Keyword / Reserved words in Java Programming | this, final and super Keywords in Java

Keywords in Java

Keywords are predefined reserved words used in Java programming which have been described/told to the Java compiler already. We can't use a keyword as a variable name, class name or an identifier, as they are predefined in Java and using them will throw error.

For example:

int value1;

Here, "int" is a keyword. It indicates that the variable ‘value1’ is of integer type.

Below is the complete list of all keywords/reserved words in Java programming.

In java there are total 50 + 03 (literals) keywords/reserved words in Java.

Let us see in detail on some of the keywords/reserved words and their functions in Java.

• break: It is used inside a loop to bring the program control out of the loop or to terminate the loop immediately after some condition got true.
• continue: The ‘continue keyword’ in a loop ends the current iteration and forces the next iteration to take place bypassing any other statements inside.
• switch: We use ‘switch’ keyword to perform a block of statements/code that is when you have to execute/run a different task for each choice.
• int: Keyword/reserved word ‘int’ declares the data type integer. 
• char: This keyword/reserved word ‘char’ declares a character variable.
• if…else: In Java programming, the if and else are conditional statements used in decision making scenery.
• goto: we use "goto" keyword when we have to transfer the program control to a particular label.
• return: it is used to terminates the function and returns a value.
• void: ‘Void’ means null or no value
• this keyword: Java defines the this keyword. It is used inside any method to refer to the current object. That is, this is always a reference to the object on which the method was invoked/called. You can use this anywhere in  a reference to an object of the current class.
• final keyword: If we make any variable final then we are not allowed to change its value later.It will be a constant.If we try to change value, then compiler will give us error.
• super keyword: Super keyword/reserved word in Java is simply a reference variable. It refer to the immediate parent class object.

Identifiers in Java

Names given to constants, functions, variables and user-define data are known as Identifiers. It is assigned by the user.

There are a set of rules to frame/make an Identifier.

• An identifier must be of alphanumeric values only i.e letters and digits. (A-Z, a-z, 0-9)
• Underscore ( _ ) can be used in an identifier.
• Identifier names must be unique in the program.
• Keywords/Reserved words cannot be an Identifier.
• No special character is allowed in identifier.
• The first character of an identifier must be an alphabet or underscore only.
• Identifiers are case-sensitive.
• No white spaces are allowed in a identifier name.