Island problem in Java

After an object has been used, it is deallocated from the memory using the Garbage Collector class. The objects are destroyed based on the fact that no reference to that object is present. The Garbage Collector class calls the 'finalize' function on the object that needs to be destroyed.

What is island of isolation?

When two objects 'a', and ' b' reference each other, and they are not referenced by any other object, it is known as island of isolation.

It is a group of objects which reference each other but they are not referenced but other objects of other applications at all.

Note − A single unreferenced object is also an island of isolation.

Let us see an example −

Example

Live Demo

public class Demo{
   Demo i;
   public static void main(String[] args){
      Demo my_ob_1 = new Demo();
      System.out.println("Demo object one has been created");
      Demo my_ob_2 = new Demo();
      System.out.println("Demo object two has been created");
      my_ob_1.i = my_ob_2;
      my_ob_2.i = my_ob_1;
      my_ob_1 = null;
      my_ob_2 = null;
      System.gc();
   }
   @Override
   protected void finalize() throws Throwable{
      System.out.println("The finalize method has been called on the object");
   }
}

Output

Demo object one has been created
Demo object two has been created
The finalize method has been called on the object
The finalize method has been called on the object

A class named Demo contains the main function. Here, a variable of type Demo class is created. An instance of the Demo class is created and the second object is assigned to the Demo object of the first object. The same goes for the second object. Now, both objects are assigned null and 'System.gc' function is called. Now, the 'finalize' function is overridden.

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