CODEWITHSUNDEEP
android-studiokotlinkotlin-android-extensions
nPn
nPn

Reputation: 16758

Unresolved reference: kotlinx

I am trying to try out Kotlin and the Kotlin Android extensions in Android Studio. I have tried this both in Android Studio v 1.5.1 on Ubuntu 14.04, and in Android Studio v 1.5.1 on OS X El Capitan with the same result.

Here is what I am doing:

  1. I install the Kotlin plugin 1.0.0-beta-35950-IJ141-11
  2. Create a new blank Android project
  3. Convert the MainActivity file to Kotlin (via help->findaction->convert file to kotlin)
  4. Configure the project for Kotlin

I then go into the generated content_main.xml file and add an id (hello) for the "Hello World!" TextView.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context="com.gmail.npnster.mykotlinfirstproject.MainActivity"
    tools:showIn="@layout/activity_main">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        android:id="@+id/hello"
        />
</RelativeLayout>

Then in the converted MainActivity I add a line to set the TextView. (shown below). Android Studio then prompts me (via alt-enter) to insert this line (also shown below)

import kotlinx.android.synthetic.main.content_main.*

So at this point everything seems fine

but then when I try to compile this I get 

Unresolved reference: kotlinx
Unresolved reference: kotlinx
Unresolved reference: hello

Notice that I did not install the Kotlin Android extensions plugin. As of a couple of days ago this is now supposed to be included in the main plug in and is marked as obsolete. (In fact if you try to install it when you have the latest plugin, nothing new is installed)

Anyone see what I am doing wrong?

MainActivity

import android.os.Bundle
import android.support.design.widget.FloatingActionButton
import android.support.design.widget.Snackbar
import android.support.v7.app.AppCompatActivity
import android.support.v7.widget.Toolbar
import android.view.View
import android.view.Menu
import android.view.MenuItem
import kotlinx.android.synthetic.main.content_main.*


class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        val toolbar = findViewById(R.id.toolbar) as Toolbar
        setSupportActionBar(toolbar)
        print("setting text view value to hey")
        hello.text = "hey"

        val fab = findViewById(R.id.fab) as FloatingActionButton
        fab.setOnClickListener { view -> Snackbar.make(view, "Replace this with your own action", Snackbar.LENGTH_LONG).setAction("Action", null).show() }
    }

    override fun onCreateOptionsMenu(menu: Menu): Boolean {
        // Inflate the menu; this adds items to the action bar if it is present.
        menuInflater.inflate(R.menu.menu_main, menu)
        return true
    }

    override fun onOptionsItemSelected(item: MenuItem): Boolean {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        val id = item.itemId

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true
        }

        return super.onOptionsItemSelected(item)
    }
}

Upvotes: 154

Views: 199330

Answers (21)

Muhammad Arslan
Muhammad Arslan

Reputation: 1

use this plug-in in your app project "Gradle script" folder in file "build.Gradle (Modules : progect_name)" : "Kotlin-android-extensions" then sync the projects.

Upvotes: 0

Samir
Samir

Reputation: 6617

Had same issue

plugins {
    id 'com.android.application'
    id 'kotlin-android'
    apply plugin: 'kotlin-android-extensions'
    apply plugin: "kotlin-kapt"
}

removed apply plugin: to idand restarted

plugins {
    id 'com.android.application'
    id 'kotlin-android'
    id 'kotlin-android-extensions'
    id "kotlin-kapt"
}

Upvotes: 2

Hasanboy Qodirov
Hasanboy Qodirov

Reputation: 21

In my case, adding:

apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'

at the end of the module-level build.grade fixed the issue.

Upvotes: 1

Awa Donalcien
Awa Donalcien

Reputation: 31

If you are in the year 2021 then i guess most of the solutions you see here wont be of any help to you so try this instead

  1. Go to your Module build.gradle file

  2. add id 'kotlin-android-extensions' to the plugins object {}

  3. Go to file the click on sync project with gradle files

Then go back and try to import kotlinx and that should work

Upvotes: 1

Sudarshan Sinha
Sudarshan Sinha

Reputation: 94

plugins {
    id 'com.android.application'
    id 'kotlin-android'
    id 'kotlin-android-extensions'
}

For me I just had to add id 'kotlin-android-extensions' to plugins in build.gradle(Module:AppName.app) And Sync it after that.

Upvotes: 0

Hakan Mutlu
Hakan Mutlu

Reputation: 11

in my case android studio line separator changed to CRLF( I am using macbook) windows settings. when switch to CR fix my error

Upvotes: 0

aga
aga

Reputation: 29454

Add kotlin-android-extensions in our buildscript's dependencies:

1. In your project-level build.gradle

buildscript {
    dependencies {
        classpath "org.jetbrains.kotlin:kotlin-android-extensions:$kotlin_version"
    }
}

and apply the kotlin-android-extensions plugin:

2. In your module-level build.gradle

apply plugin: 'kotlin-android-extensions'

Upvotes: 266

Hasan A Yousef
Hasan A Yousef

Reputation: 25008

With jetpack you have to use:

in the build.gradle (app)

    buildFeatures {
        dataBinding true
        viewBinding true
    }

   plugins {
      id 'kotlin-parcelize'
   }

In activity_main.xml

<androidx.constraintlayout.widget.ConstraintLayout
    tools:viewBindingIgnore="false">

