如何在时间戳中更改日期格式

Question

I'm using preparedStatement to update my sql table. Currently my date format is yyyy-mm-dd how to make it dd-mm-yyyy.

    try {
        Class.forName("com.mysql.jdbc.Driver");
        con = DriverManager.getConnection("jdbc:mysql://localhost:3306?user=root&password=1234&useSSL=false");
        con.setAutoCommit(false);
        pstmt = con.prepareStatement(qry);
        sp = con.setSavepoint();
        System.out.println("Enter your name");
        String name = sc.next();
        System.out.println("Enter your contact number");
        long phoneNum = sc.nextLong();
        System.out.println("Purpose of visit");
        String purpose = sc.next();

        pstmt.setString(1, name);
        pstmt.setLong(2, phoneNum);
        pstmt.setString(3, purpose);

         java.sql.Timestamp  dd = new java.sql.Timestamp(new java.util.Date().getTime());
        pstmt.setTimestamp(4, dd);
        pstmt.setTimestamp(5, dd);
        pstmt.executeUpdate();
        con.commit();

Answer 1

The terrible java.sql.Timestamp class is now legacy, no longer needed as of JDBC 4.2 and later. For database work, use OffsetDateTime instead, possibly adjusting to/from Instant or ZonedDateTime .

LocalDate

You seem to want only the date, without a time-of-day and without a time zone or offset-from-UTC.

To represent the date-only, use LocalDate class.

LocalDate ld = LocalDate.parse( "2019-01-23" ) ;  // By default, parses strings in standard ISO 8601 format: YYYY-MM-DD. 

To capture the current date, specific a time zone.

ZoneId z = ZoneId.systemDefault() ;
LocalDate ld = LocalDate.now( z ) ;

To generate text representing that value, use DateTimeFormatter .

DateTimeFormatter f = DateTimeFormatter.ofPattern( "dd-MM-uuuu" ) ;
String output = ld.format( f ) ;

JDBC

To write a LocalDate object to the database in a column of a data type akin to the standard-SQL type DATE :

myPreparedStatement.setObject( … , ld ) ;

Retrieve from database:

LocalDate ld = myResultSet( … , LocalDate.class ) ;

Answer 2

You can simply write below code to change the format as required.

java.sql.Timestamp dd = new java.sql.Timestamp(new java.util.Date().getTime());
String date = new java.text.SimpleDateFormat("dd-MM-yyyy").format(dd);
System.out.println(date);

Output : 27-06-2019