从多个结果集中将数据检索到单个Java列表中

Question

I have following three resultsets and a list. How can i iterate the three resultsets without using three while(rs1.next()) and return the data to the list.

public Optional<List<StudentDetails>> getStudDetails(String id)
    {
        List<StudentDetails> stud= new ArrayList<StudentDetails>();
        ResultSet rs1 = (ResultSet) storedProcedureCall.getObject(4);
        ResultSet rs2 = (ResultSet) storedProcedureCall.getObject(5);
        ResultSet rs3 = (ResultSet) storedProcedureCall.getObject(6);

    }

Answer 1

If the goal is to avoid writing the same code for all ResultSet s (3 loops) you could create a method that loops through a ResultSet , generates StudentDetails objects for each row and adds those to a list.

Here is an example:

public Optional<List<StudentDetails>> getStudDetails(String id){
    List<StudentDetails> stud= new ArrayList<StudentDetails>();
    ResultSet rs1 = (ResultSet) storedProcedureCall.getObject(4);
    ResultSet rs2 = (ResultSet) storedProcedureCall.getObject(5);
    ResultSet rs3 = (ResultSet) storedProcedureCall.getObject(6);
    addStudentDetails(stud, rs1);
    addStudentDetails(stud, rs2);
    addStudentDetails(stud, rs3);
}

private static void addStudentDetails(List<StudentDetails> list, ResultSet rs){
    while(rs.next()){
        list.add(new StudentDetails(rs.get.....));
    }
}

Answer 2

If the resultset contains only a single object, then you dont need to go for loops. Instead use simple if statements to check if the data is available.

Something like:

if(resultSet.hasNext()){
   Object obj= objresultSet.next();
}

do this for all of your ResultSet Objects