Difference between final, finally and finalize

by Online Tutorials Library July 22, 2022

Difference between final, finally and finalize

The final, finally, and finalize are keywords in Java that are used in exception handling. Each of these keywords has a different functionality. The basic difference between final, finally and finalize is that the final is an access modifier, finally is the block in Exception Handling and finalize is the method of object class.

Along with this, there are many differences between final, finally and finalize. A list of differences between final, finally and finalize are given below:

Sr. no.	Key	final	finally	finalize
1.	Definition	final is the keyword and access modifier which is used to apply restrictions on a class, method or variable.	finally is the block in Java Exception Handling to execute the important code whether the exception occurs or not.	finalize is the method in Java which is used to perform clean up processing just before object is garbage collected.
2.	Applicable to	Final keyword is used with the classes, methods and variables.	Finally block is always related to the try and catch block in exception handling.	finalize() method is used with the objects.
3.	Functionality	(1) Once declared, final variable becomes constant and cannot be modified. (2) final method cannot be overridden by sub class. (3) final class cannot be inherited.	(1) finally block runs the important code even if exception occurs or not. (2) finally block cleans up all the resources used in try block	finalize method performs the cleaning activities with respect to the object before its destruction.
4.	Execution	Final method is executed only when we call it.	Finally block is executed as soon as the try-catch block is executed. It’s execution is not dependant on the exception.	finalize method is executed just before the object is destroyed.

Java final Example

Let’s consider the following example where we declare final variable age. Once declared it cannot be modified.

FinalExampleTest.java

  public class FinalExampleTest {  //declaring final variable  final int age = 18;  void display() {    // reassigning value to age variable   // gives compile time error  age = 55;  }    public static void main(String[] args) {    FinalExampleTest obj = new FinalExampleTest();  // gives compile time error  obj.display();  }  }  

Output:

In the above example, we have declared a variable final. Similarly, we can declare the methods and classes final using the final keyword.

Java finally Example

Let’s see the below example where the Java code throws an exception and the catch block handles that exception. Later the finally block is executed after the try-catch block. Further, the rest of the code is also executed normally.

FinallyExample.java

  public class FinallyExample {      public static void main(String args[]){     try {      System.out.println(“Inside try block”);    // below code throws divide by zero exception     int data=25/0;       System.out.println(data);      }     // handles the Arithmetic Exception / Divide by zero exception    catch (ArithmeticException e){    System.out.println(“Exception handled”);    System.out.println(e);    }     // executes regardless of exception occurred or not     finally {    System.out.println(“finally block is always executed”);    }      System.out.println(“rest of the code…”);      }    }    

Output:

Java finalize Example

FinalizeExample.java

  public class FinalizeExample {         public static void main(String[] args)         {             FinalizeExample obj = new FinalizeExample();                // printing the hashcode           System.out.println(“Hashcode is: ” + obj.hashCode());                   obj = null;            // calling the garbage collector using gc()           System.gc();             System.out.println(“End of the garbage collection”);         }        // defining the finalize method       protected void finalize()         {             System.out.println(“Called the finalize() method”);         }     }    

Output:

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