



List of all Java Keywords


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 a variable names or objects. Doing this will result into a compile time error.
Java also contains a list of reserved words or keywords. These are:

 abstract     -Specifies that a class or method will be implemented later, in a subclass

 assert         -Assert describes a predicate (a true–false statement) placed in a Java program to indicate that the developer thinks that the predicate is always true at that place. If an assertion evaluates to false at run-time, an assertion failure results, which typically causes execution to abort.

 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 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           -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 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      -Indicates that a variable may change asynchronously

 while         -Starts a while loop


** The keywords const and goto are reserved, even they are not currently in use.

 const          -Reserved for future use

 goto           – Reserved for future use


 ** true, false and null look like keywords, but in actual they are literals. However they still can’t be used as identifiers in a program.





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