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From .Net to Java

Which would be the best way to write the same code in Java?:
Array.Resize(ref DCamposGraficoOperaciones[index].DatosMeses, 12);
I have this code in C# and I have to put it on in Java. Thanks so much. I have a method called resizeDatosMeses in Java to resize the array but when I try to do it in this way:
DCamposGraficoOperaciones[index].getDatosMeses()=resizeDatosMeses(DCamposGraficoOperaciones[index].getDatosMeses(), 12)
I have a mistake which is: The left-hand side of an assignment must be a variable, please could you advice me?
Thanks so much

I suspect you want:
DCamposGraficoOperaciones[index].setDatosMeses(
resizeDatosMeses(DCamposGraficoOperaciones[index].getDatosMeses(), 12));
You can't assign to the result of a method call, which is what you were trying to do before.
I would strongly encourage you to break this line into two separate statements - and also start following Java naming conventions, which would prohibit DCamposGraficoOperaciones as a variable name.
Also, it's not clear why you're resizing an array to start with, but in both .NET and Java you may well be better off using a higher-level abstraction, e.g. List<T> in .NET or ArrayList<T> in Java.

In java you cant re-size arrays. You can use ArrayList and you can add any number of values to it.

Is there any good reason to write things "backwards", e.g.: if ("some_text" == var_name)?

I was doing a project in groups of 4 people, using C#.NET. While I naturally wrote down something like:
if (var_name == "some_text"), one of the group members strongly insisted to change that line into if ("some_text" == var_name) and claim "it's a better programming practice" that she learned from some sensor programmer. No one in our group, not even herself, understood what's the motivation behind this besides it feels more awkward. Is this a better practice or it's just another urban myth?

There's no good reason for this in C#.
In C you can inadvertently forget one of the = signs, and C allows this:
if (x = 5)
Which will compile and always return either true or false (true if the variable was set to any non-zero value, false if it was zero). This was a common source of errors, so writing if (5 == x) prevents this as the C compiler would complain if you ommitted one of the = signs.
C# however does NOT allow assignment to be treated as a boolean condition, and thus its impossible to make this mistake, so the suggestion is pointless. I'd recommend sticking to the more natural "if x equals 5" style.

Yes, I am not big fan of it.. But there is.. If you mistakenly would use operator assign (=) instead of compare it will not compile and/or it will immediately crash. At least in "common" programming languages ;-)
This web tells little bit more about it - http://united-coders.com/christian-harms/what-are-yoda-conditions/

I started doing that in college when I took my first C++ class in an effort to not accidentally assign a value I was trying to check against, and it's just always followed me. However, when I use C#, I tend to do:
if (var_name.Equals("some_text"))
Not only does this prevent the accidental assignment, but to me, visually, seeing the Equals() is much more understanding than seeing a ==. Just my two cents.

I was taught to write it backwards when I was taking an intro to programming course in college. We were using C++, and as other answers said, it had a difference in C++.

Do you like languages that let you put the "then" before the "if"?

I was reading through some C# code of mine today and found this line:
if (ProgenyList.ItemContainerGenerator.Status != System.Windows.Controls.Primitives.GeneratorStatus.ContainersGenerated) return;
Notice that you can tell without scrolling that it's an "if" statement that works with ItemContainerGenerator.Status, but you can't easily tell that if the "if" clause evaluates to "true" the method will return at that point.
Realistically I should have moved the "return" statement to a line by itself, but it got me thinking about languages that allow the "then" part of the statement first. If C# permitted it, the line could look like this:
return if (ProgenyList.ItemContainerGenerator.Status != System.Windows.Controls.Primitives.GeneratorStatus.ContainersGenerated);
This might be a bit "argumentative", but I'm wondering what people think about this kind of construct. It might serve to make lines like the one above more readable, but it also might be disastrous. Imagine this code:
return 3 if (x > y);
Logically we can only return if x > y, because there's no "else", but part of me looks at that and thinks, "are we still returning if x <= y? If so, what are we returning?"
What do you think of the "then before the if" construct? Does it exist in your language of choice? Do you use it often? Would C# benefit from it?

