how to minimize the execution time for a java program?

Question

I have created a program in java for entering 1000 random numbers into two different database one for odd numbers and one for even. The code is executing fine but it takes nearly a minute to execute. How can I minimize the Execution time?

Here is the code:

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.text.DecimalFormat;
import java.text.NumberFormat;
import java.util.Random;

public class Test1 extends Thread {

public static void main(String[] args) throws ClassNotFoundException, SQLException {
    long start = System.currentTimeMillis();

    int evencount = 0;
    int oddcount = 0;
    int breakcon = 0;
    int breakcon1 = 0;

    Class.forName("com.mysql.jdbc.Driver");
    Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/db1" + "?useSSL=false", "root",
            "1234");
    Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/db2" + "?useSSL=false", "root",
            "1234");

    try {

        Class.forName("com.mysql.jdbc.Driver");

        for (int n = 1; n <= 1000; n++) {
            Random r = new Random();
            int val = r.nextInt(100000);

            if (val % 2 == 0) {
                PreparedStatement ps = con.prepareStatement(" insert into try values (?)");
                ps.setInt(1, val);
                ps.executeUpdate();
                ps.addBatch();
                breakcon = breakcon + 1;
                if (breakcon % 500 == 0 || breakcon == val)
                    ps.executeBatch();
                evencount++;

            } else {
                try {

                    Class.forName("com.mysql.jdbc.Driver");
                    PreparedStatement ps3 = conn.prepareStatement(" insert into try1 values (?)");
                    ps3.setInt(1, val);
                    ps3.executeUpdate();
                    ps3.addBatch();
                    breakcon1 = breakcon1 + 1;
                    if (breakcon1 % 500 == 0 || breakcon1 == val)
                        ps3.executeBatch();

                    oddcount++;

                }

                catch (Exception e2) {
                    System.out.println(e2);
                }
            }
        }

    }

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

    long end = System.currentTimeMillis();
    NumberFormat formatter = new DecimalFormat("#0.00000");
    System.out.println("Execution time is " + formatter.format((end - start) / 1000d) + " seconds");
    System.out.println(oddcount + evencount);

}
}

Answer 1

Instead of calling ps.executeUpdate(); (and ps3.executeUpdate();) after each time you setInt - do it only once after the for-loop. That's the whole point of using addBatch (aggregate inserts/updates and executing them all at once).

As Boris mentioned in the comment below, it would make the execution much faster if you also turn on rewriteBatchedStatements. See here how it can be achieved.