Develop Reference

Remove certain element from array in Velocity Template Language (VTL)

I would like to remove a certain element from an array in Velocity Template Language. I did not find any appropriate method looking through the documentation of Apache VTL, that's why I am asking here for help. I have tried following (.remove() doesn't seem to be a method on array items):
#set($linkedWIARRAY = ["ABC-123, DEF-345, GHI-678"])
#set($dummy=$linkedWIARRAY.add("JKL-901"))
#set($dummy = $linkedWIARRAY.remove("DEF-345"))
$linkedWIARRAY
$linkedWIARRAY returns [ABC-123, DEF-345, GHI-678, JKL-901], showing that remove very likely doesn't exist as method on arrays ;)
There is a similar question on SO, that didn't help me:
velocity template drop element from array

The problem lies in the initialization of the list. It should be:
#set($linkedWIARRAY = ["ABC-123", "DEF-345", "GHI-678"])
that is, each string should be enclosed in double quotes, not the whole string.

Parsing a string into different variable types

Relatively new to programming here so I apologize if this is rather basic.
I am trying to convert string lines into actual variables of different types.
My input is a file in the following format:
double d1, d2 = 3.14, d3;
int a, b = 17, c, g;
global int gInt = 1;
final int fInt = 2;
String s1, s2 = "Still with me?", s3;
These lines are all strings at this point. I wish to extract the variables from the strings and receive the actual variables so I can use and manipulate them.
So far I've tried using regex but I'm stumbling here. Would love some direction as to how this is possible.
I thought of making a general type format for example:
public class IntType{
boolean finalFlag;
boolean globalFlag;
String variableName;
IntType(String variableName, boolean finalFlag, boolean globalFlag){
this.finalflag = finalFlag;
this.globalFlag = globalFlag;
this.variableName = variableName;
}
}
Creating a new wrapper for each of the variable types.
By using and manipulating I would like to then compare between the wrappers I've created and check for duplicate declarations etc'.
But I don't know if I'm on the right path.
Note: Disregard bad format (i.e. no ";" at the end and so on)

While others said that this is not possible, it actually is. However it goes somewhat deep into Java. Just search for java dynamic classloading. For example here:
Method to dynamically load java class files
It allows you do dynamically load a java file at runtime. However your current input does not look like a java file but it can easily be converted to one by wrapping it with a small wrapper class like:
public class CodeWrapper() {
// Insert code from file here
}
You can do this with easy file or text manipulations before loading the ressource as class.
After you have loaded the class you can access its variables via reflection, for example by
Field[] fields = myClassObject.getClass().getFields();
This allows you to access the visibility modifier, the type of the variable, the name, the content and more.
Of course this approach presumes that your code actually is valid java code.
If it is not and you are trying to confirm if it is, you can try to load it. If it fails, it was non-valid.

I have no experience with Java, but as far as my knowledge serves me, it is not possible to actually create variables using a file in any language. You'll want to create some sort of list object which can hold a variable amount of items of a certain type. Then you can read the values from a file, parse them to the type you want it to be, and then save it to the list of the corresponding type.
EDIT:
If I were you, I would change my file layout if possible. It would then look something like this:
1 2 3 4 //1 int, 2 floats, 3 booleans and 4 strings
53
3.14
2.8272
true
false
false
#etc.
In pseudo code, you would then read it as follows:
string[] input = file.Readline().split(' '); // Read the first line and split on the space character
int[] integers = new int[int.Parse(input[0])] // initialise an array with specefied elements
// Make an array for floats and booleans and strings the same way
while(not file.eof) // While you have not reached the end of the file
{
integers.insert(int.Parse(file.ReadLine())) // parse your values according to the size which was given on the first line of the file
}
If you can not change the file layout, then you'll have to do some smart string splitting to extract the values from the file and then create some sort of dynamic array which resizes as you add more values to it.
MORE EDITS:
Based on your comment:
You'll want to split on the '=' character first. From the first half of the split, you'll want to search for a type and from the second half, you can split again on the ',' to find all the values.

The difference between arrays in Java and C

In my book there is an example which explains the differences between arrays in Java and C.
In Java we can create an array by writing:
int[] a = new int[5];
This just allocates storage space on the stack for five integers and we can access them exactly as we would have done in Java
int a[5] = {0};
int i;
for (i = 0, i < 5; i++){
printf("%2d: %7d\n", i, a[i]);
}
Then the author says the following
Of course our program should not use a number 5 as we did on several places in the example, instead we use a constant. We can use the C preprocessor to do this:
#define SIZE 5
What are advantages of defining a constant SIZE 5?

