Scope and Lifetime of variables in java.

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Scope and Lifetime of variables in java.


Scope of a variable :it refers to in which areas or sections of a program can the variable be accessed .

Or

Scope of a variable it refers region/location/range in the program where the variable is visible/accessible.


Lifetime of a variable: it refers to how long the variable stays alive in memory.
The lifetime of a variable is the time period in which the variable has valid memory.

Or

Lifetime of a variable : it refers to time duration between variable creation and destroy in memory.


There are three types of variables in java:


1) instance variables :


 scope of an instance variable is throughout the class except in static methods. 


Lifetime of an instance variable is until the object stays in memory.


2) class variables :


scope of a class variable is throughout the class.


 lifetime of a class variable is until the end of the program or as long as the class is loaded in memory.


3) local variables:


Scope of a local variable iis within the block in which it is declared.  


lifetime of a local variable is until the control leaves the block in which it is declared.


Shortcut summary for all variables:



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