Hi @winstonrenatan, thank you for trying my library and for getting in touch with me.

Please correct me in case I'm wrong but it seems that you are pretty new to programming in general. I get the impression that you should work through the basic Kotlin tutorials first. The variable detectedLanguage is not a string but an instance of Language which is an enum. Of course, you can put the text in its own variable first before feeding it into detectLanguageOf().

Apart from that, I don't understand your specific problem that you have with Android. What is a toast in this context? Can your provide a stacktrace of an error you get?

Hi @pemistahl, thank you for your warm welcome and help.

It is true that i am quite new in programming both in general and even kotlin basics. I actually just want simply to get the language of the text as a string, then output it in a toast where the user can see it. But I still don't understand how things actually works :(
Can you please guide me through, what should I do to obtain and print out the value of detectedLanguage, like what do I need to get the value of it in order to be printed out.
I have reached this point in my project, where I put the library in as a button.

languageButton.setOnClickListener{
       val detector: LanguageDetector = LanguageDetectorBuilder.fromLanguages(ENGLISH, FRENCH, GERMAN, SPANISH).build()
       val detectedLanguage: Language = detector.detectLanguageOf(text = "languages are awesome")
       Toast.makeText(this, detectedLanguage.toString(), Toast.LENGTH_SHORT).show()
}

But when I do click on the button that I created, the application terminate and show me this error

2020-04-17 22:04:44.702 5173-5173/com.github.winstonrenatan.skrispiv11 E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.github.winstonrenatan.skrispiv11, PID: 5173
    java.lang.ExceptionInInitializerError
        at com.github.pemistahl.lingua.api.LanguageDetectorBuilder.build(LanguageDetectorBuilder.kt:29)
        at com.github.winstonrenatan.skrispiv11.MainActivity$onCreate$2.onClick(MainActivity.kt:79)
        at android.view.View.performClick(View.java:6291)
        at android.view.View$PerformClick.run(View.java:24931)
        at android.os.Handler.handleCallback(Handler.java:808)
        at android.os.Handler.dispatchMessage(Handler.java:101)
        at android.os.Looper.loop(Looper.java:166)
        at android.app.ActivityThread.main(ActivityThread.java:7529)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:245)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:921)
     Caused by: java.util.regex.PatternSyntaxException: U_ILLEGAL_ARGUMENT_ERROR
    ^[\p{IsHiragana}\p{IsKatakana}\p{IsHan}]+$
        at java.util.regex.Pattern.compileImpl(Native Method)
        at java.util.regex.Pattern.compile(Pattern.java:1340)
        at java.util.regex.Pattern.<init>(Pattern.java:1324)
        at java.util.regex.Pattern.compile(Pattern.java:946)
        at kotlin.text.Regex.<init>(Regex.kt:89)
        at com.github.pemistahl.lingua.api.LanguageDetector.<clinit>(LanguageDetector.kt:381)
        	... 11 more

Thank you for your help I really do appreciate it so much, I'm sorry if I bothers and confused you through this questions and sorry for the late reply :(

Hello @winstonrenatan, I apologize myself now for this late response. My two-months-old little daughter is keeping me very busy at the moment.

Your stacktrace is very informative. There is a bug in the file LanguageDetector.kt in line 381. Character classes prefixed with Is- are not supported on Android.

Can you please clone this project's repository, replace the line with the following code, then build the library yourself and see whether your problem is gone? I'm not able to test on Android myself. If it works, I will provide a bug fix release in the near future. Thank you.

private val JAPANESE_CHARACTER_SET = try {
    Regex("^[\\p{Hiragana}\\p{Katakana}\\p{Han}]+$")
} catch (e: PatternSyntaxException) {
    Regex("^[\\p{IsHiragana}\\p{IsKatakana}\\p{IsHan}]+$")
}

I'm closing this issue now because commit 0078c01 most likely fixes this problem.