final

问题 This question already has answers here : Use of uninitialized final field - with/without 'this.' qualifier (4 answers) Closed 5 years ago . I wrote this piece of code and it seems compiler allows accessing uninitialized blank final field when accessed using 'this' keyword: public class TestClass { public final int value1; public int value2; TestClass(int value) { value2 = 2 + this.value1; // access final field using 'this' before initialization gives no compiler error //value2 = 2 + value1; /

问题 I am reviewing the Sun Certification study guide and there is a passage which describes the final modifier. It says "If programmers were free to extend the String class civilisation as we know it could collapse" What does he mean ? If it were possible to extend String Class ... would I just not have a class called MyString which inherits all of the Strings properties. How would it be possible to change the actual String class in any way by only extending it ? Thank you very much for your

问题 I wonder how variables marked as final are interpreted by Groovy (in 1.8.0, 1.8.1). I know that it makes sense in Java and it is possible to improve the performance and -- of course -- help to avoid stupid mistakes. I would like to learn if final may help the java compiler to optimize a program written in Groovy. I wonder if Groovy transformers preserve the final markings for variables. 回答1: As Justin has said, if the optimisations that the compiler performs for final variables are important

问题 Which one of these ways of publishing global constants is better? THANKS!!! Method 1: final class with public static final fields public final class CNST{ private CNST(){} public static final String C1; public static final String C2; static{ C1="STRING1"; C2="STRING2"; } } //so I could call C1, C2 like: //...some code... //System.out.println(CNST.C1); //System.out.println(CNST.C2); Method 2: singleton with enum public enum CNST{ INST; public final String C1; public final String C2; CNST{ C1=

问题 When I try to put final in method parameter eclipse doesn't help. Any idea how to get this to work? 回答1: I don't think this is possible. The closest thing to this is to set a "save action" which will automatically add final modifiers to method parameters when you save the file. Preferences > Java > Editor > Save Actions 回答2: This probably will be as close as you can get to it. It would be a lot of work to do this for every keyword, but since there is only so many of them it's possible. You

问题 I have a problem with Fortran destructors/final routines. Having the code below: module my_type_module implicit none type my_type contains final :: destructor end type my_type interface my_type ! Constructor declaration module procedure my_type_constructor end interface my_type contains function my_type_constructor() type(my_type) :: my_type_constructor print *, 'In constructor address is: ', & loc(my_type_constructor) end function my_type_constructor subroutine destructor(this) type(my_type)

问题 I have read that making something final and then using it in a loop will bring better performance, but is it good for everything? I have lots of places where there isnt a loop but I add final to the local variables. Does it make it slower or is it still good? Also there are some places where I have a global variable final (e.g. android paint), does it mean I don't have to make it a local final when using it in loops? 回答1: The first thing you should consider is; What is the simplest and

问题 I'm still pretty new to Scala, but I know you can define class variables that are initialized in the constructor like class AClass(aVal: String) which would be like doing the following in java class AClass { private String aVal; public AClass(String aVal) { this.aVal = aVal; } } In Java, I would declare aVal as final. Is there a way to make the aVal variable final in the Scala syntax? EDIT: Here is what I am seeing when I compile the following Scala class: class AClass(aVal: String) { def

问题 Why can't a java nested Interface be non-static ? And why can't an inner class contain static non final members ? I came across the questions while going through Gosling and haven't been able to figure out the answer yet. 回答1: If an nested class is non-static (i.e. an inner class), this means that each instance of it is bound to an instance of the outer class. As an interface has no instances of its own, it seems to not be useful for the implementing classes to be bound to an outer object, so

问题 This question already has answers here : Java — private constructor vs final and more (3 answers) Closed 4 years ago . As per my understanding Final class A final class is simply a class that can't be extended. A class with single no argument private constructor A class with private constructors cannot be instantiated except form inside that same class. This make it useless to extend it from another class. But it does not mean it cannot be sub classed at all, among inner classes we can extend