class SimpleViewModelSolution : ViewModel() {
    private val _name = MutableLiveData("Ada")
    private val _lastName = MutableLiveData("Lovelace")
    private val _likes =  MutableLiveData(0)

    val name: LiveData<String> = _name
    val lastName: LiveData<String> = _lastName
    val likes: LiveData<Int> = _likes

    // popularity is exposed as LiveData using a Transformation instead of a @Bindable property.
    val popularity: LiveData<Popularity> = Transformations.map(_likes) {
        when {
            it > 9 -> Popularity.STAR
            it > 4 -> Popularity.POPULAR
            else -> Popularity.NORMAL
        }
    }

    fun onLike() {
        _likes.value = (_likes.value ?: 0) + 1
    }

    fun setName(name: String) {
        _name.value = name
    }

    fun setLastName(lastName: String) {
        _lastName.value = lastName
    }
}

enum class Popularity {
    NORMAL,
    POPULAR,
    STAR
}

@BindingAdapter("app:popularityIcon")
fun popularityIcon(view: ImageView, popularity: Popularity) {

    val color = getAssociatedColor(popularity, view.context)

    ImageViewCompat.setImageTintList(view, ColorStateList.valueOf(color))

    view.setImageDrawable(getDrawablePopularity(popularity, view.context))
}

private fun getAssociatedColor(popularity: Popularity, context: Context): Int {
    return when (popularity) {
        Popularity.NORMAL -> context.theme.obtainStyledAttributes(
            intArrayOf(android.R.attr.colorForeground)
        ).getColor(0, 0x000000)
        Popularity.POPULAR -> ContextCompat.getColor(context, R.color.popular)
        Popularity.STAR -> ContextCompat.getColor(context, R.color.star)
    }
}

private fun getDrawablePopularity(popularity: Popularity, context: Context): Drawable? {
    return when (popularity) {
        Popularity.NORMAL -> {
            ContextCompat.getDrawable(context, R.drawable.ic_person_black_96dp)
        }
        Popularity.POPULAR -> {
            ContextCompat.getDrawable(context, R.drawable.ic_whatshot_black_96dp)
        }
        Popularity.STAR -> {
            ContextCompat.getDrawable(context, R.drawable.ic_whatshot_black_96dp)
        }
    }
}

<layout
    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">

    <data>

        <variable
            name="viewmodel"
            type="com.example.android.databinding.basicsample.data.SimpleViewModelSolution"/>
    </data>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <!-- A simple binding between a TextView and a string observable in the ViewModel -->
        <TextView
            android:id="@+id/name"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_marginStart="16dp"
            android:layout_marginTop="8dp"
            android:layout_marginEnd="128dp"
            android:text="@{viewmodel.name}"
            android:textAppearance="@style/TextAppearance.AppCompat.Large"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/name_label"/>

        <!-- A simple binding between a TextView and a string observable in the ViewModel -->
        <TextView
            android:id="@+id/lastname"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_marginStart="16dp"
            android:layout_marginTop="8dp"
            android:layout_marginEnd="128dp"
            android:text="@{viewmodel.lastName}"
            android:textAppearance="@style/TextAppearance.AppCompat.Large"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/lastname_label"/>

        <!-- A custom Binding Adapter (`app:popularityIcon`) is used passing `viewmodel.popularity`
        as a parameter. Because it's a @Bindable property, the ImageView is automatically updated.
        -->
        <ImageView
            android:id="@+id/imageView"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="24dp"
            android:layout_marginEnd="24dp"
            android:contentDescription="@string/profile_avatar_cd"
            android:minWidth="48dp"
            android:minHeight="48dp"
            app:layout_constraintBottom_toTopOf="@+id/likes_label"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintVertical_bias="0.0"
            app:layout_constraintVertical_chainStyle="packed"
            app:popularityIcon="@{viewmodel.popularity}"/>

...

