Using JDBC with Java Applications and Applets 90 (Ez web hosting)
Using JDBC with Java Applications and Applets 90 the acc_id numbers from the ResultSet as a String object. The String is added to the vector. The loop pulls each of the account numbers and places them in the vector. Notice that the catch doesn t do anything with a potential error. This will be fixed in our next iteration of the code. Once the vector has been populated, the JList component is created using the vector. After the JList is created, the code puts a scroll pane around it so that the user will be able to have scrollbars available to see all of the account numbers in the list. The Get Account Button After the JList component, the buildGUI() method creates the GUI s only button, called Get Account. The user will click this button after clicking on an appropriate account number. The code begins by instantiating the button and labeling it, and then moves to the action associated with it. In our code example, we build the event processing code right into the button itself instead of having the application implement the ActionListener interface. When the user clicks on the Get Account button, its ActionListener() will fire. We want the code to pick up the account number currently selected on the JList control and use the value to pull all of the account information from the MySQL database and place that information in the five JTextField controls. To accomplish this, a try/catch block is coded with the database control within it. A Statement object is instantiated from the Connection object, and the execute- Query() method is called. The parameter to the executeQuery() method is the SQL string that we want executed against the MySQL database. The full string is ResultSet rs = statement.executeQuery( “SELECT * FROM acc_acc WHERE acc_id = ” + accountNumberList.getSelectedValue()); As you can see from the string, we have a SELECT statement that will pull all columns from the database where the acc_id is equal to the current selected value on the JList control. If the query isn t successful, the catch block is called, but there is no error-handling at the moment. If the SQL was successful and there is a result in the ResultSet object, each of the JTextField controls are populated by pulling the database data as String objects using the getString() getter methods. Creating Text Fields with Account Information Once the account list and Get Account button have been created, they are added to a panel, which is added to the application frame. After that step, our code creates five JTextField controls to hold the five column values from a row in the acc_acc table. These controls are added to a second panel, which is also added to the application frame.
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