What is final, finally and finalize ?

Final

  • Final is used to apply limitations on class, method and variable. Final variable value couldn’t be changed final method couldn’t be overridden and final class can’t be inherited.
  • Final is a keyword.

Sample Code

  • Once initialized value of variable cannot be changed.
class A 
{ 
    public static void main(String[] args) 
    { 
        int a = 5; 
  
        // final variable 
        final int b = 6; 
  
         
        a++; 
  
        // modifying the final variable :  
        b++; 
    } 
}
  • If we declare any variable as final, we can’t change its contents since it is final, and if we change it then we have the Compile Time Error.

Finally

  • Finally is used to place significant code, whether exception is handled or not that time will be executed.
  • Finally is a block.

Sample Code

// A Java program to demonstrate finally. 
class Wikitechy
{ 
     
    static void A() 
    { 
        try 
        { 
            System.out.println("inside A"); 
            throw new RuntimeException("demo"); 
        } 
        finally
        { 
            System.out.println("A's finally"); 
        } 
    }  
    static void B() 
    { 
        try 
        { 
            System.out.println("inside B"); 
            return; 
        } 
        finally
        { 
            System.out.println("B's finally"); 
        } 
    } 
  
    public static void main(String args[]) 
    { 
        try 
        { 
            A(); 
        } 
        catch (Exception e) 
        { 
            System.out.println("Exception caught"); 
        } 
        B(); 
    } 
}

Output

inside A
A's finally
Exception caught
inside B
B's finally

Finalize

  • Finalize is using for the processing of clean up to be perform just before object is garbage collected.
  • Finalize is a method.
  • Once finalize method completes immediately Garbage Collector destroy that object.

Syntax

protected void finalize throws Throwable
{

}

Sample Code

class Wikitechy 
{ 
    public static void main(String[] args) 
    { 
        String s = new String("RR"); 
        s = null; 
  
        // Requesting JVM to call Garbage Collector method 
        System.gc(); 
        System.out.println("Main Completes"); 
    } 
  
    // Here overriding finalize method 
    public void finalize() 
    { 
        System.out.println("finalize method overriden"); 
    } 
}

Output

Main Completes

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