        <!-- Listeners can accept lambdas so in this case the ViewModel deals with the event,
        bypassing the activity. -->
        <Button
            android:id="@+id/like_button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="16dp"
            android:layout_marginEnd="8dp"
            android:onClick="@{() -> viewmodel.onLike()}"
            android:text="@string/like"
...

import androidx.fragment.app.activityViewModels
import androidx.fragment.app.viewModels

class HogeFragment : Fragment() {

    private val viewModel: SimpleViewModelSolution by activityViewModels()
　または、
    private val viewModel: SimpleViewModelSolution by viewModels()

dependencies {
    implementation "androidx.core:core-ktx:1.3.2"
    implementation "androidx.activity:activity-ktx:1.1.0"
    implementation "androidx.fragment:fragment-ktx:1.2.5"
}

kotlinOptions {
    jvmTarget = "1.8"
}

class HogeFragment : Fragment() {

    // Obtain ViewModel from ViewModelProviders
    private val viewModel by lazy {
        ViewModelProviders.of(this).get(SimpleViewModelSolution::class.java)
    }

    override fun onCreateView(
            inflater: LayoutInflater, container: ViewGroup?,
            savedInstanceState: Bundle?
    ): View? {
        // View Binding Use view binding in fragments
        _binding = FragmentFirstBinding.inflate(inflater, container, false)

        // use Fragment.viewLifecycleOwner for fragments
        binding.lifecycleOwner = viewLifecycleOwner
        binding.viewmodel = viewModel

        val view = binding.root
        return view
    }
}

class HogeFragment : Fragment() {

    private lateinit var viewModel: SimpleViewModelSolution

    override fun onCreateView(
            inflater: LayoutInflater, container: ViewGroup?,
            savedInstanceState: Bundle?
    ): View? {
        // View Binding Use view binding in fragments
        _binding = FragmentFirstBinding.inflate(inflater, container, false)

        // Create Vide Model
        viewModel = ViewModelProvider(this).get(SimpleViewModelSolution::class.java)
        // use Fragment.viewLifecycleOwner for fragments
        binding.lifecycleOwner = viewLifecycleOwner
        binding.viewmodel = viewModel

        val view = binding.root
        return view
    }
}

class NoticeDialogFragment : DialogFragment() {
    // Use this instance of the interface to deliver action events
    internal lateinit var listener: NoticeDialogListener

    /* The activity that creates an instance of this dialog fragment must
     * implement this interface in order to receive event callbacks.
     * Each method passes the DialogFragment in case the host needs to query it. */
    interface NoticeDialogListener {
        fun onDialogPositiveClick(dialog: DialogFragment)
        fun onDialogNegativeClick(dialog: DialogFragment)
    }

    // Override the Fragment.onAttach() method to instantiate the NoticeDialogListener
    override fun onAttach(context: Context) {
        super.onAttach(context)
        // Verify that the host activity implements the callback interface
        try {
            // Instantiate the NoticeDialogListener so we can send events to the host
            listener = context as NoticeDialogListener
        } catch (e: ClassCastException) {
            // The activity doesn't implement the interface, throw exception
            throw ClassCastException((context.toString() +
                    " must implement NoticeDialogListener"))
        }
    }

    override fun onCreateDialog(savedInstanceState: Bundle): Dialog {
        return activity?.let {
            // Build the dialog and set up the button click handlers
            val builder = AlertDialog.Builder(it)

            builder.setMessage(R.string.dialog_fire_missiles)
                    .setPositiveButton(R.string.fire,
                            DialogInterface.OnClickListener { dialog, id ->
                                // Send the positive button event back to the host activity
                                listener.onDialogPositiveClick(this)
                            })
                    .setNegativeButton(R.string.cancel,
                            DialogInterface.OnClickListener { dialog, id ->
                                // Send the negative button event back to the host activity
                                listener.onDialogNegativeClick(this)
                            })

            builder.create()
        } ?: throw IllegalStateException("Activity cannot be null")
    }
}

class MainActivity : FragmentActivity(),
        NoticeDialogFragment.NoticeDialogListener {

    fun showNoticeDialog() {
        // Create an instance of the dialog fragment and show it
        val dialog = NoticeDialogFragment()
        dialog.show(supportFragmentManager, "NoticeDialogFragment")
    }

    // The dialog fragment receives a reference to this Activity through the
    // Fragment.onAttach() callback, which it uses to call the following methods
    // defined by the NoticeDialogFragment.NoticeDialogListener interface
    override fun onDialogPositiveClick(dialog: DialogFragment) {
        // User touched the dialog's positive button
    }

    override fun onDialogNegativeClick(dialog: DialogFragment) {
        // User touched the dialog's negative button
    }
}

class NoticeDialogFragment : DialogFragment() {
    // Use this instance of the interface to deliver action events
    internal lateinit var listener: NoticeDialogListener

    /* The activity that creates an instance of this dialog fragment must
     * implement this interface in order to receive event callbacks.
     * Each method passes the DialogFragment in case the host needs to query it. */
    interface NoticeDialogListener {
        fun onDialogPositiveClick(dialog: DialogFragment)
        fun onDialogNegativeClick(dialog: DialogFragment)
    }

