JDBC Transaction Test Case

import java.sql.Connection;
import java.sql.Driver;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class PostgresJDBCTest
{
	private static final String URL = "url";
	private static final String USERNAME = "username";
	private static final String PASSWORD = "password";

	private static final String CLASS_NAME = "org.postgresql.Driver";

	public static void main(String[] args)
	{
		try
		{
			Driver driver = (Driver)Class.forName(CLASS_NAME).newInstance();
			DriverManager.registerDriver(driver);
		}
		catch(Exception e)
		{
			System.err.println("Postgres Driver initialization failed: " + e.getMessage());
			System.exit(0);
		}

		Connection conn = null;

		try
		{
			conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);
			conn.setAutoCommit(false);
		}
		catch(Exception e)
		{
			System.err.println("Url, username,or password incorrect: " + e.getMessage());
			System.exit(0);
		}

		try
		{
			Statement st1 = conn.createStatement();
			st1.execute("create table example ( " +
					"	name varchar(255), " +
					"	primary key(name) " +
					")");
			st1.close();
			conn.commit();

			try
			{
				Statement query = conn.createStatement(ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY);
				query.executeQuery("select nam from example");
				query.close();
			}
			catch(Exception e)
			{
				e.printStackTrace();
			}

			Statement query2 = conn.createStatement(ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY);
			query2.executeQuery("select name from example");
			query2.close();
			conn.rollback();

			Statement st3 = conn.createStatement();
			st3.execute("drop table example");
			st3.close();
			conn.commit();

			System.out.println("Finished.");
		}
		catch(SQLException e)
		{
			e.printStackTrace();
		}

		if(conn != null)
		{
			try
			{
				conn.close();
			}
			catch(SQLException e)
			{
				try
				{
					conn.rollback();
					conn.close();
				}
				catch(Exception f)
				{
				}
			}
		}
	}
}