to start a for loop
if Tests a true/false expression and branches accordingly
implements Specifies that a class implements an interface 
import References other classes
instanceof Indicates whether an object is an instance of a specific class or implements an interface 
int A data type that can hold a 32-bit signed integer 
interface Declares an interface
long A data type that holds a 64-bit integer
native Specifies that a method is implemented with native (platform-specific) code 
new Creates new objects 
null This indicates that a reference does not refer to anything 
package Declares a Java package
private An access specifier indicating that a method or variable may be accessed only in the class it’s declared in
protected An access specifier indicating that a method or variable may only be accessed in the class it’s declared in (or a subclass of the class it’s declared in or other classes in the same package)
public An access specifier used for classes, interfaces, methods, and variables indicating that an item is accessible throughout the application (or where the class that defines it is accessible)
return Sends control and possibly a return value back from a called method 
short A data type that can hold a 16-bit integer 
static Indicates that a variable or method is a class method (rather than being limited to one particular object)
strictfp A Java keyword is used to restrict the precision and rounding of floating-point calculations to ensure portability.
super Refers to a class’s base class (used in a method or class constructor) 
switch A statement that executes code based on a test value 
synchronized Specifies critical sections or methods in multithreaded code
this Refers to the current object in a method or constructor 
throw Creates an exception 
throws Indicates what exceptions may be thrown by a method 
transient Specifies that a variable is not part of an object’s persistent state
try Starts a block of code that will be tested for exceptions 
void Specifies that a method does not have a return value
volatile This indicates that a variable may change asynchronously
while Starts a while loop

Important Points on Java Keywords

  • The keywords const and goto are reserved, even though they are not currently in use.
  • Currently, they are no longer supported in Java.
const Reserved for future use
goto Reserved for future use

FAQs on Java Keywords

1. What are the keywords of Java?

Keywords are the reserved words in Java having certain meanings. These words are not allowed to use as variable names or object names.

2. How many keywords are in Java?

There are 67 Keywords in Java.



Last Updated : 12 Jan, 2024
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