Let's reformat that a bit and see:
using System.Windows.Controls.Primitives;
...
if (ProgenyList.ItemContainerGenerator.Status != GeneratorStatus.ContainersGenerated)
{
return;
}
Now how hard is it to see the return statement? Admittedly in SO you still need to scroll over to see the whole of the condition, but in an IDE you wouldn't have to... partly due to not trying to put the condition and the result on the same line, and party due to the using directive.
The benefit of the existing C# syntax is that the textual order reflects the execution order - if you want to know what will happen, you read the code from top to bottom.
Personally I'm not a fan of "return if..." - I'd rather reformat code for readability than change the ordering.

I don't like the ambiguity this invites. Consider the following code:
doSomething(x)
if (x > y);
doSomethingElse(y);
What is it doing? Yes, the compiler could figure it out, but it would look pretty confusing for a programmer.

Yes.
It reads better. Ruby has this as part of its syntax - the term being 'statement modifiers'
irb(main):001:0> puts "Yay Ruby!" if 2 == 2
Yay Ruby!
=> nil
irb(main):002:0> puts "Yay Ruby!" if 2 == 3
=> nil
To close, I need to stress that you need to 'use this with discretion'. The ruby idiom is to use this for one-liners. It can be abused - however I guess this falls into the realm of responsible development - don't constrain the better developers by building in restrictions to protect the poor ones.

It's look ugly for me. The existing syntax much better.
if (x > y) return 3;

I think it's probably OK if the scope were limited to just return statements. As I said in my comment, imagine if this were allowed:
{
doSomething();
doSomethingElse();
// 50 lines...
lastThink();
} if (a < b);
But even just allowing it only on return statements is probably a slippery slope. People will ask, "return x if (a); is allowed, so why not something like doSomething() if (a);?" and then you're on your way down the slope :)
I know other languages do get away with it, but C#'s philosophy is more about making The One Right WayTM easy and having more than one way to do something is usually avoided (though with exceptions). Personally, I think it works pretty well, because I can look at someone else's code and know that it's pretty much in the same style that I'd write it in.

I don't see any problem with
return 3 if (x > y);
It probably bothers you because you are not accustomed to the syntax. It is also nice to be able to say
return 3 unless y <= x
This is a nice syntax option, but I don't think that c# needs it.

I think Larry Wall was very smart when he put this feature into Perl. The idea is that you want to put the most important part at the beginning where it's easy to see. If you have a short statement (i.e. not a compound statement), you can put it before the if/while/etc. If you have a long (i.e. compound) statement, it goes in braces after the condition.

Personally I like languages that let me choose.
That said, if you refactor as well as reformat, it probably doesn't matter what style you use, because they will be equally readable:
using System.Windows.Controls.Primitives;
...
var isContainersGenerated =
ProgenyList.ItemContainerGenerator.Status == GeneratorStatus.ContainersGenerated;
if (!isContainersGenerated) return;
//alternatively
return if (!isContainersGenerated);

There is a concern reading the code that you think a statement will execute only later to find out it might execute.
For example if you read "doSomething(x)", you're thinking "okay so this calls doSomething(x)" but then you read the "if" after it and have to realise that the previous call is conditional on the if statement.
When the "if" is first you know immediately that the following code might happen and can treat it as such.
We tend to read sequentially, so reading and going in your mind "the following might happen" is a lot easier than reading and then realising everything you just read needs to be reparsed and that you need to evaluate everything to see if it's within the scope of your new if statement.

Both Perl and Ruby have this and it works fine. Personally I'm fine with as much functionality you want to throw at me. The more choices I have to write my code the better the overall quality, right? "The right tool for the job" and all that.
Realistically though, it's kind of a moot point since it's pretty late for such a fundamental addition in C#'s lifecycle. We're at the point where any minor syntax change would take a lot of work to implement due to the size of the compiler code and its syntax parsing algorithm. For a new addition to be even considered it would have to bring quite a bit of functionality, and this is just a (not so) different way of saying the same thing.

Humans read beginning to end. In analyzing code flow, limits of the short term memory make it more difficult to read postfix conditions due to additional backtracking required. For short expressions, this may not be a problem, but for longer expressions it will incur significant overhead for users that are not seasoned in the language they are reading.

Agreed with confusing , I never heard about this construction before , so I think correct way using then before if must always contents the result of else, like
return (x > y) ? 3 : null;
else way there is no point of using Imperative constructions like
return 3 if (x > y);
return 4 if (x = y);
return 5 if (x < y);
imho It's kinda weird, because I have no idea where to use it...

