How to Convert Java List or ArrayList into ResultSet

At this project i found an obstacle, which i need to convert a reporting module from fetching data from database into fetching data from Webservices. At first I think it was easy, I just fetch strings from Webservice, and put it in a bean or in a map and put it all in an ArrayList, just like JasperReport. But I forgot, this isn’t JasperReport I’m using, I’m using bloody hell CrystalReport. And my Crystal-Report-calling method only accepting ResultSet for parameter, so somehow I need to convert strings from webservice into ResultSet.

My idea is adding strings from webservices into an ArrayList<Object> and adding this ArrayList into ArrayList<ArrayList<Object>> and converting it into rows of ResultSet. And im using MockRunner library to help me. This is how I do it :

I create a class to convert a list into result set

package com.edw.rs;

import com.mockrunner.mock.jdbc.MockResultSet;
import java.sql.ResultSet;
import java.util.List;

/**
 *
 * @author edw
 */
public class MyResultSet {

    public ResultSet getResultSet(List<String> headers, List<List<Object>> data) throws Exception {

        // 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
        MockResultSet mockResultSet = new MockResultSet("myResultSet");

        // add header
        for (String string : headers) {          
            mockResultSet.addColumn(string);
        }

        // add data
        for (List<Object> list : data) {
            mockResultSet.addRow(list);
        }

        return mockResultSet;
    }
}

and i tested it with my junit class

package com.edw.rs.test;

import com.edw.rs.MyResultSet;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;
import org.apache.log4j.Logger;
import org.junit.Test;

/**
 *
 * @author edw
 */
public class MyResultSetTest {

    private Logger logger = Logger.getLogger(MyResultSetTest.class);

    public MyResultSetTest() {
    }

    @Test
    public void testMyResultSet() throws Exception {
        MyResultSet myResultSet = new MyResultSet();
        List<String> headers = new ArrayList<String>();
        headers.add("id");
        headers.add("name");
        headers.add("salary");
        headers.add("age");

        List<List<Object>> data = new ArrayList<List<Object>>();
        for (int i = 0; i < 4; i++) {
            List<Object> objects = new ArrayList<Object>();
            objects.add(new Integer(i));
            objects.add("name " + i);
            objects.add(new Double(i));
            objects.add(new Integer(20 + i));
            data.add(objects);
        }

        ResultSet rs = myResultSet.getResultSet(headers, data);
        while (rs.next()) {
            logger.debug(rs.getString("id"));
            logger.debug(rs.getString(2));
            logger.debug(rs.getDouble("salary"));
            logger.debug(rs.getInt(4));
            logger.debug("------------------------");
        }

    }
}

this is the result on my IDE console

2010-08-18 18:13:09,112 [MyResultSetTest] DEBUG com.edw.rs.test.MyResultSetTest:42 - 0
2010-08-18 18:13:09,131 [MyResultSetTest] DEBUG com.edw.rs.test.MyResultSetTest:43 - name 0
2010-08-18 18:13:09,132 [MyResultSetTest] DEBUG com.edw.rs.test.MyResultSetTest:44 - 0.0
2010-08-18 18:13:09,132 [MyResultSetTest] DEBUG com.edw.rs.test.MyResultSetTest:45 - 20
2010-08-18 18:13:09,133 [MyResultSetTest] DEBUG com.edw.rs.test.MyResultSetTest:46 - ------------------------
2010-08-18 18:13:09,133 [MyResultSetTest] DEBUG com.edw.rs.test.MyResultSetTest:42 - 1
2010-08-18 18:13:09,189 [MyResultSetTest] DEBUG com.edw.rs.test.MyResultSetTest:43 - name 1
2010-08-18 18:13:09,189 [MyResultSetTest] DEBUG com.edw.rs.test.MyResultSetTest:44 - 1.0
2010-08-18 18:13:09,189 [MyResultSetTest] DEBUG com.edw.rs.test.MyResultSetTest:45 - 21
2010-08-18 18:13:09,190 [MyResultSetTest] DEBUG com.edw.rs.test.MyResultSetTest:46 - ------------------------
2010-08-18 18:13:09,190 [MyResultSetTest] DEBUG com.edw.rs.test.MyResultSetTest:42 - 2
2010-08-18 18:13:09,191 [MyResultSetTest] DEBUG com.edw.rs.test.MyResultSetTest:43 - name 2
2010-08-18 18:13:09,218 [MyResultSetTest] DEBUG com.edw.rs.test.MyResultSetTest:44 - 2.0
2010-08-18 18:13:09,219 [MyResultSetTest] DEBUG com.edw.rs.test.MyResultSetTest:45 - 22
2010-08-18 18:13:09,219 [MyResultSetTest] DEBUG com.edw.rs.test.MyResultSetTest:46 - ------------------------
2010-08-18 18:13:09,219 [MyResultSetTest] DEBUG com.edw.rs.test.MyResultSetTest:42 - 3
2010-08-18 18:13:09,220 [MyResultSetTest] DEBUG com.edw.rs.test.MyResultSetTest:43 - name 3
2010-08-18 18:13:09,225 [MyResultSetTest] DEBUG com.edw.rs.test.MyResultSetTest:44 - 3.0
2010-08-18 18:13:09,226 [MyResultSetTest] DEBUG com.edw.rs.test.MyResultSetTest:45 - 23
2010-08-18 18:13:09,226 [MyResultSetTest] DEBUG com.edw.rs.test.MyResultSetTest:46 - ------------------------

this is my project structure, FYI im using Netbeans 6.9.
Netbeans 6.9 Project Structure

all i can say is, Thank You mockrunner, you saved my life.

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8 Comments

Serge

about 5 years ago

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

edwin

about 5 years ago

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"); }

AjAx

about 3 years ago

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

edwin

about 3 years ago

hi AjAx thank you for your information :D

Habib Ali Machpud

about 2 years ago

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

edwin

about 2 years ago

Yes, sorry bib, i was wrong :D

ccab

about 2 years ago

You can also use the pojoSample.jar api which implements resultset.. Much more thorough solution. http://scn.sap.com/docs/DOC-6147

Reply

edwin

about 2 years ago

Hi ccab, thank you for your information :)

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