static final String JDBC_DRIVER = "org.postgresql.Driver";
static final String DB_URL = "jdbc:postgresql://localhost:5432/user1";

//  Database credentials
static final String USER = "root";
static final String PASS = "root";

public static void main(String[] args)
{
  Connection conn = null;
  Statement st = null;
 try{
    //STEP 2: Register JDBC driver
    Class.forName("org.postgresql.Driver");

    //STEP 3: Open a connection
    System.out.println("Connecting to database...");
    conn = DriverManager.getConnection("jdbc:postgresql://localhost:5432/","root","root");

    //STEP 4: Execute a query
    System.out.println("Creating statement...");
    st = conn.createStatement();
    String sql;
    sql = "SELECT  first, last FROM Employees";
    ResultSet rs = st.executeQuery(sql);

    //STEP 5: Extract data from result set
    while(rs.next()){
        //Retrieve by column name
        String first = rs.getString("first");
        String last = rs.getString("last");

        //Display values
        System.out.print(", First: " + first);
        System.out.println(", Last: " + last);
    }
    //STEP 6: Clean-up environment
    rs.close();
    st.close();
    conn.close();
}catch(SQLException se){
    //Handle errors for JDBC
    se.printStackTrace();
}catch(Exception e){
    //Handle errors for Class.forName
    e.printStackTrace();
}
finally
{
    //finally block used to close resources
    try{
        if(st!=null)
            st.close();
    }catch(SQLException se2){
    }// nothing we can do
    try{
        if(conn!=null)
            conn.close();
    }
    catch(SQLException se){
        se.printStackTrace();
    }//end finally try
}