I have a object that I want to print it into string [key1=value1&key2=value2...etc] without the null value key value pair and comma into &.
So first of all i think of putting it into a map but it won't work and I don know how it work either.
val wxPayOrderObj = WxPayOrder(appid = "wx0b6dcsad20b379f1", mch_id =
"1508334851", nonce_str = UUID.randomUUID().toString(),sign = null,
body = "QQTopUp", out_trade_no = "20150806125346", total_fee = req.total_fee,
spbill_create_ip = "123.12.12.123",
trade_type = "JSAPI", openid = "oUpF8uMuAJO_M2pxb1Q9zNjWeS6o")
so the output will be
appid=wx0b6dc78d20b379f1&mch_id=150788851&nonce_str=UUID.randomUUID().toString()&
body=QQTopUp&out_trade_no=20150806125346&total_fee=req.total_fee&
spbill_create_ip=123.12.12.123&trade_type=JSAPI&openid=oUpF8uMuAJO_M2pxb1Q9zNjWeS6o
anyone please help me, thanks in advances.
I don't really get your question, but you want to convert object to string (to a format that you want)?
Override the object's toString() to return "[key1=value1&key2=value2...etc]"
example
override fun toString(){
// make sure you compute the data first
val answer = "[key1=$value1&key2=$value2...etc]"
return answer
}
The $ is used in string templates (That's directly writing the name of a variable, the value will be used later to be concatenated) with other strings)
Related
Is there an easier approach to convert an Intellij IDEA environment variable into a list of Tuples?
My environment variable for Intellij is
GROCERY_LIST=[("egg", "dairy"),("chicken", "meat"),("apple", "fruit")]
The environment variable gets accessed into Kotlin file as String.
val g_list = System.getenv("GROCERY_LIST")
Ideally I'd like to iterate over g_list, first element being ("egg", "dairy") and so on.
And then ("egg", "dairy") is a tuple/pair
I have tried to split g_list by comma that's NOT inside quotes i.e
val splitted_list = g_list.split(",(?=(?:[^\\\"]*\\\"[^\\\"]*\\\")*[^\\\"]*\$)".toRegex()).toTypedArray()
this gives me first element as [("egg", second element as "dairy")] and so on.
Also created a data class and tried to map the string into data class using jacksonObjectMapper following this link:
val mapper = jacksonObjectMapper()
val g_list = System.getenv("GROCERY_LIST")
val myList: List<Shopping> = mapper.readValue(g_list)
data class Shopping(val a: String, val b: String)
You can create a regular expression to match all strings in your environmental variable.
Regex::findAll()
Then loop through the strings while creating a list of Shopping objects.
// Raw data set.
val groceryList: String = "[(\"egg\", \"dairy\"),(\"chicken\", \"meat\"),(\"apple\", \"fruit\")]"
// Build regular expression.
val regex = Regex("\"([\\s\\S]+?)\"")
val matchResult = regex.findAll(groceryList)
val iterator = matchResult.iterator()
// Create a List of `Shopping` objects.
var first: String = "";
var second: String = "";
val shoppingList = mutableListOf<Shopping>()
var i = 0;
while (iterator.hasNext()) {
val value = iterator.next().value;
if (i % 2 == 0) {
first = value;
} else {
second = value;
shoppingList.add(Shopping(first, second))
first = ""
second = ""
}
i++
}
// Print Shopping List.
for (s in shoppingList) {
println(s)
}
// Output.
/*
Shopping(a="egg", b="dairy")
Shopping(a="chicken", b="meat")
Shopping(a="apple", b="fruit")
*/
data class Shopping(val a: String, val b: String)
Never a good idea to use regex to match parenthesis.
I would suggest a step-by-step approach:
You could first match the name and the value by
(\w+)=(.*)
There you get the name in group 1 and the value in group 2 without caring about any subsequent = characters that might appear in the value.
If you then want to split the value, I would get rid of start and end parenthesis first by matching by
(?<=\[\().*(?=\)\])
(or simply cut off the first and last two characters of the string, if it is always given it starts with [( and ends in )])
Then get the single list entries from splitting by
\),\(
(take care that the split operation also takes a regex, so you have to escape it)
And for each list entry you could split that simply by
,\s*
or, if you want the quote character to be removed, use a match with
\"(.*)\",\s*\"(.*)\"
where group 1 contains the key (left of equals sign) and group 2 the value (right of equals sign)
I want to fill two variables in the same line, but I don't know the best way to do it at kotlin
var a:String? = null
var b:String? = null
a, b = "Text"
Not possible in Kotlin (unless you are ready to resort to some contrived constructs with repetition as described in other answers and comments). You cannot even write
a = b = "Text"
because weirdly enough, assignments are not expressions in Kotlin (as opposed to almost everything else like if, return, throw, swicth, etc., which are expressions in Kotlin, but not in Java, for example).
So, if you want to assign exactly the same value without repetition (of the assigned value), you'll have to write
a = "Text"
b = a
Note, that there is also an also function (pun intended), so technically you can write the following if you really want to stay on one line
a = "Text".also { b = it }
but I doubt it is really worth it.
var a: String? = null; var b: String? = null
or
var (a: String?, b: String?) = null to null
But please don't ever do so
Simply create an inline array, iterate through and assign values.
arrayListOf(a, b, c, d).forEach { it = "Text" }
I have been looking for a solution everywhere on the internet but nowhere I can see a single script which lets me read the name of a variable as a string in Godot 3.1
What I want to do:
Save path names as variables.
Compare the name of the path variable as a string to the value of another string and print the path value.