    // Override the Fragment.onAttach() method to instantiate the NoticeDialogListener
    override fun onAttach(context: Context) {
        super.onAttach(context)
        // Verify that the host activity implements the callback interface
        try {
            // Instantiate the NoticeDialogListener so we can send events to the host
            val fragment = getTargetFragment();
            listener = fragment as NoticeDialogListener
        } catch (e: ClassCastException) {
            // The activity doesn't implement the interface, throw exception
            throw ClassCastException((context.toString() +
                    " must implement NoticeDialogListener"))
        }
    }

    override fun onCreateDialog(savedInstanceState: Bundle): Dialog {
        return activity?.let {
            // Build the dialog and set up the button click handlers
            val builder = AlertDialog.Builder(it)

            builder.setMessage(R.string.dialog_fire_missiles)
                    .setPositiveButton(R.string.fire,
                            DialogInterface.OnClickListener { dialog, id ->
                                // Send the positive button event back to the host activity
                                listener.onDialogPositiveClick(this)
                            })
                    .setNegativeButton(R.string.cancel,
                            DialogInterface.OnClickListener { dialog, id ->
                                // Send the negative button event back to the host activity
                                listener.onDialogNegativeClick(this)
                            })

            builder.create()
        } ?: throw IllegalStateException("Activity cannot be null")
    }
}

class MainFragment : Fragment(),
        NoticeDialogFragment.NoticeDialogListener {

    fun showNoticeDialog() {
        // Create an instance of the dialog fragment and show it
        val dialog = NoticeDialogFragment()
        dialog.setTargetFragment(this, 12345)
        dialog.show(getFragmentManager(), "NoticeDialogFragment")
        // getChildFragmentManager() ?
    }

    // The dialog fragment receives a reference to this Activity through the
    // Fragment.onAttach() callback, which it uses to call the following methods
    // defined by the NoticeDialogFragment.NoticeDialogListener interface
    override fun onDialogPositiveClick(dialog: DialogFragment) {
        // User touched the dialog's positive button
    }

    override fun onDialogNegativeClick(dialog: DialogFragment) {
        // User touched the dialog's negative button
    }
}

class NoticeDialogFragment : DialogFragment() {
    // Use this instance of the interface to deliver action events
    internal lateinit var listener: NoticeDialogListener

    /* The activity that creates an instance of this dialog fragment must
     * implement this interface in order to receive event callbacks.
     * Each method passes the DialogFragment in case the host needs to query it. */
    interface NoticeDialogListener {
        fun onDialogPositiveClick(dialog: DialogFragment)
        fun onDialogNegativeClick(dialog: DialogFragment)
    }

    // Override the Fragment.onAttach() method to instantiate the NoticeDialogListener
    override fun onAttach(context: Context) {
        super.onAttach(context)
        // Verify that the host activity implements the callback interface
        try {
            // Instantiate the NoticeDialogListener so we can send events to the host
            val fragment = getParentFragment();
            listener = fragment as NoticeDialogListener
        } catch (e: ClassCastException) {
            // The activity doesn't implement the interface, throw exception
            throw ClassCastException((context.toString() +
                    " must implement NoticeDialogListener"))
        }
    }

    override fun onCreateDialog(savedInstanceState: Bundle): Dialog {
        return activity?.let {
            // Build the dialog and set up the button click handlers
            val builder = AlertDialog.Builder(it)

            builder.setMessage(R.string.dialog_fire_missiles)
                    .setPositiveButton(R.string.fire,
                            DialogInterface.OnClickListener { dialog, id ->
                                // Send the positive button event back to the host activity
                                listener.onDialogPositiveClick(this)
                            })
                    .setNegativeButton(R.string.cancel,
                            DialogInterface.OnClickListener { dialog, id ->
                                // Send the negative button event back to the host activity
                                listener.onDialogNegativeClick(this)
                            })

            builder.create()
        } ?: throw IllegalStateException("Activity cannot be null")
    }
}

class MainFragment : Fragment(),
        NoticeDialogFragment.NoticeDialogListener {

    fun showNoticeDialog() {
        // Create an instance of the dialog fragment and show it
        val dialog = NoticeDialogFragment()
        dialog.show(getChildFragmentManager(), "NoticeDialogFragment")
    }

