Java Programming. <br> Using Swing Methods I am having trouble setting the code

Question

Java Programming. <br>

Using Swing Methods

I am having trouble setting the code up using Swing and can use any insight. If you able to provide the solution that would be appreciated.

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Write a program that will process students entering the cafeteria. In a perfect world, the students would hold thier student ID cards under a barcode reader. In this application, the student ID will be entered. The attendant will then be shown the student's name, a picture of the student (for verification) and whether the student has a meal left on their weekly meal plan (indicated by a green square on the screen if yes or a red square if now)<br>

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The students.txt file will be provided in the following format:<br>

first name<br>

last name<br>

student ID number (6 digits)<br>

number of meals remaining<br>

the name of the student's picture file<br>

The picture file is included as well.<br>

In this Java code we need to take a student id number as input, look up that id number in a file, make sure the exceptions are handled, if number is not in the file display a message, get picture file name from student record, display student name and picture, check how many meals are left on plan, If none, display red box, If one or more display green box, subract 1 meal, and provide an exit button.

Explanation / Answer

A Swing timer (an instance of javax.swing.Timer) fires one or more action events after a specified delay. Don't confuse Swing timers with the general-purpose timer facility that was added to the java.util package in release 1.3. This page describes only Swing timers. In general, we recommend using Swing timers rather than general-purpose timers for GUI-related tasks because Swing timers all share the same, pre-existing timer thread and the GUI-related task automatically executes on the event-dispatch thread. However, you might use a general-purpose timer if you don't plan on touching the GUI from the timer, or need to perform lengthy processing. You can use Swing timers in two ways: To perform a task once, after a delay. For example, the tool tip manager uses Swing timers to determine when to show a tool tip and when to hide it. To perform a task repeatedly. For example, you might perform animation or update a component that displays progress toward a goal. Swing timers are very easy to use. When you create the timer, you specify an action listener to be notified when the timer "goes off". The actionPerformed method in this listener should contain the code for whatever task you need to be performed. When you create the timer, you also specify the number of milliseconds between timer firings. If you want the timer to go off only once, you can invoke setRepeats(false) on the timer. To start the timer, call its start method. To suspend it, call stop. Note that the Swing timer's task is performed in the event dispatch thread. This means that the task can safely manipulate components, but it also means that the task should execute quickly. If the task might take a while to execute, then consider using a SwingWorker instead of or in addition to the timer. See Concurrency in Swing for instructions about using the SwingWorker class and information on using Swing components in multi-threaded programs. Let's look at an example of using a timer to periodically update a component. The TumbleItem applet uses a timer to update its display at regular intervals. (To see this applet running, go to How to Make Applets. This applet begins by creating and starting a timer: timer = new Timer(speed, this); timer.setInitialDelay(pause); timer.start(); The speed and pause variables represent applet parameters; as configured on the other page, these are 100 and 1900 respectively, so that the first timer event will occur in approximately 1.9 seconds, and recur every 0.1 seconds. By specifying this as the second argument to the Timer constructor, TumbleItem specifies that it is the action listener for timer events. After starting the timer, TumbleItem begins loading a series of images in a background thread. Meanwhile, the timer events begin to occur, causing the actionPerformed method to execute: public void actionPerformed(ActionEvent e) { //If still loading, can't animate. if (!worker.isDone()) { return; } loopslot++; if (loopslot >= nimgs) { loopslot = 0; off += offset; if (off < 0) { off = width - maxWidth; } else if (off + maxWidth > width) { off = 0; } } animator.repaint(); if (loopslot == nimgs - 1) { timer.restart(); } } Until the images are loaded, worker.isDone returns false, so timer events are effectively ignored. The first part of the event handling code simply sets values that are employed in the animation control's paintComponent method: loopslot (the index of the next graphic in the animation) and off (the horizontal offset of the next graphic). Eventually, loopslot will reach the end of the image array and start over. When this happens, the code at the end of actionPerformed restarts the timer. Doing this causes a short delay before the animation sequence begins again.

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