•  Any variable declare along with final modifier then those variables treated as final variables
  • if we declare final variables along with static will became constants.
  • public final String name = "foo"; //never change this value
  • If you declare method as final that method also known as final methods.Final methods are not overridden.means we can't overridden that method in anyway.
  • public final void add(){
     public class A{
     void add(){
     //Can't override

  • If you declare class is final that class is also known as final classes.Final classes are not extended.means we can't extens that calss in anyway.
  • public final class indhu{
     public class classNotAllowed extends indhu {...} //not allowed


  • Finally blocks are followed by try or catch.finally blocks are complasary executable blocks.But finally is useful for more than just exception handling.
  •  it allows the programmer to avoid having cleanup code accidentally bypassed by a return,
     continue, or break,Closing streams, network connection, database connection. Putting cleanup  code in a finally block is always a good practice even when no exceptions are anticipated
  •  where finally doesn't execute e.g. returning value from finally block, calling System.exit from try block etc
  • finally block always execute, except in case of JVM dies i.e. calling System.exit() .

    try {
      //do stuff
    } catch (SomeException se) {
      //handle se
    } finally {
      lock.unlock(); //always executed, even if Exception or Error or se
      //here close the database connection and any return statements like that we have to write


  • finalize() is a method which is present in Java.lang.Object class.
  •  Before an object is garbage collected, the garbage collector calls this finalize() of object.Any unreferenced before destroying if that object having any connections with database or anything..It will remove  the connections and it will call finalize() of object.It will destroy the object.
  • If you want to Explicitly call this garbage collector you can use System.gc() or Runtime.gc() objects are there from a long time the garbage collector will destroy that objects.
  • public void finalize() {
      //free resources (e.g. un allocate memory)

Instance Of Java

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