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:
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)
}
}
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'
Original answer:
Most likely it's a bug in the Kotlin plugin. I've filed an issue on their tracker.