    // The dialog fragment receives a reference to this Activity through the
    // Fragment.onAttach() callback, which it uses to call the following methods
    // defined by the NoticeDialogFragment.NoticeDialogListener interface
    override fun onDialogPositiveClick(dialog: DialogFragment) {
        // User touched the dialog's positive button
    }

    override fun onDialogNegativeClick(dialog: DialogFragment) {
        // User touched the dialog's negative button
    }
}

  override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
      return activity?.let {
          val builder = AlertDialog.Builder(it)
          // Get the layout inflater
          val inflater = requireActivity().layoutInflater;

          // Inflate and set the layout for the dialog
          // Pass null as the parent view because its going in the dialog layout
          let view = inflater.inflate(R.layout.dialog_signin, null)
          builder.setView(view)
                  // Add action buttons
                  .setPositiveButton(R.string.signin,
                          DialogInterface.OnClickListener { dialog, id ->
                              // sign in the user ...
                          })
                  .setNegativeButton(R.string.cancel,
                          DialogInterface.OnClickListener { dialog, id ->
                              getDialog().cancel()
                          })

          view.findViewById<>(R.id.hogehoge).xxxx

          builder.create()
      } ?: throw IllegalStateException("Activity cannot be null")
  }

  override fun onResume() {
    super.onResume()

    // 画面の大きさを取得する場合
    val displayWidth = resources.displayMetrics.widthPixels
    val displayHeight = resources.displayMetrics.heightPixels
    // 画面の大きさからダイアログの大きさを指定する場合
    val width = (displayWidth * 0.8f).toInt()
    val height = (displayHeight / 1.5f).toInt()

    // ダイアログの Window（android.view.Window）の大きさを直接指定する
    // val width = WindowManager.LayoutParams.MATCH_PARENT
    // val height = WindowManager.LayoutParams.MATCH_PARENT
    dialog?.window?.setLayout(width, height)
  }

FragmentA {
    val fragment = FragmentB.newInstance("hogehoge")

    val fragmentManager = supportFragmentManager
    val fragmentTransaction = fragmentManager.beginTransaction()
    fragmentTransaction.add(R.id.fragment_container, fragment)
    fragmentTransaction.commit()
}

class FragmentB : Fragment() {

...

    companion object {
       private val BUNDLE_STR = "BUNDLE_STR"
       private val BUNDLE_INT = "BUNDLE_INT"

       fun onCreate( ... ) {
           val strValue = arguments.getString(BUNDLE_STR, "default")
           val intValue = arguments.getInt(BUNDLE_INT)
           ...
       }

       fun newInstance(strValue: string, ... ): FragmentB {
            return FragmentB().apply {
                arguments = Bundle().apply {
                    putString(BUNDLE_STR, strValue)
                    putInt(BUNDLE_INT, intValue)
                }
            }
        }
    }
}

        <!-- "@font/ipaexg"で IPAexゴシック -->
        <TextView
            android:id="@+id/text_view"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:fontFamily="@font/ipaexg" />

        <!-- "@font/ipaexm"で IPAex明朝 -->
        <TextView
            android:id="@+id/text_view"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:fontFamily="@font/ipaexm" />

<?xml version="1.0" encoding="utf-8"?>
<font-family xmlns:android="http://schemas.android.com/apk/res/android">

    <!-- normal = IPAex明朝 -->
    <font
        android:fontStyle="normal"
        android:fontWeight="400"
        android:font="@font/ipaexm" />

    <!-- italic = IPAexゴシック -->
    <font
        android:fontStyle="italic"
        android:fontWeight="400"
        android:font="@font/ipaexg" />
</font-family>

...

        <!-- italic = IPAexゴシックで bold 「太字」 -->
        <TextView
            android:id="@+id/text_view"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:fontFamily="@font/ipaex"
            android:textStyle="bold|italic" />

        <!-- normal = IPAex明朝 -->
        <TextView
            android:id="@+id/text_view"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:fontFamily="@font/ipaex"
            android:textStyle="normal" />

# custom Android Studio VM options, see https://developer.android.com/studio/intro/studio-config.html
-Dfile.encoding=UTF-8
-Xmx1280m
-XX:ReservedCodeCacheSize=240m

DataBinderMapperImpl.java:9: �G���[: �V���{�������‚����܂���
import com.example.test_my_application.databinding.FragmentFirstBindingImpl;
                                                  ^
  �V���{��:   �N���X FragmentFirstBindingImpl
  �ꏊ: �p�b�P�[�W com.example.test_my_application.databinding

Menu ＞ Help ＞ Edit Custom VM Options...

