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:

  1. abstract -Specifies that a class or method will be implemented later, in a subclass
  2. 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.
  3. boolean – A data type that can hold True and False values only
  4. break – A control statement for breaking out of loops
  5. byte – A data type that can hold 8-bit data values
  6. case – Used in switch statements to mark blocks of text
  7. catch – Catches exceptions generated by try statements
  8. char – A data type that can hold unsigned 16-bit Unicode characters
  9. class -Declares a new class
  10. continue -Sends control back outside a loop
  11. default -Specifies the default block of code in a switch statement
  12. do -Starts a do-while loop
  13. double – A data type that can hold 64-bit floating-point numbers
  14. else – Indicates alternative branches in an if statement
  15. enum – A Java keyword used to declare an enumerated type. Enumerations extend the base class.
  16. extends -Indicates that a class is derived from another class or interface
  17. final -Indicates that a variable holds a constant value or that a method will not be overridden
  18. finally -Indicates a block of code in a try-catch structure that will always be executed
  19. float -A data type that holds a 32-bit floating-point number
  20. for -Used to start a for loop
  21. if -Tests a true/false expression and branches accordingly
  22. implements -Specifies that a class implements an interface
  23. import -References other classes
  24. instanceof -Indicates whether an object is an instance of a specific class or implements an interface
  25. int – A data type that can hold a 32-bit signed integer
  26. interface – Declares an interface
  27. long – A data type that holds a 64-bit integer
  28. native -Specifies that a method is implemented with native (platform-specific) code
  29. new – Creates new objects
  30. null -Indicates that a reference does not refer to anything
  31. package – Declares a Java package
  32. private -An access specifier indicating that a method or variable may be accessed only in the class it’s declared in
  33. 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)
  34. 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)
  35. return -Sends control and possibly a return value back from a called method
  36. short – A data type that can hold a 16-bit integer
  37. static -Indicates that a variable or method is a class method (rather than being limited to one particular object)
  38. strictfp – A Java keyword used to restrict the precision and rounding of floating point calculations to ensure portability.
  39. super – Refers to a class’s base class (used in a method or class constructor)
  40. switch -A statement that executes code based on a test value
  41. synchronized -Specifies critical sections or methods in multithreaded code
  42. this -Refers to the current object in a method or constructor
  43. throw – Creates an exception
  44. throws -Indicates what exceptions may be thrown by a method
  45. transient -Specifies that a variable is not part of an object’s persistent state
  46. try -Starts a block of code that will be tested for exceptions
  47. void -Specifies that a method does not have a return value
  48. volatile -Indicates that a variable may change asynchronously
  49. 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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