Java Keywords Dictionary

What is Keyword?

  • Keywords are the reserved words used in programming.
  • They have special meanings to the compiler.
  • They cannot be used as indetifier in the program.
  • Example - class,int,public,goto,return etc are the keywords.

Keywords list

abstract assert boolean break byte
case catch char class continue
default do double else enum
extends final finally float for
if implements import instanceof int
interface long native new package
private protected public return short
static strictfp super switch synchronized
this throw throws transient try
void volatile while

Reserved for Literals

true null false

Unused keywords

const goto

Keywords Dictionary

abstract

The keyword abstract is used for making methods and classes abstract. Abstracts are used to implement an abstraction in Java.
assert

assert keyword is used in the assertion statements.Assertion statements provide the best way to detect and correct the programming errors. Assertion statements take one boolean expression as input and assumes that this will be always true.
boolean

Boolean defines only two values True and False. They are mostly used in the decision making statement.
break

The Break statement is used to exit from the loop for a particular condition. It is used in the switch case and looping.
byte

Byte keyword is used to declare a variable of 1 byte of size.
case

Case keyword is used inside the switch statement.Compiler jumps into a particular case statement after evaluating a test expression.
catch

Catch keyword is used in the try catch statement in exeception handling.
char

Char keyword is used to declare a character type variable. It holds only single character.
class

Class keyword is used to declare a class in java. class is user defined data type.
continue

Continue keyword is used to skip current iteration of loop and execute the next statement inside the loop.
default

Default keyword is used inside the switch case statement.If any case statement is not matched the default statement is executed.
do

Do keyword is used in the looping like do-while loop.
double

Double keyword is used to declare a variable of 8 byte. it holds floating values.
else

Else keyword is used to with if statement. when if condition becomes false then else block is executed.
enum

Enum keyword is used to declare an enumerated type.
extends

Extends keyword is used to to access properties of parent class and interface.
final

final keyword is used to declare unmodifidable class, constant variables and preveting overriding.
finally

finally keyword is used with try-catch statement in exeception handling. Finally block is always executed after try-catch statement.
float

float keyword is used to declare a variable of 4 byte size. It stores floating point numbers.
for

for keyword is used to create a for loop. It contains 3 statement - initialization,condition,increment/decrement.
if

if keyword is used to create if statement in decision making.
implements

implements keyword is used write implementation of interface. It is also used to achive multiple inheritance.
import

import keyword is used to use packages.
instanceof

iThe instanceof operator evaluates to true if and only if the runtime type of the object is assignment compatible with the class or interface.
int

Int keyword is used to declare a variable of 4 byte size. It holds only integer values.
interface

Interface contains only abstract methods and final fields.
long

Long keyword is used to declare a variable of 8 byte size.
native

Native is used in method declarations to specify that the method is not implemented in the same Java source file, but rather in another language
new

The new keyword is used to create an instance of a class or array object.
package

Java package is a group of similar classes and interfaces. Packages are declared with the package keyword.
private

The private keyword is used in the declaration of a method, field, or inner class; private members can only be accessed by other members of their own class.
protected

The protected keyword is used in the declaration of a method, field, or inner class,protected members can only be accessed by members of their own class, that class's subclasses or classes from the same package.
public

The public keyword is used in the declaration of a class, method, or field; public classes, methods, and fields can be accessed by the members of any class.
return

Used to finish the execution of a method. It can be followed by a value required by the method definition that is returned to the caller.
short

The short keyword is used to declare a field that can hold a 2 byte signed two's complement integer.
static

Static keyword is used to make static members. The static members are associated with class itself rather than individual objects. They are also referred as class variables and class methods.
strictfp

A Java keyword used to restrict the precision and rounding of floating point calculations to ensure portability.
super

The super keyword is used to invoke the super class constructor from subclass constructor function. In Java Subclass can access all the members of superclass (base class) except private data members. When the superclass is created which wants to keep it's private data members itself only. In such type of problem Subclass cannot access these members directly.
switch

Switch case is similar to the if else statement, But the reason for switch case use is that switch knows which case need to be executed.
synchronized

Used in the declaration of a method or code block to acquire the mutex lock for an object while the current thread executes the code.
this

This keyword is used to refer current object of a class.The members of the current object like instance method or field can be referred by using this pointer.
throw

Throw keyword is used for manually (explicitly) throwing an exception.
throws

Throws keyword allows us to execute multiple exceptions from a method.
transient

Declares that an instance field is not part of the default serialized form of an object. When an object is serialized, only the values of its non-transient instance fields are included in the default serial representation.
try

All program statements which are going to generate an exception are written inside the try block.
void

The void keyword is used to declare that a method does not return any value.
volatile

Used in field declarations to specify that the variable is modified asynchronously by concurrently running threads. Methods, classes and interfaces thus cannot be declared volatile, nor can local variables or parameters.
while

The while keyword is used to create a while loop, which tests a boolean expression and executes the block of statements associated with the loop if the expression evaluates to true; this continues until the expression evaluates to false.
true

True keyword is similar to the 1. It is used to denote a particular condition is true.
null

Null is a reference of iteral value. It indicated empty.
false

False keyword is similar to the 0. It is used to denote a particular condition is false.
const

For defining any constants the const keyword is used.
goto

The goto is not used and has no function.