[Android & Kotlin] TimePicker の実装

Androidでは日付や時間をユーザー入力のために TimePicker や DatePickerを使うとユーザビリティが上がります。Kotlinではどのように設定するのでしょうか確認してみます。
　

Android Studio
2021.1.1

DialogFragment

Pickerの実装については DialogFragment を使うことが推奨されています。また、Time Picker はDate Picker と同様に作成できます。

尚、DatePickerのケースは以下を参考に
　

as42021.1.1 picker 00b 100x100 - [Android & Kotlin] TimePicker の実装

[Android & Kotlin] DatePickerの実装

Androidでは日付や時間をユーザー入力のために DatePicker や TimePicker などを使うとユーザビリティが上がります。...

目次
1. TimePicker
2. サンプルコード

TimePicker

　Picker

の解説では、Layout の android:onClick で Activity のメソッドが呼ばれ、Picker の DialogFragment が表示されます。

<Button
    ...
    android:onClick="showTimePickerDialog" />

<Button

...

android:onClick="showTimePickerDialog" />

　
では、設定したデータをどうやって取り出すのか？
　
Layout での android:onClick をやめてしまうという方法もありますが
Picker の DatePickerDialog.OnDateSetListener を使って、 MainActivity にデータを戻してやればいいようです

サンプルコード

新たに、Kotlin　のクラスファイルを作成します。
TimePick.kt

//package com.example.testtimepicker

import android.app.Dialog
import android.widget.TimePicker
import android.app.TimePickerDialog
import android.icu.util.Calendar
import android.os.Bundle
import androidx.fragment.app.DialogFragment

class TimePick : DialogFragment(), TimePickerDialog.OnTimeSetListener {

    // Bundle sould be nullable, Bundle?
    override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
        // to initialize a Calender instance
        val c = Calendar.getInstance()

        // at the first, to get the system current hour and minute
        val hour = c.get(Calendar.HOUR_OF_DAY)
        val minute = c.get(Calendar.MINUTE)

        return TimePickerDialog(
            activity,
            // in order to return parameters to MainActivity
            activity as MainActivity?,
            hour,
            minute,
            true)
    }

    override fun onTimeSet(view: TimePicker, hourOfDay: Int, minute: Int) {
        //
    }
}

//package com.example.testtimepicker

import android.app.Dialog

import android.widget.TimePicker

import android.app.TimePickerDialog

import android.icu.util.Calendar

import android.os.Bundle

import androidx.fragment.app.DialogFragment

class TimePick : DialogFragment(), TimePickerDialog.OnTimeSetListener {

// Bundle sould be nullable, Bundle?

override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {

// to initialize a Calender instance

val c = Calendar.getInstance()

// at the first, to get the system current hour and minute

val hour = c.get(Calendar.HOUR_OF_DAY)

val minute = c.get(Calendar.MINUTE)

return TimePickerDialog(

activity,

// in order to return parameters to MainActivity

activity as MainActivity?,

hour,

minute,

true)

}

override fun onTimeSet(view: TimePicker, hourOfDay: Int, minute: Int) {

}

　
元の設定：
return new DatePickerDialog(activity, this, year, month, day);
新しい設定：
return new DatePickerDialog(this.context as Context, activity asMainActivity?, …);
DatePickerDialog() の第２引数が自分自身 this になっているので
これを、MainActivity? にしてやります
　
MainActivity.kt

//package com.example.testtimepicker

import android.app.TimePickerDialog
import android.os.Bundle
import android.view.View
import android.widget.TimePicker
import androidx.fragment.app.FragmentActivity
// ViewBinding
import com.example.testtimepicker.databinding.ActivityMainBinding


class MainActivity : FragmentActivity(), TimePickerDialog.OnTimeSetListener {

    private lateinit var binding: ActivityMainBinding

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

    }

    override fun onTimeSet(view: TimePicker, hourOfDay: Int, minute: Int) {

        val str: String = getString(R.string.stringformat, hourOfDay, minute)
        binding.textView.text = str

    }

    // called by Buttton tapping
    fun showTimePickerDialog(v: View) {
        val newFragment = TimePick()
        newFragment.show(supportFragmentManager, "timePicker")

    }
}

//package com.example.testtimepicker

import android.app.TimePickerDialog

import android.os.Bundle

import android.view.View

import android.widget.TimePicker

import androidx.fragment.app.FragmentActivity

// ViewBinding

import com.example.testtimepicker.databinding.ActivityMainBinding

class MainActivity : FragmentActivity(), TimePickerDialog.OnTimeSetListener {

private lateinit var binding: ActivityMainBinding

override fun onCreate(savedInstanceState: Bundle?) {

super.onCreate(savedInstanceState)

binding = ActivityMainBinding.inflate(layoutInflater)

setContentView(binding.root)

}

override fun onTimeSet(view: TimePicker, hourOfDay: Int, minute: Int) {

val str: String = getString(R.string.stringformat, hourOfDay, minute)

binding.textView.text = str

}

// called by Buttton tapping

fun showTimePickerDialog(v: View) {

val newFragment = TimePick()

newFragment.show(supportFragmentManager, "timePicker")

}

　
DialogFragment にあった
onTimeSet() を持ってきてデータを受け取ります
　
レイアウトです
activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 
    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"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/textView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:text="@string/no_data"
        android:textSize="50sp"
        android:textColor="#000"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.4"/>

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:onClick="showTimePickerDialog"
        android:layout_margin="30dp"
        android:text="@string/pick_time"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.6"/>
    

</androidx.constraintlayout.widget.ConstraintLayout>

<?xml version="1.0" encoding="utf-8"?>

<androidx.constraintlayout.widget.ConstraintLayout

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"

tools:context=".MainActivity">

<TextView

android:id="@+id/textView"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:gravity="center"

android:text="@string/no_data"

android:textSize="50sp"

android:textColor="#000"

app:layout_constraintBottom_toBottomOf="parent"

app:layout_constraintLeft_toLeftOf="parent"

app:layout_constraintRight_toRightOf="parent"

app:layout_constraintTop_toTopOf="parent"

app:layout_constraintVertical_bias="0.4"/>

<Button

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:onClick="showTimePickerDialog"

android:layout_margin="30dp"

android:text="@string/pick_time"

app:layout_constraintBottom_toBottomOf="parent"

app:layout_constraintLeft_toLeftOf="parent"

app:layout_constraintRight_toRightOf="parent"

app:layout_constraintTop_toTopOf="parent"

app:layout_constraintVertical_bias="0.6"/>

</androidx.constraintlayout.widget.ConstraintLayout>

　
リソース
strings.xml

<resources>
    <string name="app_name">TestTimePicker</string>
    <string name="no_data">"No Data"</string>
    <string name="pick_time">Pick Time</string>
    <string name="stringformat">%02d:%02d</string>
</resources>

<string name="app_name">TestTimePicker</string>

</resources>

　
build.gradle

...
android {
    ...
    buildFeatures {
        viewBinding true
    }
}
...

...

android {

...

buildFeatures {

viewBinding true

}

...

Reference:
Picker API Developer’s Guide | Picker | Google Developers