03.01. 50 Keywords of Java

50 Keywords of Java


Keywords are reserved words in Java that have specific meanings and cannot be used for any other purpose, such as variable names or method names. Java has a total of 50 keywords, which are used to define the syntax and structure of Java programming language.

Here’s a list of Java keywords:

  • abstract: used to declare a class or method as abstract. An abstract class is a class that cannot be instantiated, and an abstract method is a method without a body that must be implemented in a subclass.
  • assert: used to perform assertion testing in Java. An assertion is a statement that should always be true, and if it is false, then an AssertionError is thrown.
  • boolean: used to declare a boolean variable, which can only have two values: true or false.
  • break: used to break out of a loop or switch statement.
  • byte: used to declare a byte variable, which is a data type that can store values from -128 to 127.
  • case: used in a switch statement to define a case label.
  • catch: used to catch and handle exceptions in Java.
  • char: used to declare a char variable, which is a data type that can store a single character.
  • class: used to declare a class in Java.
  • const: a keyword that was reserved but never implemented in Java.
  • continue: used to skip the current iteration of a loop and continue to the next iteration.
  • default: used in a switch statement to define a default case.
  • do: used to start a do-while loop.
  • double: used to declare a double variable, which is a data type that can store decimal values.
  • else: used in an if statement to define an alternative block of code to execute if the condition is false.
  • enum: used to declare an enumeration, which is a type that consists of a set of named constants.
  • extends: used to extend a class in Java.
  • final: used to declare a variable or method as final, which means that its value or implementation cannot be changed.
  • finally: used in a try-catch block to define a block of code that will always be executed, regardless of whether an exception is thrown or not.
  • float: used to declare a float variable, which is a data type that can store decimal values with less precision than double.
  • for: used to start a for loop.
  • goto: a keyword that was reserved but never implemented in Java.
  • if: used to define a conditional statement in Java.
  • implements: used to implement an interface in Java.
  • import: used to import a package or class into a Java program.
  • instanceof: used to check if an object is an instance of a particular class or interface.
  • int: used to declare an int variable, which is a data type that can store whole numbers.
  • interface: used to declare an interface in Java.
  • long: used to declare a long variable, which is a data type that can store larger whole numbers than int.
  • native: used to declare a method as native, which means that its implementation is provided by the underlying platform, rather than in Java code.
  • new: used to create a new object in Java.
  • package: used to define a package in Java.
  • private: used to declare a variable or method as private, which means that it can only be accessed within the same class.
  • protected: used to declare a variable or method as protected, which means that it can be accessed within the same class or any subclass.
  • public: used to declare a variable or method as public, which means that it can be accessed from anywhere in the Java program.
  • return: used to return a value from a method or exit a method without returning a value.
  • short: used to declare a short variable, which is a data type that can store smaller whole numbers than int.
  • static: used to declare a variable or method as static, which means that it belongs to the class rather than to individual objects of the class.
  • strictfp: used to enforce strict floating-point precision in Java.
  • super: used to call a method or constructor in the superclass.
  • switch: used to start a switch statement in Java.
  • synchronized: used to ensure that only one thread can access a block of code or object at a time in Java.
  • this: used to refer to the current object in Java.
  • throw: used to throw an exception in Java.
  • throws: used to declare that a method may throw an exception in Java.
  • transient: used to declare a variable as transient, which means that it will not be serialized when the object is written to a file or transmitted over a network.
  • try: used to start a try-catch block in Java.
  • void: used to declare a method that does not return a value.
  • volatile: used to declare a variable as volatile, which means that it is subject to optimization by the Java Virtual Machine.

Rules to follow for keywords:

  • Keywords cannot be used as an identifier for class, subclass, variables, and methods.
  • Keywords are case-sensitive.

Here is a list of keywords in the Java programming language:

abstract assert boolean break byte
case catch char class const*
continue default do double else
enum extends final finally float
for goto* 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

Some significant points about Java keywords:

  • const and goto are reserved words but not used.
  • True, false, and null are literals, not keywords.
  • All keywords are in lower-case.

Source: https://docs.oracle.com/javase/tutorial/java/nutsandbolts/keywords.html

Contributed by: Salim Sheikh

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jrbr
jrbr
3 years ago

C++ has 95 keywords 😛

C has 32

Smaltak has 6

I think 30 keywords is excessive but its still better than 50 or more.

Emad Ali Alsaba
Emad Ali Alsaba
2 years ago

thread and runnable ()-> not within!!