Re: JDBC compare the content of two tables

From:

Patricia Shanahan <pats@acm.org>

Newsgroups:

comp.lang.java.help

Date:

Wed, 08 Aug 2007 22:51:06 -0700

Message-ID:

<f9ea0e$2irc$1@ihnp4.ucsd.edu>

George3 wrote:

Thanks Patricia,

Is FieldComparator standard Java API? I can not find it from java.sun.com API
document. Could you provide more detailed information please? Especially how
to implement Map<String,FieldComparator>?

No, I'm suggesting defining a new interface. It could be something like:

interface FieldComparator{
   int compare(RowSet row1, int field1,
     RowSet row2, int field2);
}

A particular implementation might be something like:

FieldComparator doubleFieldComparator = new FieldComparator(){
   public int compare(RowSet row1, int field1,
     RowSet row2, int field2){
     double val1 = row1.getDouble(field1);
     double val2 = row2.getDouble(field2);
     return Double.compare(val1,val2);
   }
};

Map<String,FieldComparator> comparatorMap
   = new HashMap<String,FieldComparator>();

comparatorMap.put("DOUBLE",doubleFieldComparator);
....

To use this, given two result sets, a pair of possibly matching fields,
and a field type string:

FieldComparator comparator = comparatorMap.get(typeString);
int comparisonResult = comparator.compare(row1,field1,row2,field2);

Patricia