final keyword
class
On a class it means you forbid to have a child class extending yours.
public final class finalClass
Attribute/Field
final MyObject value = new MyObject() means you won't be able to modify the instance of the object.
value = xxxx won't be allowed, but you still can modify the object itself value.field = "xxx";
Method
When you use final on a method, that means you'll forbid child classes that extends your class to override this method.
public final void finalMethod()
It can also be used on arguments, that means you don't allow other to modify the instance of the object you give.
public void myMethod(final MyObject myObject)
The end user won't be able to do myObject = ...
Finally block
finally block has nothing to do with final, it's used when catching Exception to ensure a part of code will be ran, wherever there is an exception or not.
try { ...}
catch {} // Optional
finally { // Code that will be ran, exception or not being thrown}
Finalize method
It's called on every object when it's destroyed (usually garbage collected).
Answer from Michael Laffargue on Stack Overflowfinal keyword
class
On a class it means you forbid to have a child class extending yours.
public final class finalClass
Attribute/Field
final MyObject value = new MyObject() means you won't be able to modify the instance of the object.
value = xxxx won't be allowed, but you still can modify the object itself value.field = "xxx";
Method
When you use final on a method, that means you'll forbid child classes that extends your class to override this method.
public final void finalMethod()
It can also be used on arguments, that means you don't allow other to modify the instance of the object you give.
public void myMethod(final MyObject myObject)
The end user won't be able to do myObject = ...
Finally block
finally block has nothing to do with final, it's used when catching Exception to ensure a part of code will be ran, wherever there is an exception or not.
try { ...}
catch {} // Optional
finally { // Code that will be ran, exception or not being thrown}
Finalize method
It's called on every object when it's destroyed (usually garbage collected).
Final:- It is used in the following cases:
- If the final keyword is attached to a variable then the variable becomes constant i.e. its value cannot be changed in the program.
- If a method is marked as final then the method cannot be overridden by any other method.
- If a class is marked as final then this class cannot be inherited by any other class.
- If a parameter is marked with final it becomes a read only parameter.
Finally:-
If an exception is thrown in try block then the control directly passes to the catch block without executing the lines of code written in the remainder section of the try block. In case of an exception we may need to clean up some objects that we created. If we do the clean-up in try block, they may not be executed in case of an exception. Thus finally block is used which contains the code for clean-up and is always executed after the try ...catch block.
Finalize:-
It is a method present in a class which is called before any of its object is reclaimed by the garbage collector. finalize() method is used for performing code clean-up before the object is reclaimed by the garbage collector.