Instance Variables in Java

Instance Variables in Java

Instance variables should declare with in the class but outside of any method or block or constructor.instance variables can accessible inside class all methods , blocks & constructors.
  • Objects store their individual states(values) in Instance Variables.
  • Instance variable values are unique to each Object.
  • Instance variables are stored in Heap Memory.
  • Instance variables can be accessed by using Object reference.
  • Instance Variables will  get default values.
Example for instance variables with default values
File:Instance_Variable_Demo.java
package com.practice;

public class Instance_Variable_Demo {
int id;// instance variable declaration
String name;// instance variable declaration
boolean b;// local variable declaration

public static void main(String[] args) {
Instance_Variable_Demo instance_Variable_Demo = new Instance_Variable_Demo();
System.out.println(instance_Variable_Demo.id);
System.out.println(instance_Variable_Demo.name);
System.out.println(instance_Variable_Demo.b);

}

}
output
0
null
false
Example for instance variables with initialized values
package com.practice;

public class Instance_Variable_Demo {
int id = 100;// instance variable declaration
String name = "java2study";// instance variable declaration
boolean b = true;// local variable declaration

public void show_Instance_variables() {
System.out.println(id);
System.out.println(name);
System.out.println(b);

}

public static void main(String[] args) {
Instance_Variable_Demo instance_Variable_Demo = new Instance_Variable_Demo();

instance_Variable_Demo.show_Instance_variables();
}

}
output
100
java2study
true
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