Develop Reference

How to count the number of string characters in Kotlin?

#SuppressLint("SetTextI18n")
private fun countName(x: String) {
val textView: TextView = findViewById(R.id.result)
for (i in 0 until x.length) {
textView.text = i.toString()
}
}
This is what I have so far. It works somewhat but for some reason it is lagging behind 1 number. For example, if I type James, the number it will output would be 4.

How to get the number of characters in a string (usually what you want):
str.length
How to get the number of Unicode code points in a string (because sometimes a code point is encoded as multiple characters):
str.codePointCount(0, str.length)
See this Java answer for more details on the difference between these two options.

There are many simple ways to get the number of characters in a string. but if you want to know the mistake in your code you should have started to count from 1 instead of 0.
for (i in 1 until x.length) {
textView.text = i.toString()
}

Android Get Country Emoji Flag Using Locale

I have seen that since Lollipop, Android has built in Emoji flags for different countries. Is it possible to use the devices locale to retrieve the Emoji flag for that country?
I wanted to insert the Emoji flag into a TextView which contains the user's location.

Emoji is a Unicode symbols. Based on the Unicode character table Emoji flags consist of 26 alphabetic Unicode characters (A-Z) intended to be used to encode ISO 3166-1 alpha-2 two-letter country codes (wiki).
That means it is possible to split two-letter country code and convert each A-Z letter to regional indicator symbol letter:
private String localeToEmoji(Locale locale) {
String countryCode = locale.getCountry();
int firstLetter = Character.codePointAt(countryCode, 0) - 0x41 + 0x1F1E6;
int secondLetter = Character.codePointAt(countryCode, 1) - 0x41 + 0x1F1E6;
return new String(Character.toChars(firstLetter)) + new String(Character.toChars(secondLetter));
}
Or in Kotlin, for example (assuming UTF-8):
val Locale.flagEmoji: String
get() {
val firstLetter = Character.codePointAt(country, 0) - 0x41 + 0x1F1E6
val secondLetter = Character.codePointAt(country, 1) - 0x41 + 0x1F1E6
return String(Character.toChars(firstLetter)) + String(Character.toChars(secondLetter))
}
Where 0x41 represents uppercase A letter and 0x1F1E6 is REGIONAL INDICATOR SYMBOL LETTER A in the Unicode table.
Note: This code example is simplified and doesn't have required checks related to country code, that could be not available inside the locale.

Based on this answer, I wrote a Kotlin version below using extension function.
I also added some checks to handle unknown country code.
/**
* This method is to change the country code like "us" into 🇺🇸
* Stolen from https://stackoverflow.com/a/35849652/75579
* 1. It first checks if the string consists of only 2 characters: ISO 3166-1 alpha-2 two-letter country codes (https://en.wikipedia.org/wiki/Regional_Indicator_Symbol).
* 2. It then checks if both characters are alphabet
* do nothing if it doesn't fulfil the 2 checks
* caveat: if you enter an invalid 2 letter country code, say "XX", it will pass the 2 checks, and it will return unknown result
*/
fun String.toFlagEmoji(): String {
// 1. It first checks if the string consists of only 2 characters: ISO 3166-1 alpha-2 two-letter country codes (https://en.wikipedia.org/wiki/Regional_Indicator_Symbol).
if (this.length != 2) {
return this
}
val countryCodeCaps = this.toUpperCase() // upper case is important because we are calculating offset
val firstLetter = Character.codePointAt(countryCodeCaps, 0) - 0x41 + 0x1F1E6
val secondLetter = Character.codePointAt(countryCodeCaps, 1) - 0x41 + 0x1F1E6
// 2. It then checks if both characters are alphabet
if (!countryCodeCaps[0].isLetter() || !countryCodeCaps[1].isLetter()) {
return this
}
return String(Character.toChars(firstLetter)) + String(Character.toChars(secondLetter))
}
Runnable Code Snippet
I also included a runnable Kotlin snippet using Kotlin Playground. In order to run the snippet you need to:
click "Show code snippet"
click "Run Code Snippet"
click the play button at the right top of the generated console
scroll to the bottom to see the result (it's hidden..)
<script src="https://unpkg.com/kotlin-playground#1.6.0/dist/playground.min.js" data-selector=".code"></script>
<div class="code" style="display:none;">
/**
* This method is to change the country code like "us" into 🇺🇸
* Stolen from https://stackoverflow.com/a/35849652/75579
* 1. It first checks if the string consists of only 2 characters: ISO 3166-1 alpha-2 two-letter country codes (https://en.wikipedia.org/wiki/Regional_Indicator_Symbol).
* 2. It then checks if both characters are alphabet
* do nothing if it doesn't fulfil the 2 checks
* caveat: if you enter an invalid 2 letter country code, say "XX", it will pass the 2 checks, and it will return unknown result
*/
fun String.toFlagEmoji(): String {
// 1. It first checks if the string consists of only 2 characters: ISO 3166-1 alpha-2 two-letter country codes (https://en.wikipedia.org/wiki/Regional_Indicator_Symbol).
if (this.length != 2) {
return this
}
val countryCodeCaps = this.toUpperCase() // upper case is important because we are calculating offset
val firstLetter = Character.codePointAt(countryCodeCaps, 0) - 0x41 + 0x1F1E6
val secondLetter = Character.codePointAt(countryCodeCaps, 1) - 0x41 + 0x1F1E6
// 2. It then checks if both characters are alphabet
if (!countryCodeCaps[0].isLetter() || !countryCodeCaps[1].isLetter()) {
return this
}
return String(Character.toChars(firstLetter)) + String(Character.toChars(secondLetter))
}
fun main(args: Array<String>){
println("us".toFlagEmoji())
println("AF".toFlagEmoji())
println("BR".toFlagEmoji())
println("MY".toFlagEmoji())
println("JP".toFlagEmoji())
}
</div>

