Increasing Heap Space programatically

Question

Dear Experts,
Am using JDev 11.1.1.5.0. In my project am running a java class (testproduct.class) with main(), to generate excel file from Oracle Database.
Am passing a Query in my java code as shown below,
select * from testproduct where rownum<=100000;
But, it shows.
java.lang.OutOfMemoryError: Java heap space
How to increase the heap space through program. (i.e) How to increase my heapspace in (testproduct.class) code
-Thanks

Answer 1

Thanks Timo,
I use JDBC in my code. My code is,
public class Excel{
    public static void main(String[]args) throws Exception{
        try {
            Excel cexl = new Excel();
            cexl.Pass_Params(args[0], args[1], args[2],args[3], args[4]).get("Query");
        } catch (OutOfMemoryError e) {
            // TODO: Add catch code
            System.out.print("heap");
    public static HashMap Pass_Params(
            String url, String user, String password, String slno, String path) throws Exception{
        String val="Error";      
        try {
            Connection connection = null;
            Class.forName("oracle.jdbc.driver.OracleDriver");
            connection = DriverManager.getConnection(url, user, password);
            Statement s1 = connection.createStatement();
            ResultSet rs1 =
                s1.executeQuery("SELECT QRY FROM TEST1 WHERE SNO=" + slno);        
            String p = null;
            String filename = path;
            if (rs1.next()) {
                p = rs1.getString(1);
            ResultSet result = s1.executeQuery(p);
            HSSFWorkbook hwb = new HSSFWorkbook();
            HSSFSheet sheet = hwb.createSheet("new sheet");
            ResultSetMetaData rsmd = result.getMetaData();
            int cols = rsmd.getColumnCount();
            int vals = 0;
            HSSFRow rowhead = sheet.createRow(0);
            for (int i = 1; i <= cols; i++) {
                rowhead.createCell((int)i -
                                   1).setCellValue(rsmd.getColumnName(i));
            HSSFRow row;
            while (result.next()) {
                vals = vals + 1;
                row = sheet.createRow(vals);
                for (int i = 1; i <= cols; i++) {
                    row.createCell((int)i -
                                   1).setCellValue(result.getString(rsmd.getColumnName(i)));
            FileOutputStream fileOut = new FileOutputStream(filename);         
            hwb.write(fileOut);
            fileOut.close();
            System.out.println("done");
            System.out.println("Your excel file has been generated!");
            Process proc =
                Runtime.getRuntime().exec(" cmd /c start " + filename );
            HashMap map = new HashMap();
  val="done";         
            return map;
        } catch (Exception ex) {
            // TODO: Add catch code
            val=new String(ex.getMessage());
        finally {
                System.out.print(val);
        return null;