Is this valid?

Is it okay to replace the deprecated method:
loadThread.stop();

with

loadThread = null;
?

No. Here's what the 1.4 API docs have to say about it.

Code:

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What should I use instead of Thread.stop?

Most uses of stop should be replaced by code that simply modifies some variable to indicate that the target thread should stop running. The target thread should check this variable regularly, and return from its run method in an orderly fashion if the variable indicates that it is to stop running. (This is the approach that JavaSoft's Tutorial has always recommended.) To ensure prompt communication of the stop-request, the variable must be volatile (or access to the variable must be synchronized).

For example, suppose your applet contains the following start, stop and run methods:

    private Thread blinker;

    public void start() {
        blinker = new Thread(this);
        blinker.start();
    }

    public void stop() {
        blinker.stop();  // UNSAFE!
    }

    public void run() {
        Thread thisThread = Thread.currentThread();
        while (true) {
            try {
                thisThread.sleep(interval);
            } catch (InterruptedException e){
            }
            repaint();
        }
    }

You can avoid the use of Thread.stop by replacing the applet's stop and run methods with:

    private volatile Thread blinker;

    public void stop() {
        blinker = null;
    }

    public void run() {
        Thread thisThread = Thread.currentThread();
        while (blinker == thisThread) {
            try {
                thisThread.sleep(interval);
            } catch (InterruptedException e){
            }
            repaint();
        }
    }

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