Java Final, Finally, Finalize

Final is a Keyword, final can be used in three different ways:

1. final variable
2. final method
3. final class

1. final variable 基本上就是 constant，一旦被赋值，就不能被变更；如果在class里declare a final variable, 那么在此class生成出的object就必须对这个 final variable赋值。
2. final method 是method can't be over overridden.
3. final class is a class can't be inherited.

Finally is used in try/catch block, it is guaranteed to be executed no matter exception is thrown or not.

Circumstances that finally block are NOT executed:

1. System.exit() is called in try block
2. Another thread interrupts current one
3. JVM crashes first

Fianllize is a method. finalize() is called by Garbage collection thread just before collecting eligible objects.