Is there a way to copy Date object into another date Object without using a reference?

Question

I got a program that loads in raw data for charting and stores it in a class called cRawGraph.. It then formats this data and stores it in another class called cFormatGraph. Is there a way to copy some of the date objects stored in cRwGraph to date objects stored in cFormattedGraph without using a reference? I looked at Oracle's documentation and did not see a constructor that would take in a date object or any methods data would accomplish this.

code snippet:

do{
        d=rawData.mDate[i].getDay();
        da=rawData.mDate[i];
        datept=i;
        do{
          vol+=rawData.mVol[i];
          pt+=rawData.mPt[i];
          c++;
          i++;
          if (i>=rawData.getSize())
              break;
          } while(d==rawData.mDate[i].getDay());

        // this IS NOT WORKING BECOUSE IT IS A REFRENCE AND RawData gets loaded with new dates,
        // Thus chnaging the value in mDate
        mDate[ii]=da;

      mVol[ii]=vol;
      mPt[ii]=pt/c;
      if (first)
      {
          smallest=biggest=pt/c;
          first=false;
      }
      else
      {
          double temp=pt/c;
          if (temp<smallest)
              smallest=temp;
          if (temp>biggest)
              biggest=temp;

      }
      ii++;
    } while(i<rawData.getSize());  

Answer 1

You could use getTime() and passing it into the Date(time) constructor. This is only required because Date is mutable.

Date original = new Date();
Date copy = new Date(original.getTime());

If you're using Java 8 try using the new java.time API which uses immutable objects. So no need to copy/clone.

Answer 2

With Java 8 you can use the following nullsafe code.

Optional.ofNullable(oldDate)
               .map(Date::getTime)
               .map(Date::new)
               .orElse(null)

Answer 3

If possible, try switching to using Joda Time instead of the built in Date type.

http://www.joda.org/joda-time/

DateTime from Joda has a copy constructor, and is generally nicer to work with since DateTime is not mutable.

Otherwise you could try:

Date newDate = new Date(oldDate.getTime());