Thing you want to do

--Description of the following 5 types of frequently used conversion methods

String
java.util.Date
java.sql.Date
LocalDate
LocalDateTime

String -> java.util.Date

    //conversion: SimpleDateFormat
    //exception: ParseException
    SimpleDateFormat format = new SimpleDateFormat("yyyy/MM/dd");
    date = format.parse("2019/04/01");

-> java.sql.Date

    //conversion:None
    //exception:None
    //The delimiter is "hyphen"(-)Only allowed "
　　java.sql.Date sqlDate= java.sql.Date.valueOf("2019-04-01");

-> LocalDate

    //conversion: DateTimeFormatter
    //exception:None(DateTimeParseException) 
    LocalDate.parse("2019/4/1", DateTimeFormatter.ofPattern("yyyy/MM/dd"));　//0 must be filled(Exception occurred)
    LocalDate.parse("2019/4/1", DateTimeFormatter.ofPattern("yyyy/M/d")) ;   //0 No need to fill

-> LocalDateTime

    //conversion: DateTimeFormatter
    //exception:None(DateTimeParseException)
    LocalDateTime.parse("2019/04/01", DateTimeFormatter.ofPattern("yyyy/MM/dd HH:mm:ss"));

java.util.Date -> String

    //conversion: SimpleDateFormat 
    //exception:None
    SimpleDateFormat format = new SimpleDateFormat("yyyy/MM/dd");
    format.format(new Date());

-> java.sql.Date

    //conversion:None
    //exception:None
    //point:Once milliseconds(Epoch time:The elapsed time from 1970 is used as an argument.)
    java.sql.Date sqlDate = new java.sql.Date(new java.util.Date().getTime());

-> LocalDate

    //conversion: Instant, ZoneDateTime
    //exception:None
    Date date = new Date();
    LocalDate localDate = date.toInstant().atZone(ZoneId.systemDefault()).toLocalDate();

-> LocalDateTime

    //conversion: Instant, ZoneDateTime
    //exception:None
    LocalDateTime localDateTime = date.toInstant().atZone(ZoneId.systemDefault()).toLocalDateTime();

java.sql.Date -> String

    //conversion- 
    //exception- 
    java.sql.Date date = java.sql.Date.valueOf("2019-04-01");
    String strDate = date.toString();

-> java.util.Date

★ I will write tomorrow.

-> LocalDate

★ I will write tomorrow.

-> LocalDateTime

★ I will write tomorrow.

LocalDate

-> String

    //conversion: DateTimeFormatter
    //exception:None
    LocalDate localDate = LocalDate.of(2019, 04, 01);
    String strDate = localDate.format(DateTimeFormatter.ofPattern("yyyy/MM/dd"));

-> java.util.Date

    //conversion: SimpleDateFormat
    //exception: ParseException
    //point: LocalDate -> String -> Date
　　localDate = LocalDate.of(2019, 04, 01);
    SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
    date = format.parse(localDate.toString());

-> java.sql.Date

    //conversion: -
    //exception: -
    LocalDate localDate = LocalDate.of(2019, 04, 01);
    java.sql.Date sqlDate = java.sql.Date.valueOf(localDate);

-> LocalDateTime

    //conversion: -
    //exception: -
    //point:Hours, minutes and seconds are 00:00:00
    LocalDate localDate = LocalDate.of(2019, 04, 01);    
    LocalDateTime localDateTime = localDate.atStartOfDay();

LocalDateTime

-> String

    //conversion: DateTimeFormatter
    //exception: -
    LocalDateTime localDate = LocalDateTime.of(2019, 04, 01, 23, 59, 58);
    String strDate = localDate.format(DateTimeFormatter.ofPattern("yyyy/MM/dd hh:mm:ss"));

-> java.util.Date

    //conversion: LocalDateTime -> ZonedDateTime -> Instant -> Date
    //exception-
    LocalDateTime localDateTime = LocalDateTime.of(2019, 04, 01, 23, 59, 58);
    Date date = Date.from(ZonedDateTime.of(localDateTime, ZoneId.systemDefault()).toInstant());

-> java.sql.Date

    //conversion: LocalDateTime -> LocalDate -> sql.Date
    //exception: -
    LocalDateTime localDateTime = LocalDateTime.of(2019, 04, 01, 23, 59, 58);
    java.sql.Date sqlDate = java.sql.Date.valueOf(localDateTime.toLocalDate());

-> LocalDate

    //conversion: -
    //exception: -
    LocalDateTime localDateTime = LocalDateTime.of(2019, 04, 01, 23, 59, 58);
    LocalDate localDate = localDateTime.toLocalDate();

Reference site

Sting -> java.sql.Date https://www.sejuku.net/blog/19077#StringSQLDate
String -> LocalDateTime https://qiita.com/riekure/items/d83d4ea5d8a19a267453
java.util.Date -> LocalDate https://qiita.com/hryshtk/items/43991beaabbb9d587360
LocalDate -> java.sql.Date https://code-examples.net/ja/q/15ddf55

[Java] Date type conversion

Thing you want to do

Reference site