When I first wrote this answer I somehow overlooked that I've only worked on Android via React Native!
Anyway, here's my JavaScript solution that works with or without ES6 support.
function countryCodeToFlagEmoji(country) {
return typeof String.fromCodePoint === "function"
? String.fromCodePoint(...[...country].map(c => c.charCodeAt() + 0x1f185))
: [...country]
.map(c => "\ud83c" + String.fromCharCode(0xdd85 + c.charCodeAt()))
.join("");
}
console.log(countryCodeToFlagEmoji("au"));
console.log(countryCodeToFlagEmoji("aubdusca"));
If you want to pass in the country codes as capital letters instead, just change the two offsets to 0x1f1a5 and 0xdda5.

You can get the country code very simple.
I want to talk about flag selection according to country code.
I wrote a class about it and it is very simple to use.
usage:
String countryWithFlag = CountryFlags.getCountryFlagByCountryCode("TR") + " " + "Türkiye";
Output : 🇹🇷 Türkiye
You can use it with Android TextView too :)
You can check out the class here
It works very well on Android 6 and above.

I am using this so easily.
Get the Unicode from here.
For Bangladesh flag it is U+1F1E7 U+1F1E9
Now,
{...
String flag = getEmojiByUnicode(0x1F1E7)+getEmojiByUnicode(0x1F1E9)+ " Bangladesh";
}
public String getEmojiByUnicode(int unicode){
return new String(Character.toChars(unicode));
}
It will show > (Bangladeshi flag) Bangladesh

I was looking for that too but I don't think it's possible yet.
Have a look here:
http://developer.android.com/reference/java/util/Locale.html
No mentioning about flags.
_
Alternately you can check the answer here:
Android Countries list with flags and availability of getting iso mobile codes
that might help you.

Determine if content in editText is a "." ONLY

I have written a calculator type app. My mates found that entering single decimal points only into the editText's makes the app crash. Decimal numbers and integers work fine, but I get a number format exception when .'s are entered.
I want to check if a single . has been placed in an editText, in order for me to display a toast telling the user to stop trying to crash the app.
My issue is that a . doesn't have a numerical value...

You can wrap it in a try/catch which should be done anyway when parsing text. So something like
try
{
int someInt = Integer.parseInt(et.getText().toString());
// other code
}
catch (NumberFormatException e)
{
// notify user with Toast, alert, etc...
}
This way it will protect against any number format exception and will make the code more reusable later on.

You can treat .1 as 0.1 by the following.
String text = et.getText().toString();
int len = text.length();
// Do noting if edit text just contains a "." without numbers
if(len==0 || (len==1 && text.charAt(0).equals(".")))
return;
if(text.charAt(0).equals(".") && text.length() > 1) {
text = "0" + text;
}
// Do your parsing and calculations

How to format a Double value properly with decimal separator?

I have an application that uses thousands separator (,) and decimal separator (.), I used this app on 2 tablets with the same languages (Español) on their configuration and when I do some process with numbers like 15,000.00 on the first one the answer was correct but in the second tablet the number changes to 15,00. I changed the language of the second to English, and it works, but how can i set this number format on code?
Sorry about the errors this is not my native language.
Thanks for the help

You could format a double value in code like this:
/**
* format a number properly
* #param number
* #return
*/
public String formatDecimal(double number) {
DecimalFormat nf = new DecimalFormat("###.###.###.##0,00");
// or this way: nf = new DecimalFormat("###,###,###,##0.00");
String formatted = nf.format(number);
return formatted;
}
And then set it to a TextView:
mytextview.setText("MyDouble: " + formatDecimal(somedouble));

You could format using
NumberFormat nf = NumberFormat.getInstance(new Locale("es", "MX")); //for example
But beware because depending on the locale, even if is the same language but different country the decimal char and grouping char my change, for example
NumberFormat nf = NumberFormat.getInstance(new Locale("es", "CO")); //displays 15.000,00

You can get an instance for a specific locale as specified by the android docs:
NumberFormat nf = NumberFormat.getInstance(Locale.FRENCH);
However, you should not change the locale when displaying stuff to the user imho.

Android detect string/user input language

can I determine which language the user enter to editText ?
example :
if the user enter "поэзия song" witch contain from english and russian letter the methood return english, russian.
i dont care if the methood detect the language in the keybourd and return english, russian just becuase the user use in english and russian keybourds.
i prefere the second option becuase there is aproblam to determaine the language if it is UK becuase they use in the same letters
UPDATE:
there is away to tranlate variable (string) to user language and if editText contain english so no tranlate ?
like this :
string = "song" ;
englishletter = "abc..." ;
for(int i = 0 ; i < string.length(); i++ ){
if( string.contains(englishletter.substring(i,i+1)) {
num++;
}
}
if (num==0){
system.out.print(string.tranlsate());
} else {
system.out.print(string) ;
}

I don't think there's anything in Android that will do this for you. I would suggest integrating a library like this one: language-detection