Static Instance Variable Difference Example
| Static Variable | Instance Variable |
| Static variable is one per class | Instance variable one per object |
| Every object of that class will share same static variable | Every object of that class will have its own copy of instance variable |
| Static variable is initialized when JVM loads the class | Instance variable initialize when object get created |
| Static method cannot access non static method or variable because it doesn’t have any state | Instance variable can access static variable or method (But because static is class level and it does not have state so access should be done through class) |
| Static variable can survive longer (Garbage collection) | Instance variable life is lesser in for garbage collection |
| Static is one per class so memory consumption is less | Instance variable is one per object so it’s takes for every object |
| Static variable only one memory location is allocated irrespective to no object created | Instance variable each object one memory location is allocated |
- Instance variable sample class:
package com.javahonk;
public class InstanceClassSample {
String name = "Java HOnk";
public void testName(){
//instanceClassSample and instanceClassSample2 will have it own copy of name
InstanceClassSample instanceClassSample = new InstanceClassSample();
InstanceClassSample instanceClassSample2 = new InstanceClassSample();
System.out.println(instanceClassSample.name);
System.out.println(instanceClassSample2.name);
}
}
- Static variable sample class:
package com.javahonk;
public class StaticSampleClass {
static String name = "Java HOnk";
public void testName(){
//instanceClassSample and instanceClassSample2 will have only one copy of name shared between them
StaticSampleClass instanceClassSample = new StaticSampleClass();
StaticSampleClass instanceClassSample2 = new StaticSampleClass();
}
}
Reference:
