Why Is My TextField Flashing Only Once? (Swing Timer and ActionListener Issue)

Problem Handling: Flash Behaviour in a Swing Timer

In the provided Java code, a timer is configured with an ActionListener to update the background color of a text field in an alternating sequence. While the timer triggers the ActionListener appropriately, the color change is only observed in the initial iteration.

Root Cause

Your primary error lies in the custom implementation of your ActionListener. Specifically, the following two issues hinder proper functionality:

1. Assignment of 'flasher' variable: The code doesn't initialize the 'flasher' variable, so it operates with an uninitialized value.
2. Lack of GUI Update: Swing components must be updated within the Event Dispatch Thread (EDT). Without this, screen elements may not reflect the desired changes.

Resolution

Implement the following modifications:

1. Initialization of 'flasher': Include private boolean flasher = false; at the top of the Flash class to initialize the flasher variable.
2. Updating GUI in EDT: Within the actionPerformed method, invoke SwingUtilities.invokeLater() to place the color change within the EDT. Update the code as follows:

<code class="java">@Override
public void actionPerformed(ActionEvent evt)
{
    SwingUtilities.invokeLater(new Runnable() {
        @Override
        public void run() {
            if (flasher)
            {
                SpreademPanel.historyPnl.NameTxt.setBackground(Color.white);
            }
            else
            {
                SpreademPanel.historyPnl.NameTxt.setBackground(Color.pink);
            }
            flasher = !flasher;
        }
    });
} //actionPerformed</code>

By applying these changes, the timer will now effectively update the text field's background color on a continuous basis.

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