In MainActivity.kt

import com.example.appname.databinding.ActivityMainBinding // ActivityMain is for main_activity.xml, and so on for any other activity

class MainActivity : AppCompatActivity() {

    private lateinit var binding: ActivityMainBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        val view = binding.root
        setContentView(view)

        binding.button.setOnClickListener {} // use binding.elementName
    }
}

Upvotes: 4

emkarachchi
emkarachchi

Reputation: 802

What worked for me in Android Studio 4.2 Beta 1 in macOS big sur to add id 'kotlin-android-extensions' to plugin section in app-level build.gradle file. So that it should look as follows.

plugins {
    id 'com.android.application'
    id 'kotlin-android'
    id 'kotlin-android-extensions'
}

Then sync the project and it should work

Upvotes: 6

Uriel Frankel
Uriel Frankel

Reputation: 14622

For me the only thing that helped was to click "File" -> "Invalidate caches / Restart..."

Upvotes: 0

Hyeonseo Yang
Hyeonseo Yang

Reputation: 1128

In my case, I had put the code referring the view in a companion object. How silly..

Upvotes: 0

Dawit Abraham
Dawit Abraham

Reputation: 1762

After applying the fixes mentioned above, I had to restart Android Studio to make it work.

Upvotes: 1

lbenedetto
lbenedetto

Reputation: 2114

The problem for me was the order in which I applied the plugins.

You must apply the kotlin-android plugin before the kotlin-android-extensions plugin

apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'

Upvotes: 6

Nopx
Nopx

Reputation: 549

Removing the following import fixed the issue for me.

import android.R

Upvotes: 8

AJ Snow
AJ Snow

Reputation: 93

I found out that I had support for C++ and Kotlin at the same time which was causing build problems.

When starting a new project, ensure C++ support is unchecked, and Kotlin support is checked. That fixed the problem for me.

Upvotes: 0

angryd
angryd

Reputation: 336

add apply plugin: 'kotlin-android-extensions' in app/buildgradle.

if you have already added it, try to remove it and sync gradle, when sync is complete, then add it back and Sync Gradle again. This work for me.

Upvotes: 6

Dobai Csaba Arpad
Dobai Csaba Arpad

Reputation: 1

This is how it worked for me. When I first configured Kotlin in Project, I selected the 1.1.2-3 version instead of 1.1.2-4 and added the following line in the build.gradle app file

apply plugin: 'kotlin-android-extensions'

after that I synced the build and it worked as expected.

Upvotes: 0

Liberty
Liberty

Reputation: 663

When you use Android Studio 2.0 and kotlin 1.0.1-2, you will come up with the same wrong. You cann't configure kotlin android extensions in your project's build.gradle, you need to configure and kotlin android extensions in every Module's build.gradle like this:

apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'

buildscript {
    ext.kotlin_version = '1.0.1-2'
    repositories {
        jcenter()
    }
    dependencies {
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
        classpath "org.jetbrains.kotlin:kotlin-android-extensions:$kotlin_version"
    }
}

android {
    compileSdkVersion 23
    buildToolsVersion "24.0.0 rc2"

    defaultConfig {
        applicationId "com.dazd.kotlindemo"
        minSdkVersion 14
        targetSdkVersion 23
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
    sourceSets {
       main.java.srcDirs += 'src/main/kotlin'
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:appcompat-v7:23.3.0'
    compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
}

Most importantly, even through the kotlin plugin included the kotlin android extension, you also need to configure the kotlin-android-extensions in your Module's bulid.gradle like this:

...
apply plugin: 'kotlin-android-extensions'
...
classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
classpath "org.jetbrains.kotlin:kotlin-android-extensions:$kotlin_version"

Of course, you could configure the kotlin plugin's classpath in your project's build.gradle.

Upvotes: 39

Maxime
Maxime

Reputation: 2078

I can't find it in the official documentation, but you must apply the plugin by adding the following to your build.gradle file:

apply plugin: 'kotlin-android-extensions'

Upvotes: 37

iajn
iajn

Reputation: 149

The buildscript block containing the kotlin-android-extensions dependency apparently needs to be in the app-module build.gradle, not in the top-level one.

Upvotes: 12

E-Kami
E-Kami

Reputation: 2669

I found why mine didn't work. My blocks were misplaced and by moving the buildscript{} block before the plugins as follow I got it working:

buildscript {
    ext.kotlin_version = '1.0.0-beta-3595'
    ext.anko_version = '0.8.1'

    repositories {
        jcenter()
    }
    dependencies {
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
        classpath "org.jetbrains.kotlin:kotlin-android-extensions:$kotlin_version"
    }
}

apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'

android {
    compileSdkVersion 23
    buildToolsVersion "23.0.2"

    defaultConfig {
        applicationId "com.kotlin"
        minSdkVersion 15
        targetSdkVersion 23
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
    sourceSets {
        main.java.srcDirs += 'src/main/kotlin'
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:appcompat-v7:23.1.1'
    compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
    compile "org.jetbrains.anko:anko-sdk15:$anko_version"
    compile "org.jetbrains.anko:anko-support-v4:$anko_version"
}

Upvotes: 8

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