import java.sql.*;
import java.util.*;

class Tmp extends Thread {

	private int newId() {
		Connection c = null;
		int result = 10000;
		try {
			c = DriverManager.getConnection(
					"jdbc:mysql://localhost/test",
					"root","password");
			Statement stmt = c.createStatement();
			stmt.executeUpdate("LOCK TABLES keynum WRITE");
			stmt.close();

			PreparedStatement pstmt = c.prepareStatement(
					"SELECT keyid FROM keynum");
			ResultSet rs = pstmt.executeQuery();
			rs.next();
			result = rs.getInt("keyid");
			result++;
			rs.close();

			PreparedStatement pstmt2 = c.prepareStatement(
					"UPDATE keynum SET keyid=?");
			pstmt2.setInt(1, result);
			pstmt2.executeUpdate();
			pstmt2.close();
		} catch(Exception e) {
			System.out.println(e.toString());
			System.exit(1);
		} finally {
			try {
				try {
					if (c != null) {
						Statement stmt = c.createStatement();
						stmt.executeUpdate("UNLOCK TABLES");
						stmt.close();
					}
				} catch(SQLException e) {
					System.out.println(e.toString());
				}
			} finally {
				close(c);
			}
		}
		return result;
	}

	private void close(Connection c) {
		if (c != null) {
			try {
				if (!c.isClosed()) {
					c.close();
				}
			} catch(SQLException e) {
				System.out.println(e.toString());
			}
		}
	}
	
	public void run() {
		while(true) {
			System.out.println("New id: "+newId());
		}
	}
}


public class mysql {

	static {
		try {
			Class.forName("com.mysql.jdbc.Driver");
		} catch(Exception e) {
			System.out.println(e);
			System.exit(1);
		}
	}
	
	public static void main(String[] args) throws Exception {
		List tmp = new ArrayList();
		for(int i = 0 ; i < 10 ; i++) {
			tmp.add(new Tmp());
		}
		Iterator i = tmp.iterator();
		while(i.hasNext()) {
			Thread t = (Thread)i.next();
			t.start();
		}
		i = tmp.iterator();
		while(i.hasNext()) {
			Thread t = (Thread)i.next();
			t.join();
		}
	}
}