How to Convert Java List or ArrayList into ResultSet

13 thoughts on “How to Convert Java List or ArrayList into ResultSet”

1. 

   Serge

   5 September 2011 at 20:00

   It’is very good expirience, but U have little mistake in MyResultSet row 20.
   This test work correctly only in this sample.

   Correction:
   for (List list : data) {
   if (list.size()==headers.size())
   {
   mockResultSet.addRow(list);
   }

   }

   Reply
   1. 

      edwin

      6 September 2011 at 12:51

      Hi Serge
      thank you for your comment, but could you elaborate more about class MyResultSet row 20? Because on row 20 is
      if (headers.size() != data.size()) {
throw new Exception("parameters size are not equals");
}
2. 

   AjAx

   24 March 2014 at 15:37

   Hi Edwin, this method is so great, I’ve used it in my Class, otherwise there is one problem on the execpetion throwing on MyResultSet row 20, the if condition should not be the header size equals the data size but the data.list’s size.

   Reply
   1. 

      edwin

      31 March 2014 at 20:13

      hi AjAx
      thank you for your information 😀
3. 

   Habib Ali Machpud

   18 February 2015 at 13:31

   Something strange in line 20, if (headers.size() != data.size())
   Do you want to compare header size with data size? I think the right comparison is between header size and data.list size.

   Reply
   1. 

      edwin

      3 March 2015 at 12:37

      Yes, sorry bib, i was wrong 😀
4. 

   ccab

   19 June 2015 at 02:49

   You can also use the pojoSample.jar api which implements resultset.. Much more thorough solution.

   http://scn.sap.com/docs/DOC-6147

   Reply
   1. 

      edwin

      7 July 2015 at 23:38

      Hi ccab, thank you for your information 🙂
5. 

   Anupam Das

   14 June 2018 at 13:50

   Hello Edwin,

   Greetings!

   Can you please share the code for “MockResultSet “.

   I am not able to add Column in the resultset and I want to refer your code for converting the arraylist to resultset.

   Reply
6. 

   pritesh

   3 April 2019 at 22:33

   very nice article. thanks a lot

   Reply
7. 

   pritesh

   3 April 2019 at 22:37

   thanks for the lovely article …really helped a lot.
   i just converted the above code in scala

   import java.sql.ResultSet
   import com.mockrunner.mock.jdbc.MockResultSet
   import scala.collection.mutable.ListBuffer

   class MyResultSet {

   @throws[Exception]
   def getResultSet(headers: List[String], data: ListBuffer[List[Object]]): ResultSet = { // validation

   if (headers == null || data == null)
   throw new Exception(“null parameters”)

   if (headers.size != data.size)
   throw new Exception(“parameters size are not equals”)

   // create a mock result set
   val mockResultSet = new MockResultSet(“myResultSet”)
   // add header
   for (clmn <- headers) {
   mockResultSet.addColumn(clmn)
   }
   // add data
   import scala.collection.JavaConversions._
   for (list <- data) {
   mockResultSet.addRow(list)
   }
   mockResultSet
   }
   }

   import scala.collection.mutable.ListBuffer

   object TestMockResultSet {

   def main(args: Array[String]): Unit = {

   val myResultSet: MyResultSet = new MyResultSet

   val headers = List("id","name","salary","age")
   var data = new ListBuffer[List[Object]]

   for (i <- 0 to 3) {
   val objects:List[Object] = List(new Integer(i),"name"+i,new Integer(i),new Integer(20+i))
   data += objects
   }

   val rs = myResultSet.getResultSet(headers, data)
   while(rs.next()){
   println(rs.getObject("id"))
   println(rs.getObject("name"))
   println(rs.getObject("age"))
   }
   }
   }

   Reply
8. 

   Ankita

   27 February 2021 at 11:07

   Hi Ed, I need help on below where I want to return all records from a table as resultset. but showing error

   here is my code
   public class Test {

   int i;
   String s;
   ResultSet resultSetSubject ;
   Statement stm;
   List lSubject ;

   Connection con;

   public Test()throws SQLException {

   con= DbUtil.getConnection();
   }

   public ResultSet getAllSubjects() throws SQLException{

   try {
   stm = con.createStatement();

   resultSetSubject = stm.executeQuery(“select * from subject”);
   while (resultSetSubject.next()) {

   resultSetSubject.getInt(1);
   resultSetSubject.getString(2);

   //System.out.println(resultSetSubject.getInt(“id”)+” “+resultSetSubject.getString(“name”));

   }
   } catch (Exception e) {
   System.out.println(e);
   }

   return resultSetSubject;

   }

   here is my Junit test code ResultSet rs = T.getAllSubjects();
   rs.next();
   assertEquals(rs.getInt(“id”),1);
   assertEquals(rs.getString(“name”),”Maths”);
   rs.next();

   Reply
9. 

   Ihar Bakhanovich

   7 November 2021 at 01:11

   Hi Edwin,
   thank you for the method.
   By me there is one problem: in the line 33 the classCastException is thrown. The iterator awaits the List, but ResultList is the List, that is why in the line 33 the iterator get Object[] and not the List.
   That is why i converted it after i get ResultList:
   private List<List> convertListOfArrayToListOfLists(List resultList) {
   List<List> result = new ArrayList();
   for (int i = 0; i < resultList.size(); i++) {
   List listOfObjects = new ArrayList();
   for (int j = 0; j < resultList.get(i).length; j++) {
   listOfObjects.add(resultList.get(i)[j]);
   }
   result.add(listOfObjects);
   }
   return result;
   }

   Reply