Variables/Identifier in Java
Identifiers are used in java program for Identification purpose.
Whatever the name we are using in java program is called as Identifier It can class Name , Method Name, Variable Name.
Question = Why we use Identifiers?
Answer = TO Identification purpose.
1 – The valid characters in java Identifiers are :
a – z, A – Z, 0 – 9, underscore (_), dollar symbol ($).
2 – Identifiers should not start from Digit :
3 – No length Restriction but choose short name as Identifiers.
4 – Java Identifiers are case sensitive.
5 – we can’t use keywords/reserved word as Identifiers.
int if=10; [invalid]
int double=10; [valid]
class class=10; [invalid]
6 – All predefine classes and Identifiers are allowed to use as Identifiers.
int Runnable=30; //valid Runnable is predefined interface.
Note :- from java 9 version on word ,_(underscore) is keyword then we can not use as Identifier.
Ex – int_=10; (java 8)is valid.
int_=10; (java 8)is invalid.
We can’t say keywords as identifiers.
Question = Which of following valid identifiers in java 11?
Answer = int _a=15; [valid]
Int __d=30; [valid]
int _=35; [invalid]
How many identifiers are present in this program ——
Total five identifiers in this program (Test, main, string, ar, x)
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