What is the difference between final, finally, and finalize in Java?

Final When applied to a variable (primitive): The value of the variable cannot change. When applied to a variable (reference): The reference variable cannot point to any other object on the heap. When applied to a method: The method cannot be overridden. When applied to a class: The class cannot be subclassed. Finally There is an optional finally block after the try block or after the catch block. Statements in the finally block will always be executed (except if JVM exits from the try block). The finally block is used to write the clean up code. Finalize This is the method that the JVM runs before running the garbage collector.

final - final keyword can be used with a class, variable or a method. A variable declared as final acts as constant, which means one a variable is declared and assigned , the value cannot be changed. An object can also be final, which means that the once the object is created it cannot be assigned a different object, although the properties or fields of the object can be changed. A final class is immutable, which means that no other class can extend from it. E.g String, Integer. A final method in a class cannot be overridden in the child class. finally - finally keyword is used with try-catch block for handling exception. The finally block is optional in try-catch block. The finally code block is always executed after try or catch block is completed. The general use case for finally block is to close the resources or clean up objects used in try block. For e.g. Closing a FileStream, I/O stream objects, Database connections, HTTP connections are generally closed in a finally block.finalize() - This is the method of Object class. It is invoked before an object is discarded by the garbage collector, allowing it to clean up its state. Should not be used to release non-memory resources like file handles, sockets, database connections etc because Java has only a finite number of these resources and you do not know when the garbage collection is going to kick in to release these non-memory resources through the finalize() method.Source taken from http://java-questions.com/difference-between-final-finally-and-finalize.html

FinalFinal offers restrictions on classes,methods and variables.One they are final,they cannot be changed(immutable).public class Test { private static final String PREFIX = "test." ;  private final MyClass obj = new Myclass(); publc Test() {    obj = new MyClass() ;// throws error    obj is final so we cant instantiate it again}}public class Test {  private static final String PREFIX = "test."   private final MyClass obj;  publc Test() {    obj = new MyClass() ;// this works  because obj is instantiated in constructor }}FinallyFinally is a block used with try ,catch http://block.It will always get executed after try or catch block.try {    //code...} catch (Exception e) {    //code...} finally {    System.out.println("This line is always printed");}Putting cleanup code in a finally block is always a good practice, even when no exceptions are anticipated.When closing a file or otherwise , place the code in a finally block.Finalisewhen the memory is overloaded with  objects the system.gc(; will call finalize methodWhen the memory is getting overloaded then the finalize method will be called.public class TestGarbageCollection {    public static void main(String[] args) {        while (true) {            TestClass s = new TestClass();            s.display();            System.gc();        }    }}

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final: final is a keyword. The variable decleared as final should be initialized only once and cannot be changed. Java classes declared as final cannot be extended. Methods declared as final cannot be overridden. finally: finally is a block. The finally block always executes when the try block exits. This ensures that the finally block is executed even if an unexpected exception occurs. 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. Putting cleanup code in a finally block is always a good practice, even when no exceptions are anticipated. finalize: finalize is a method. Before an object is garbage collected, the runtime system calls its finalize() method. You can write system resources release code in finalize() method before getting garbage collected.