Instance Variable in Java Programming

Java Programming Language / Variables in java

5012

Program:

 class InstanceVariable {
int data=50;//instance variable

public static void main(String []args) {
      /* In this example if you want to access instanec variable'data' then you 
      have to create an instane of InstancVariable class like this*/
      InstanceVariable iv = new InstanceVariable();
      /* here iv is the name of the object or instance of the
	   InstanceVariable class */
      System.out.println(iv.data);
      /* to access the instance variable 'data' you have to write iv.data

   }
}

Output:

50
Press any key to continue . . .

Explanation:

Rules for Instance variable in Java

  • Instance variables can use any of the four access levels
  • They can be marked final
  • They can be marked transient
  • They cannot be marked abstract
  • They cannot be marked synchronized
  • They cannot be marked strictfp
  • They cannot be marked native
  • They cannot be marked static

Cheatsheet

  • Public, Private, Protected all 3 access modifiers can be applied to Instance Variable(Default also).
  • Instance variable will get default value means instance variable can be used without initializing it. Same is not true for Local Variable.
  • Instance Variable can be marked final.
  • Instance Variable can be marked transient.
  • Instance Variable cannot be abstract.
  • Instance Variable can not have synchronized modifier.
  • Instance Variable can not have strictfp modifier.
  • Instance Variable can not have the native modifier.
  • Instance Variable can not have Static modifier as it will become Class level variable.
INSTANCE VARIABLE TYPE DEFAULT VALUE
boolean false
byte (byte)0
short (short) 0
int 0
long 0L
char u0000
float 0.0f
double 0.0d
Object null

This Particular section is dedicated to Programs only. If you want learn more about Java Programming Language. Then you can visit below links to get more depth on this subject.