It's like a lot of things really, it makes perfect sense when you use it in a limited context(a one liner), and makes absolutely no sense if you use it anywhere else.
The problem with that of course is that it'd be almost impossible to restrict the use to where it makes sense, and allowing its use where it doesn't make sense is just odd.
I know that there's a movement coming out of scripting languages to try and minimize the number of lines of code, but when you're talking about a compiled language, readability is really the key and as much as it might offend your sense of style, the 4 line model is clearer than the reversed if.

I think it's a useful construct and a programmer would use it to emphasize what is important in the code and to de-emphasize what is not important. It is about writing intention-revealing code.
I use something like this (in coffeescript):
index = bla.find 'a'
return if index is -1
The most important thing in this code is to get out (return) if nothing is found - notice the words I just used to explain the intention were in the same order as that in the code.
So this construct helps me to code in a way which reflects my intention slightly better.
It shouldn't be too surprising to realize that the order in which correct English or traditional programming-language grammar has typically required, isn't always the most effective or simplest way to create meaning.
Sometimes you need to let everything hang out and truly reassess what is really the best way to do something.

It's considered grammatically incorrect to put the answer before the question, why would it be any different in code?

Go To Statement Considered Harmful?

If the statement above is correct, then why when I use reflector on .Net BCL I see it is used a lot?
EDIT: let me rephrase: are all the GO-TO's I see in reflector written by humans or compilers?

I think the following excerpt from the Wikipedia Article on Goto is particularly relevant here:
Probably the most famous criticism of
GOTO is a 1968 letter by Edsger
Dijkstra called Go To Statement
Considered Harmful. In that letter
Dijkstra argued that unrestricted GOTO
statements should be abolished from
higher-level languages because they
complicated the task of analyzing and
verifying the correctness of programs
(particularly those involving loops).
An alternative viewpoint is presented
in Donald Knuth's Structured
Programming with go to Statements
which analyzes many common programming
tasks and finds that in some of them
GOTO is the optimal language construct
to use.
So, on the one hand we have Edsger Dijkstra (a incredibly talented computer scientist) arguing against the use of the GOTO statement, and specifically arguing against the excessive use of the GOTO statement on the grounds that it is a much less structured way of writing code.
On the other hand, we have Donald Knuth (another incredibly talented computer scientist) arguing that using GOTO, especially using it judiciously can actually be the "best" and most optimal construct for a given piece of program code.
Ultimately, IMHO, I believe both men are correct. Dijkstra is correct in that overuse of the GOTO statement certainly makes a piece of code less readable and less structured, and this is certainly true when viewing computer programming from a purely theoretical perspective.
However, Knuth is also correct as, in the "real world", where one must take a pragmatic approach, the GOTO statement when used wisely can indeed be the best choice of language construct to use.

The above isn't really correct - it was a polemical device used by Dijkstra at a time when gotos were about the only flow control structure in use. In fact, several people have produced rebuttals, including Knuth's classic "Structured Programming Using Goto" paper (title from memory). And there are some situations (error handling, state machines) where gotos can produce clearer code (IMHO), than the "structured" alternatives.

These goto's are very often generated by the compiler, especially inside enumerators.
The compiler always knows what she's doing.
If you find yourself in the need to use goto, you should make sure it is the only option. Most often you'll find there's a better solution.
Other than that, there are very few instances the use of goto can be justified, such as when using nested loops. Again, there are other options in this case still. You could break out the inner loop in a function and use a return statement instead. You need to look closely if the additional method call is really too costly.
In response to your edit:
No, not all gotos are compiler generated, but a lot of them result from compiler generated state machines (enumerators), switch case statements or optimized if else structures. There are only a few instances you'll be able to judge whether it was the compiler or the original developer. You can get a good hint by looking at the function/class name, a compiler will generate "forbidden" names to avoid name clashes with your code. If everything looks normal and the code has not been optimized or obfuscated the use of goto is probably intended.

Keep in mind that the code you are seeing in Reflector is a disassembly -- Reflector is looking at the compiled byte codes and trying to piece together the original source code.
With that, you must remember that rules against gotos apply to high-level code. All the constructs that are used to replace gotos (for, while, break, switch etc) all compile down to code using JMPs.
So, Reflector looks at code much like this:
A:
if !(a > b)
goto B;
DoStuff();
goto A;
B: ...
And must realize that it was actually coded as:
while (a > b)
DoStuff();
Sometimes the code being read to too complicated for it to recognize the pattern.

