// Example 137 from page 109

//

import java.util.*;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.ResultSetMetaData;

import java.sql.SQLException;

import java.sql.Statement;

class Example137 {

public static void main(String[] args) throws SQLException {

String url = "jdbc:postgresql://localhost/messages";

String usr = "nobody";

String pwd = "";

System.out.println("To run this example you need a data base server, a");

System.out.println("database, and a suitable JDBC driver.");

try { Class.forName("postgresql.Driver"); }

catch (ClassNotFoundException e)

{ System.out.println("Cannot find the Postgresql driver"); }

Connection conn = DriverManager.getConnection(url, usr, pwd);

printNameAndMsg(getRows(conn, "select * from message"));

}

// Return the query result as an ArrayList of Map from String to Object

static ArrayList<Map<String,Object>> getRows(Connection conn, String query)

throws SQLException

{

Statement stmt = conn.createStatement();

ResultSet rset = stmt.executeQuery(query);

ResultSetMetaData rsmd = rset.getMetaData();

int columncount = rsmd.getColumnCount();

ArrayList<Map<String,Object>> queryResult

= new ArrayList<Map<String,Object>>();

while (rset.next()) {

Map<String,Object> row = new HashMap<String,Object>();

for (int i=1; i<=columncount; i++)

row.put(rsmd.getColumnName(i), rset.getObject(i));

queryResult.add(row);

}

return queryResult;

}

static void printNameAndMsg(Collection<Map<String,Object>> coll) {

for (Map<String,Object> row : coll)

System.out.println(row.get("name") + ": " + row.get("msg"));

}

}