[Android] DatePicker, TimePickerをDialogFragment で実装する

日付や時間をユーザーに入力してもらうために DatePicker や TimePicker を使うと便利です。
　

Android Studio 2021.2.1
API 30

DialogFragment

Pickerの実装についてはAndroid 3.0 以上で 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。
　

DatePicker

Google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るようですが
Stackoverflowによると
　
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
　
DatePick.java

//package your.package.name;

import android.app.DatePickerDialog;
import android.app.Dialog;
import android.os.Bundle;
import androidx.annotation.NonNull;
import androidx.fragment.app.DialogFragment;
import java.util.Calendar;

public class DatePick extends DialogFragment implements
        DatePickerDialog.OnDateSetListener{

    @Override
    @NonNull
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        final Calendar c = Calendar.getInstance();
        int year = c.get(Calendar.YEAR);
        int month = c.get(Calendar.MONTH);
        int day = c.get(Calendar.DAY_OF_MONTH);

        return new DatePickerDialog(getActivity(),
                (MainActivity)getActivity(),  year, month, day);
    }

    @Override
    public void onDateSet(android.widget.DatePicker view, int year,
                          int monthOfYear, int dayOfMonth) {
    }

}

//package your.package.name;

import android.app.DatePickerDialog;

import android.app.Dialog;

import android.os.Bundle;

import androidx.annotation.NonNull;

import androidx.fragment.app.DialogFragment;

import java.util.Calendar;

public class DatePick extends DialogFragment implements

DatePickerDialog.OnDateSetListener{

@Override

@NonNull

public Dialog onCreateDialog(Bundle savedInstanceState) {

final Calendar c = Calendar.getInstance();

int year = c.get(Calendar.YEAR);

int month = c.get(Calendar.MONTH);

int day = c.get(Calendar.DAY_OF_MONTH);

return new DatePickerDialog(getActivity(),

(MainActivity)getActivity(), year, month, day);

}

@Override

public void onDateSet(android.widget.DatePicker view, int year,

int monthOfYear, int dayOfMonth) {

}

　
元の設定：
return new DatePickerDialog(getActivity(), this, year, month, day);
新しい設定：
return new DatePickerDialog(getActivity(), (MainActivity)getActivity(), year, month, day);
DatePickerDialog() の第２引数が自分自信 this になっているので
これを、MainActivity にしてやります
　
MainActivity.java

//package com.example.testdatepicker;

import androidx.fragment.app.FragmentActivity;
import android.os.Bundle;
import android.app.DatePickerDialog.OnDateSetListener;
import androidx.fragment.app.DialogFragment;
import android.view.View;
import android.widget.DatePicker;
import android.widget.TextView;
import java.util.Locale;

public class MainActivity extends FragmentActivity implements OnDateSetListener {

    private TextView textView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        textView = findViewById(R.id.textView);
    }

    @Override
    public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) {

        String str = String.format(Locale.US, "%d/%d/%d",year, monthOfYear+1, dayOfMonth);
        textView.setText( str );

    }

    public void showDatePickerDialog(View v) {
        DialogFragment newFragment = new DatePick();
        newFragment.show(getSupportFragmentManager(), "datePicker");

    }
}

//package com.example.testdatepicker;

import androidx.fragment.app.FragmentActivity;

import android.os.Bundle;

import android.app.DatePickerDialog.OnDateSetListener;

import androidx.fragment.app.DialogFragment;

import android.view.View;

import android.widget.DatePicker;

import android.widget.TextView;

import java.util.Locale;

public class MainActivity extends FragmentActivity implements OnDateSetListener {

private TextView textView;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

textView = findViewById(R.id.textView);

}

@Override

public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) {

String str = String.format(Locale.US, "%d/%d/%d",year, monthOfYear+1, dayOfMonth);

textView.setText( str );

}

public void showDatePickerDialog(View v) {

DialogFragment newFragment = new DatePick();

newFragment.show(getSupportFragmentManager(), "datePicker");

}

　
DialogFragment にあった
onDateSet() 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"?>
<LinearLayout  xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:gravity="center"
    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_date"
        android:textSize="50sp"
        android:textColor="#000"
        android:layout_margin="30dp" />

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:onClick="showDatePickerDialog"
        android:layout_margin="30dp"
        android:text="@string/pick_date" />

</LinearLayout >

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

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

xmlns:tools="http://schemas.android.com/tools"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:orientation="vertical"

android:gravity="center"