Go To statement itself is not harmful, it is even pretty useful sometimes. Harmful are users who tend to put it in inappropriate places in their code.

When compiled down to assembly code, all control structured and converted to (un)conditional jumps. However, the optimizer may be too powerful, and when the disassembler cannot identify what control structure a jump pattern corresponds to, the always-correct statement, i.e. goto label; will be emitted.
This has nothing to do with the harm(ful|less)ness of goto.

what about a double loop or many nested loops, of which you have break out, for ex.
foreach (KeyValuePair<DateTime, ChangedValues> changedValForDate in _changedValForDates)
{
foreach (KeyValuePair<string, int> TypVal in changedValForDate.Value.TypeVales)
{
RefreshProgress("Daten werden geändert...", count++, false);
if (IsProgressCanceled)
{
goto TheEnd; //I like goto :)
}
}
}
TheEnd:
in this case you should consider that here the following should be done with break:
foreach(KeyValuePair<DateTime, ChangedValues> changedValForDate in _changedValForDates)
{
foreach (KeyValuePair<string, int> TypVal in changedValForDate.Value.TypeVales)
{
RefreshProgress("Daten werden geändert...", count++, false);
if (IsProgressCanceled)
{
break; //I miss goto :|
}
}
if (IsProgressCanceled)
{
break; //I really miss goto now :|
}//waaaAA !! so many brakets, I hate'm
}

The general rule is that you don't need to use goto. As with any rule there are of course exceptions, but as with any exceptions they are few.
The goto command is like a drug. If it's used in limited amounts only in special situations, it's good. If you use too much all the time, it will ruin your life.
When you are looing at the code using Reflector, you are not seeing the actual code. You are seeing code that is recreated from what the compiler produced from the original code. When you see a goto in the recreated code, it's not certain that there was a goto in the original code. There might be a more structured command to control the flow, like a break or a continue which has been implemented by the compiler in the same way as a goto, so that Reflector can't tell the difference.

goto considered harmful (for human to use but
for computers its okay).
because no matter how madly we(human) use goto, compiler always knows how to read the code.
Believe me...
Reading others code with gotos in it is HARD. Reading your own code with gotos in it is HARDER.
That is why you see it used in low level (machine languages) and not in high level (human languages e.g. C#,Python...) ;)

"C provides the infinitely-abusable goto statement, and labels to branch to. Formally, the goto is never necessary, and in practice it is almost always easy to write code without it. We have not used goto in this book."
-- K&R (2nd Ed.) : Page 65

I sometimes use goto when I want to perform a termination action:
static void DoAction(params int[] args)
{
foreach (int arg in args)
{
Console.WriteLine(arg);
if (arg == 93) goto exit;
}
//edit:
if (args.Length > 3) goto exit;
//Do another gazillion actions you might wanna skip.
//etc.
//etc.
exit:
Console.Write("Delete resource or whatever");
}
So instead of hitting return, I send it to the last line that performs another final action I can refer to from various places in the snippet instead of just terminating.

In decompiled code, virtually all gotos that you see will be synthetic. Don't worry about them; they're an artifact of how the code is represented at the low level.
As to valid reasons for putting them in your own code? The main one I can think of is where the language you are using does not provide a control construct suitable for the problem you are tackling; languages which make it easy to make custom control flow systems typically don't have goto at all. It's also always possible to avoid using them at all, but rearranging arbitrarily complex code into a while loop and lots of conditionals with a whole battery of control variables... that can actually make the code even more obscure (and slower too; compilers usually aren't smart enough to pick apart such complexity). The main goal of programming should be to produce a description of a program that is both clear to the computer and to the people reading it.

