端末の24時間表示の設定チェック
DateFormat.is24HourFormat(context)を使用する
☓ Settings.System.getString(context.getContentResolver(),
Settings.System.TIME_12_24)
◯ DateFormat.is24HourFormat(context)
恐らく、24時設定を一度も設定していない端末でTIME_12_24の値を取得するとnullになる

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端末の24時間表示の設定チェック
DateFormat.is24HourFormat(context)を使用する
☓ Settings.System.getString(context.getContentResolver(),
Settings.System.TIME_12_24)
◯ DateFormat.is24HourFormat(context)
恐らく、24時設定を一度も設定していない端末でTIME_12_24の値を取得するとnullになる