Use LocalDateTime#parse() (or ZonedDateTime#parse() if the string happens to contain a time zone part) to parse a String in a certain pattern into a LocalDateTime.

String oldstring = "2011-01-18 00:00:00.0";
LocalDateTime datetime = LocalDateTime.parse(oldstring, DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.S"));

Then use LocalDateTime#format() (or ZonedDateTime#format()) to format a LocalDateTime into a String in a certain pattern.

String newstring = datetime.format(DateTimeFormatter.ofPattern("yyyy-MM-dd"));
System.out.println(newstring); // 2011-01-18

Or, when you're not on Java 8 yet, use SimpleDateFormat#parse() to parse a String in a certain pattern into a Date.

String oldstring = "2011-01-18 00:00:00.0";
Date date = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.S").parse(oldstring);

Then use SimpleDateFormat#format() to format a Date into a String in a certain pattern.

String newstring = new SimpleDateFormat("yyyy-MM-dd").format(date);
System.out.println(newstring); // 2011-01-18

See also:

• Java string to date conversion

Update: as per your failed attempt which you added to the question after this answer was posted; the patterns are case sensitive. Carefully read the java.text.SimpleDateFormat javadoc what the individual parts stands for. So stands for example M for months and m for minutes. Also, years exist of four digits yyyy, not five yyyyy. Look closer at the code snippets I posted here above.

Thanks to @Andy Brown. In addition to what Andy Brown has answered, I'm posting the complete snippet

Complete Solution:

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class SampleDate {
    public static void main(String[] args) throws ParseException {
        DateFormat parseFormat = new SimpleDateFormat(
                 "yyyy-MM-dd'T'HH:mm:ss.SSSZ");
        Date date = parseFormat.parse("2012-03-16T00:00:00.000-0500");
        String strDate = parseFormat.format(date);
        System.out.println(strDate);

        // if you get date of type 'java.sql.Date' directly from database cursor like
         //rs.getDate("created_date"), just pass it directly to format()

        SimpleDateFormat dateFormat = new SimpleDateFormat(
                "dd-MMM-yyyy HH:mm:ss");
        String stringDate = dateFormat.format(date);
        System.out.println(stringDate);

    }
}

/*
Output:

2012-03-16T01:00:00.000-0400
16-Mar-2012 01:00:00

*/

you can also convert java.util.Date to java.sql.Date like this,

String dateString = "03-11-2012";
    SimpleDateFormat dateFormat = new SimpleDateFormat("MM-dd-yyyy");
    java.util.Date date = dateFormat.parse(dateString);
    java.sql.Date sqlDate = new Date(date.getTime());
// set the input param type as OracleTypes.DATE and pass the input param date as sqlDate

Approach 1: Using java.time.LocalDateTime. (Strongly Preferred)

DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy/MM/dd HH:mm:ss");
LocalDateTime now = LocalDateTime.now();
System.out.println(dtf.format(now)); //2016/11/16 12:08:43

Approach 2: Using java.util.Date.

DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
Date date = new Date();
System.out.println(dateFormat.format(date)); //2016/11/16 12:08:43

Approach 3: Using java.util.Calendar.

DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
Calendar cal = Calendar.getInstance();
System.out.println(dateFormat.format(cal)); //2016/11/16 12:08:43