If it's harmful or not, it's a matter of likes and dislikes of each one. I personally don't like them, and find them very unproductive as they attempt maintainability of the code.
Now, one thing is how gotos affect our reading of the code, while another is how the jitter performs when found one. From Eric Lippert's Blog, I'd like to quote:
We first run a pass to transform loops into gotos and labels.
So, in fact the compiler transforms pretty each flow control structure into goto/label pattern while emitting IL. When reflector reads the IL of the assembly, it recognizes the pattern, and transforms it back to the appropriate flow control structure.
In some cases, when the emitted code is too complicated for reflector to understand, it just shows you the C# code that uses labels and gotos, equivalent to the IL it's reading. This is the case for example when implementing IEnumerable<T> methods with yield return and yield break statements. Those kind of methods get transformed into their own classes implementing the IEnumerable<T> interface using an underlying state machine. I believe in BCL you'll find lots of this cases.

GOTO can be useful, if it's not overused as stated above. Microsoft even uses it in several instances within the .NET Framework itself.

These goto's are very often generated by the compiler, especially inside enumerators. The compiler always knows what she's doing.
If you find yourself in the need to use goto, you should make sure it is the only option. Most often you'll find there's a better solution.
Other than that, there are very few instances the use of goto can be justified, such as when using nested loops. Again, there are other options in this case still. You could break out the inner loop in a function and use a return statement instead. You need to look closely if the additional method call is really too costly.

Is Resharper correct?

I just installed Reshaper 4.5 and it has come up with the following suggestions:
return this.GetRuleViolations().Count() == 0; -- REMOVE this.
new string[] { this.ID.ToString(), this.Registration } -- REMOVE string, MAKE ANONYMOUS TYPE
int i = Method.GetNumber(); -- REPLACE int WITH var
Should I do these?
I think in some cases it is going to make the code less readable but will it improve performance? what are the benefits of making these changes?
Thanks

1) The explicit this pointer is only necessary when the reference would otherwise be ambiguous. Since GetRuleViolations is defined on the type, you most likely do not need this.
Another point here is that if GetRuleViolations return an IEnumerable of something, you will generally be much better off using Any() instead of Count() == 0 as you risk enumerating the entire sequence.
2) String can be inferred from the initialization.
3) Resharper prefers var over specific types.

Apart from the obvious benefit of your little square going green, if you are writing code that will be maintained by someone else later, it makes good sense not to use your personal preference in coding syntax. Resharper is becoming useful in formatting code in a way that is recognisable to a very wide audience.
I belong to the school of thought that says it doesn't matter who's way is right. If we all stick to a pattern, we'll all find it easier to read each others code.
So, in my humble opinion, don't change the default resharper settings. Just accept that if you use the defaults, you make life simple for everyone.

I think the first one is for the purpose, if you want to make "GetRuleViolations()" a static method. Then you have not to remove the "this" identifier.

For the 3rd one - the one that annoys me the most. It provides the reader with less information and i think it's just a matter of showing off a newish feature.
I'd say - use var when you know the return type and use the correct object type when you do not like this:
var reader = new XmlReader(.... // Implicit
XmlReader reader = SomeClass.GetReader() // Explicit when you can't be sure

First one: Resharper is asking about removing this which is just a style thing to me. Nothing more, keeping it won't harm performance in any way. It is just a matter of readability.
For second and third: Resharper normally prefers using var instead of specific data type, that's why the suggestions. I believe it is a matter of personal choice and provides no extra gain other than readability.

The first seems unclear to me. You usually don't have to prefix this. as long as there are no ambiguities, which I cannot tell from this example. Resharper is probably right. The other two won't improve performance, the compiled result will be the same. It's just a matter of taste and, of course, your coding guidelines.

The first one should be configurable. As far as I remember, you can tell ReSharper whether you want to have "this." in front of only fields, methods, both or none.
Using "var" will not change anything in the generated CIL code, so the performance will stay the same. I haven't used ReSharper for some time and I don't know why it promotes anonymous types so aggressively, but one advantage of "var" is that it's more resistant to change.
Meaning if, instead of calling Method.GetNumber(), you called a wrapper, eg. Filter(Method.GetNumber()) in the same line that returns a Nullable, you won't have to update the variable's type.

None of these will have any effect on performance, only on readability.
I find suggestions 1 and 2 to be more readable, and 3 less readable than your original code.
But you don't need to just follow these suggestions if, e.g., you find them less readable or if they violate your company's code style standard. When you put the cursor on the squiggly line, press Alt-Enter to show the list of Contex Actions. One of them will be to to change the severity of the inspection; you can not show it at all or show it as a hint. You can find a complete list of inspections at ReSharper | Options | Code Inspection | Inspection Severity.