Using a named constant is generally considered good practice because if it is used in multiple places, you only need to change the definition to change the value, rather than change every occurrence - which is error prone.
For example, as mentioned by stark in the comments, it is likely that you'll want to loop over an array. If the size of the array is defined by a named constant called SIZE, then you can use that in the loop bounds. Changing the size of the array then only requires changing the definition of SIZE.
There is also the question of whether #define is really the right solution.
To borrow another comment, from Jonathan Leffer: see static const vs #define vs enum for a discussion of different ways of naming constants. While modern C does allow using a variable as an array size specifier, this technically results in a variable-length array which may incur a small overhead.

You should use a constant, because embedding magic numbers in code makes it harder to read and maintain. For instance, if you see 52 in some code, you don't know what it is. However, if you write #define DECKSIZE 52, then whenever you see DECKSIZE, you know exactly what it means. In addition, if you want to change the deck size, say 36 for durak, you could simply change one line, instead of changing every instance throughout the code base.

Well, imagine that you create a static array of 5 integer just like you did int my_arr [5]; ,you code a whole programm with it, but.. suddenly you realise that maybe you need more space. Imagine that you wrote a code of 6-700 lines, you MUST replace every occurence of you array with the fixed number of your choice. Every for loop, and everything that is related with the size of this array. You can avoid all of this using the preprocessor command #define which will replace every occurence of a "keyword" with the content you want, it's like a synonymous for something. Eg: #define SIZE 5 will replace in your code every occurence of the word SIZE with the value 5.

I find comments here to be superflous. As long as you use your constant (5 in this case) only once, it doesn't matter where it is. Moreover, having it in place improves readability. And you certainly do not need to use the constant in more than one place - afterall, you should infer the size of array through sizeof operator anyways. The benefit of sizeof approach is that it works seamlessly with VLAs.
The drawback of global #define (or any other global name) is that it pollutes global namespace. One should understand that global names is a resource to be used conservatively.

#define SIZE 5
This looks like an old outdated way of declaring constants in C code that was popular in dinosaur era. I suppose some lovers of this style are still alive.
The preferred way to declare constants in C languages nowadays is:
const int kSize = 5;

cordova.exec strange behaviour in parameters

Using cordova 2.6, i am calling a plugin using cordova.exec.
The issue is that the parameters if passed in an array element are being cut(truncated from the end by some characters) at the java side.
but if i pass a simple string as a parameter its being passed perfectly fine.
Passed 5714 characters in string and its going without any isues, but passing 450 characters in an array's first element is cutting the array into about 1/4th of its original length(119) .
Then tried the following :
Converted the first array element into string.(Checked the typeof using javascript) and passed but did not help.
Created a substring of the original array and passed static limits to the substring i.e substring(0,4000) etc etc, but to no luck.
Made a clone of the original array and repeated steps 1 and 2 but again no luck.
Could someone tell me where the issue is?
Increased eclipse heap memory and changed to cordova 2.8.1 too, but the same result. :(

I got the reason for the behaviour. Inspected many images , and in my execute method of plugin did the following :
int myLength = args.getString(0).length();
Log.v(TAG,Character.toString(args.getString(0).charAt(myLength-1)));
Got the character as = on the plugin/java side. And an = is inserted in the base64 string at the end of it. It seems that cordova is inserting these delimeters in the base64string.
P.S. :Went through phonegap.js and found that the arguments are being packed as JSON.stringify , and after that could not get more. That how and where the = is inserted.

Java Byte[] to String conversion dropping end quotes / weird side-effect

I am currently trying to perform some regex on the result of a DatagramPacket.getData() call.
Implemented as String myString = new String(thepkt.getData()):
But weirdly, java is dropping the end quotation that it uses to encapsulate all data(see linked image below).
When I click the field in the variable inspector during a debug session and don't change anything, when I click off the variable field it corrects itself again without me changing anything. It even highlights the variable inspection field in yellow to signal change.
Its values are also displaying like it is still a byte array rather than a String object
http://i.imgur.com/8ZItsZI.png
It's throwing off my regex and I can't see anything that would cause it. It's a client server simulation and on the client side, the getData returns the data no problem.

I got it working by using the solution provided in:
https://stackoverflow.com/a/8557165/1700855
But I still don't understand how not specifying the length of the packet to the String constructor would cause it to drop the systematic end double quotes. Can anyone provide an explanation as I really like to understand solutions to my issues before moving on :)

The problem is that you didn't read the spec for DatagramPacket.getData:
Returns the data buffer. The data received or the data to be sent
starts from the offset in the buffer, and runs for length long.
So, to be correct, you should use
new String(thepkt.getData(), thepkt.getOffset(), thepht.getLength())
Or, to not use the default charset:
new String(thepkt.getData(), thepkt.getOffset(), thepht.getLength(), someCharset)