Convert between Java LocalDateTime and Instant

LocalDateTime to Instant

LocalDateTime localDateTime = LocalDateTime.now();

Instant instant = localDateTime.toInstant(ZoneOffset.UTC);

instant = localDateTime.atZone(ZoneId.systemDefault()).toInstant();	

long timeInSeconds = localDateTime.toEpochSecond(ZoneOffset.UTC);
instant = Instant.ofEpochSecond(timeInSeconds);

Instant to LocalDateTime

LocalDateTime localDateTime = LocalDateTime.ofInstant(Instant.now(), ZoneId.systemDefault());	

long timeInSeconds = 1567109422L;
localDateTime = LocalDateTime.ofInstant(Instant.ofEpochSecond(timeInSeconds), ZoneId.systemDefault());	

localDateTime = LocalDateTime.ofInstant(Instant.ofEpochSecond(timeInSeconds, 0), ZoneId.systemDefault());	

long timeInMillis = 1567109422123L;
localDateTime = LocalDateTime.ofInstant(Instant.ofEpochMilli(timeInMillis), ZoneId.systemDefault());	

localDateTime = Timestamp.from(Instant.now()).toLocalDateTime();