Eg -
var Apple = "mypath/folder/apple.png"
var myArray = ["Apple", "Pear"]
Function that compares the Variable name as String to the String -
if (myArray[myposition] == **the required function that outputs variable name as String**(Apple) :
print (Apple) #this prints out the path.
Thanks in advance!
I think your approach here might be a little oversimplified for what you're trying to accomplish. It basically seems to work out to if (array[apple]) == apple then apple, which doesn't really solve a programmatic problem. More complexity seems required.
First, you might have a function to return all of your icon names, something like this.
func get_avatar_names():
var avatar_names = []
var folder_path = "res://my/path"
var avatar_dir = Directory.new()
avatar_dir.open(folder_path)
avatar_dir.list_dir_begin(true, true)
while true:
var avatar_file = avatar_dir.get_next()
if avatar_file == "":
break
else:
var avatar_name = avatar_file.trim_suffix(".png")
avatar_names.append(avatar_name)
return avatar_names
Then something like this back in the main function, where you have your list of names you care about at the moment, and for each name, check the list of avatar names, and if you have a match, reconstruct the path and do other work:
var some_names = ["Jim","Apple","Sally"]
var avatar_names = get_avatar_names()
for name in some_names:
if avatar_names.has(name):
var img_path = "res://my/path/" + name + ".png"
# load images, additional work, etc...
That's the approach I would take here, hope this makes sense and helps.
I think the current answer is best for the approach you desire, but the performance is pretty bad with string comparisons.
I would suggest adding an enumeration for efficient comparisons. unfortunately Godot does enums differently then this, it seems like your position is an int so we can define a dictionary like this to search for the index and print it out with the int value.
var fruits = {0:"Apple",1:"Pear"}
func myfunc():
var myposition = 0
if fruits.has(myposition):
print(fruits[myposition])
output: Apple
If your position was string based then an enum could be used with slightly less typing and different considerations.
reference: https://docs.godotengine.org/en/latest/tutorials/scripting/gdscript/gdscript_basics.html#enums
Can't you just use the str() function to convert any data type to stirng?
var = str(var)
I have a Front-End application that sends me Data to update my User (updatedUser). Since I don't want to send the whole Userdata, I'm only sending the data that has changed. Now I want to Update my Userdata with the changes provided, so I'd like to know if there is a more elegant way to do this than just a list of ifs/lets. I'm quite new to kotlin, so don't expect too much from me^^
Not so elegant way:
changeData.firstname?.let { updatedUser.firstname = it }
changeData.lastname?.let { updatedUser.lastname = it }
...
Expected (doesn't work - type mismatch):
updatedUser.copy(
firstname = changeData?.firstname,
lastname = changeData?.lastname,
...)
the reason you get a type mismatch is There is a string type and a string nullable type
var variableName:String = "myData" // if you want a non nullable
var variableName:String? = "myDataThatCouldBeNull" // if you want a string that could be null
I would like to swap a string from "abcde" to "bcdea". So I wrote my code as below in Kotlin
var prevResult = "abcde"
var tmp = prevResult[0]
for (i in 0..prevResult.length - 2) {
prevResult[i] = prevResult[i+1] // Error on preveResult[i]
}
prevResult[prevResult.length-1] = tmp // Error on preveResult[prevResult.lengt-1]
It errors out as stated above comment line. What did I do wrong? How could I fix this and get what I want?
Strings in Kotlin just like in Java are immutable, so there is no string.set(index, value) (which is what string[index] = value is equivalent to).
To build a string from pieces you could use a StringBuilder, construct a CharSequence and use joinToString, operate on a plain array (char[]) or do result = result + nextCharacter (creates a new String each time -- this is the most expensive way).
Here's how you could do this with StringBuilder:
var prevResult = "abcde"
var tmp = prevResult[0]
var builder = StringBuilder()
for (i in 0..prevResult.length - 2) {
builder.append(prevResult[i+1])
}
builder.append(tmp) // Don't really need tmp, use prevResult[0] instead.
var result = builder.toString()
However, a much simpler way to achieve your goal ("bcdea" from "abcde") is to just "move" one character:
var result = prevResult.substring(1) + prevResult[0]
or using the Sequence methods:
var result = prevResult.drop(1) + prevResult.take(1)
You can use drop(1) and first() (or take(1)) to do it in one line:
val str = "abcde"
val r1 = str.drop(1) + str.first()
val r2 = str.drop(1) + str.take(1)
As to your code, Kotlin String is immutable and you cannot modify its characters. To achieve what you want, you can convert a String to CharArray, modify it and then make a new String of it:
val r1 = str.toCharArray().let {
for (i in 0..it.lastIndex - 1)
it[i] = it[i+1]
it[it.lastIndex] = str[0] // str is unchanged
String(it)
}
(let is used for conciseness to avoid creating more variables)
Also, you can write a more general version of this operation as an extension function for String:
fun String.rotate(n: Int) = drop(n % length) + take(n % length)
Usage:
val str = "abcde"
val r1 = str.rotate(1)
Simpler solution: Just use toMutableList() to create a MutableList of Char and then join it all together with joinToString.
Example:
Given a String input, we want to exchange characters at positions posA and posB:
val chars = input.toMutableList()
val temp = chars[posA]
chars[posA] = chars[posB]
chars[posB] = temp
return chars.joinToString(separator = "")
Since Strings are immutable, you will have to copy the source string into an array, make changes to the array, then create a new string from the modified array. Look into:
getChars() to copy the string chars into an array.
Perform your algorithm on that array, making changes to it as needed.
Convert the modified array back into a String with String(char[]).