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_date"

android:textSize="50sp"

android:textColor="#000"

android:layout_margin="30dp" />

<Button

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:onClick="showDatePickerDialog"

android:layout_margin="30dp"

android:text="@string/pick_date" />

</LinearLayout >

　
リソース
strings.xml

<resources>
    <string name="app_name">Your App Name</string>
    <string name="no_date">No Data</string>
    <string name="pick_date">Pick Date</string>
</resources>

</resources>

Time Picker

Time Pickerも同様に作成できます。
　
MainActivity.java

//package your.package.name;

import androidx.fragment.app.FragmentActivity;
import androidx.fragment.app.DialogFragment;
import android.os.Bundle;
import android.app.TimePickerDialog;
import android.view.View;
import android.widget.TextView;
import android.widget.TimePicker;
import java.util.Locale;


public class MainActivity extends FragmentActivity
        implements TimePickerDialog.OnTimeSetListener {

    private TextView textView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        textView = findViewById(R.id.textView);
    }

    @Override
    public void onTimeSet(TimePicker view, int hourOfDay, int minute) {

        String str = String.format(Locale.US, "%d:%d", hourOfDay, minute);
        textView.setText( str );

    }

    public void showTimePickerDialog(View v) {
        DialogFragment newFragment = new TimePick();
        newFragment.show(getSupportFragmentManager(), "timePicker");

    }
}

//package your.package.name;

import androidx.fragment.app.FragmentActivity;

import androidx.fragment.app.DialogFragment;

import android.os.Bundle;

import android.app.TimePickerDialog;

import android.view.View;

import android.widget.TextView;

import android.widget.TimePicker;

import java.util.Locale;

public class MainActivity extends FragmentActivity

implements TimePickerDialog.OnTimeSetListener {

private TextView textView;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

textView = findViewById(R.id.textView);

}

@Override

public void onTimeSet(TimePicker view, int hourOfDay, int minute) {

String str = String.format(Locale.US, "%d:%d", hourOfDay, minute);

textView.setText( str );

}

public void showTimePickerDialog(View v) {

DialogFragment newFragment = new TimePick();

newFragment.show(getSupportFragmentManager(), "timePicker");

}

　
TimePick.java

//package your.package.name;

import androidx.annotation.NonNull;
import androidx.fragment.app.DialogFragment;
import android.app.Dialog;
import android.app.TimePickerDialog;
import android.os.Bundle;
import android.widget.TimePicker;
import java.util.Calendar;

public class TimePick extends DialogFragment implements
        TimePickerDialog.OnTimeSetListener{

    @NonNull
    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        final Calendar c = Calendar.getInstance();
        int hour = c.get(Calendar.HOUR_OF_DAY);
        int minute = c.get(Calendar.MINUTE);

        return new TimePickerDialog(getActivity(),
                (MainActivity)getActivity(), hour, minute, true);
    }

    @Override
    public void onTimeSet(TimePicker view, int hourOfDay, int minute) {

    }
}

//package your.package.name;

import androidx.annotation.NonNull;

import androidx.fragment.app.DialogFragment;

import android.app.Dialog;

import android.app.TimePickerDialog;

import android.os.Bundle;

import android.widget.TimePicker;

import java.util.Calendar;

public class TimePick extends DialogFragment implements

TimePickerDialog.OnTimeSetListener{

@NonNull

@Override

public Dialog onCreateDialog(Bundle savedInstanceState) {

final Calendar c = Calendar.getInstance();

int hour = c.get(Calendar.HOUR_OF_DAY);

int minute = c.get(Calendar.MINUTE);

return new TimePickerDialog(getActivity(),

(MainActivity)getActivity(), hour, minute, true);

}

@Override

public void onTimeSet(TimePicker view, int hourOfDay, int minute) {

}

　
activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout  xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:gravity="center"
    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"
        android:layout_margin="30dp" />

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:onClick="showTimePickerDialog"
        android:layout_margin="30dp"
        android:text="@string/pick_time" />

</LinearLayout >

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

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

xmlns:tools="http://schemas.android.com/tools"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:orientation="vertical"

android:gravity="center"

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"

android:layout_margin="30dp" />

<Button

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:onClick="showTimePickerDialog"

android:layout_margin="30dp"

android:text="@string/pick_time" />

</LinearLayout >

　
strings.xml

<resources>
    <string name="app_name">Your App Name</string>
    <string name="no_data">"No Data"</string>
    <string name="pick_time">Pick Time</string>
</resources>

</resources>