In Java, what purpose do the keywords final
, finally
and finalize
fulfil?
相关问题
- Delete Messages from a Topic in Apache Kafka
- Jackson Deserialization not calling deserialize on
- How to maintain order of key-value in DataFrame sa
- StackExchange API - Deserialize Date in JSON Respo
- Difference between Types.INTEGER and Types.NULL in
final
final
can be used to mark a variable "unchangeable"final
can also make a method not "overrideable"final
can also make a class not "inheritable". i.e. the class can not be subclassed.finally
finally
is used in a try/catch statement to execute code "always"Java 7 has a new try with resources statement that you can use to automatically close resources that explicitly or implicitly implement java.io.Closeable or java.lang.AutoCloseable
finalize
finalize
is called when an object is garbage collected. You rarely need to override it. An example:http://allu.wordpress.com/2006/11/08/difference-between-final-finally-and-finalize/
Did you try searching on google, and need clarification for an explanation?
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.
1. Final • Final is used to apply restrictions on class, method and variable. • Final class can't be inherited, final method can't be overridden and final variable value can't be changed. • Final variables are initialized at the time of creation except in case of blank final variable which is initialized in Constructor. • Final is a keyword.
2. Finally • Finally is used for exception handling along with try and catch. • It will be executed whether exception is handled or not. • This block is used to close the resources like database connection, I/O resources. • Finally is a block.
3. Finalize • Finalize is called by Garbage collection thread just before collecting eligible objects to perform clean up processing. • This is the last chance for object to perform any clean-up but since it’s not guaranteed that whether finalize () will be called, its bad practice to keep resource till finalize call. • Finalize is a method.
The final keyword is used to declare constants.
The finally keyword is used in a try catch statement to specify a block of code to execute regardless of thrown exceptions.
And finally (haha), finalize im not entirely sure is a keyword, but there is a finalize() function in the Object class.