Example of SQL Batch

package reese.george;
 
/*
 
 Database Programming with JDBC and Java, Second Edition
 By George Reese
 ISBN: 1-56592-616-1
 
 Publisher: O'Reilly
 
 */
 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.Iterator;
 
/**
 * Example 4.1.
 */
public class Batch {
    static public void main(String[] args) {
	Connection conn = null;
 
	try {
	    ArrayList breakable = new ArrayList();
	    PreparedStatement stmt;
	    Iterator users;
	    ResultSet rs;
 
	    Class.forName(args[0]).newInstance();
	    conn = DriverManager.getConnection(args[1], args[2], args[3]);
	    stmt = conn.prepareStatement("SELECT user_id, password "
		    + "FROM user");
	    rs = stmt.executeQuery();
	    while (rs.next()) {
		String uid = rs.getString(1);
		String pw = rs.getString(2);
 
		// Assume PasswordCracker is some class that provides
		// a single static method called crack() that attempts
		// to run password cracking routines on the password
		// if( PasswordCracker.crack(uid, pw) ) {
		// breakable.add(uid);
		// }
	    }
	    stmt.close();
	    if (breakable.size() < 1) {
		return;
	    }
	    stmt = conn.prepareStatement("UPDATE user "
		    + "SET bad_password = 'Y' " + "WHERE uid = ?");
	    users = breakable.iterator();
	    while (users.hasNext()) {
		String uid = (String) users.next();
 
		stmt.setString(1, uid);
		stmt.addBatch();
	    }
	    stmt.executeBatch();
	} catch (Exception e) {
	    e.printStackTrace();
	} finally {
	    if (conn != null) {
		try {
		    conn.close();
		} catch (Exception e) {
		}
	    }
	}
    }
}