-Dfile.encoding=UTF-8

DataBinderMapperImpl.java:9: エラー: シンボルを見つけられません
import com.example.test_my_application.databinding.FragmentFirstBindingImpl;
                                                  ^
  シンボル:   クラス FragmentFirstBindingImpl
  場所: パッケージ com.example.test_my_application.databinding

Android\app\build\intermediates\incremental\mergeDebugResources\merged.dir\values\values.xml:630: warn: multiple substitutions specified in non-positional format; did you mean to add the formatted="false" attribute?.

<string name="test_string_format">Value is %s, %d</string>
　を、下記の様に書き直す
<string name="test_string_format" formatted="false">Value is %s, %d</string>
<string name="test_string_format">Value is $s, $d</string>
<string name="test_string_format">Value is %1$s, %2$d</string>

> Task :app:kaptDebugKotlin
警告: Binding adapter AK(android.view.View, float) already exists for android:paddingStart !
Overriding androidx.databinding.adapters.ViewBindingAdapter#setPaddingStart

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.test_my_application/com.example.test_my_application.MainActivity}: java.lang.IllegalStateException: Required DataBindingComponent is null in class FragmentFirstBindingImpl. A BindingAdapter in com.example.test_my_application.BindingAdapters is not static and requires an object to use, retrieved from the DataBindingComponent. If you don't use an inflation method taking a DataBindingComponent, use DataBindingUtil.setDefaultComponent or make all BindingAdapter methods static.

Caused by: java.lang.IllegalStateException: Required DataBindingComponent is null in class FragmentFirstBindingImpl. A BindingAdapter in com.example.test_my_application.BindingAdapters is not static and requires an object to use, retrieved from the DataBindingComponent. If you don't use an inflation method taking a DataBindingComponent, use DataBindingUtil.setDefaultComponent or make all BindingAdapter methods static.

@JvmStatic

https://github.com/android/databinding-samples/blob/master/TwoWaySample/app/src/main/java/com/example/android/databinding/twowaysample/ui/BindingAdapters.kt

 * Also, keep in mind that @JvmStatic is only necessary if you define the methods inside a class or
 * object. Consider moving the Binding Adapters to the top level of the file.

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.test_my_application/com.example.test_my_application.MainActivity}: android.view.InflateException: Binary XML file line #138: Binary XML file line #138: You must supply a layout_width attribute.

android:layout_width="@{test_width_float, default=wrap_content}"

<TextView id='@+id/text_view_x'> conflicts with another tag that has the same ID

Invalidate Caches/Restart

 textAllCaps:textAllCaps="false"

 <>"  false     S    P   A   C   EEEEE  "</>
 <>&#32;ABC&#32;</>

 TextView.setText Html.fromHtml("<h>HOGEHOGE</h>");

Incompatible Kotlin/Native libraries
  There is a library libraries from the Kotlin/Native 1.3.61 distribution attached to the project: stdlib
  These libraries were compiled with an older Kotlin/Native compiler and can't be read in IDE.
  Please edit Gradle buildfile(s) to use Kotlin Gradle plugin version 1.4.20. Then re-import the project in IDE.

Incompatible Kotlin/Native libraries
  There are 32 third-party libraries attached to the project that were compiled with an older Kotlin/Native compiler and cant be read in IDE:
  Gradle: com.soywiz.korlibs.klock:klock-iosarm64:klib:1.8.6
  Gradle: com.soywiz.korlibs.klock:klock-iosx64:klib:1.8.6

Please edit Gradle buildfile(s) and specify library a version compatible with Kotlin/Native 1.4.20. Then re-import the project in IDE.

23:00  Android Studio is using the following JDK location when running Gradle:
      C:\Android\android-studio\jre
      Using different JDK locations on different processes might cause Gradle to
      spawn multiple daemons, for example, by executing Gradle tasks from a terminal
      while using Android Studio.

      More info...
      Select a JDK from the File System
      Do not show this warning again

rem ビルド キャッシュのクリアと gradle daemonの停止（リセット）
rem ビルド キャッシュの削除
gradlew clean cleanBuildCache
gradlew --stop

Androidのアプリ開発で AAR形式のライブラリを Androidプロジェクトに組み込む方法

Android JNI NDKの C言語側で R.rawや Assetのファイルを FileDescriptor経由で直接読み込む方法

Kotlin大嫌い人間が Kotlin言語を必死に勉強する

2019年になったから Android Architecture Componentsで開発しようじゃないか！今から始めても遅くない！

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