これは何か

java.time.LocalTimeのtoString を読んだのでDateTimeFormatter を使う例を備忘録兼ねて書いておく。

どうってことないただのメモ書き。

コード

ログ出力にslf4jを使っているので実際に動かす際は依存関係に注意すること。

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.format.DateTimeFormatter;

public class App {

    private static final Logger logger = LoggerFactory.getLogger(App.class);
    private static final DateTimeFormatter formatter = DateTimeFormatter.ofPattern("HH:mm:ss.SSS");
    private static final DateTimeFormatter formatter2 = DateTimeFormatter.ofPattern("yyyy/MM/dd HH:mm:ss.SSS");

    public static void main(String... args) {

        var time = LocalTime.now();
        logger.info(time.toString());
        logger.info(time.format(formatter));

        time = LocalTime.of(14,30);
        logger.info(time.toString());
        logger.info(time.format(formatter));

        logger.info("---------------------");

        var datetime = LocalDateTime.now();
        logger.info(datetime.toString());
        logger.info(datetime.format(formatter2));

        datetime = LocalDateTime.of(2018,8,16,10,55);
        logger.info(datetime.toString());
        logger.info(datetime.format(formatter2));
    }
}

処理結果

16:08:49.562 [main] INFO  App - 16:08:49.555999800
16:08:49.572 [main] INFO  App - 16:08:49.555
16:08:49.572 [main] INFO  App - 14:30
16:08:49.572 [main] INFO  App - 14:30:00.000
16:08:49.572 [main] INFO  App - ---------------------
16:08:49.572 [main] INFO  App - 2018-08-16T16:08:49.572009800
16:08:49.573 [main] INFO  App - 2018/08/16 16:08:49.572
16:08:49.573 [main] INFO  App - 2018-08-16T10:55
16:08:49.573 [main] INFO  App - 2018/08/16 10:55:00.000