If is not executed unless System.out.println is used or while debugging [duplicate]

We are developing a Simulator with Students with Java and Swing. The Problem we have is that after a Button Click in the Simulator.java the variable for private static boolean startButton change too true. After this the "if" should start doing their job, but that is not the case.

I have this Code Block in my Brain.java:

public class Brain
{
    // ==========================================================

    /*
     * This is the Part of Port A
     */
    // Tris for Port A | ARRAY VALUE 0
    private static boolean[] port_A_Tris_Checkboxes = new boolean[8];

    // PINs | ARRAY VALUE 1
    private static boolean[] port_A_Pins_Checkboxes = new boolean[5];

    /*
     * This is the Part of Port B
     */
    // Tris for Port B | ARRAY VALUE 2
    private static boolean[] port_B_Tris_Checkboxes = new boolean[8];

    // PINs | ARRAY VALUE 3
    private static boolean[] port_B_Pins_Checkboxes = new boolean[8];

    // ==========================================================

    /*
     * This is the Part of the Watchdog
     */
    private static boolean watchdogCheckbox;

    // ==========================================================

    /*
     * This is the Part of the Reset Button
     */
    private static boolean resetButton;

    // ==========================================================

    /*
     * This is the Part of the Einzelschritt Button
     */
    private static boolean einzelschrittButton;

    // ==========================================================

    /*
     * This is the Part of the Start Button
     */
    private static boolean startButton = false;

    // ==========================================================

    /*
     * This is the Part of the Stop Button
     */
    private static boolean stopButton = false;

    // ==========================================================

    public static void main(String[] args)
    {
        // startet das GUI
        Simulator.main(args);
        while (true) {

            if ((startButton == true) && (stopButton == false)) {

                // Do one step of the program
                Steuerwerk.runCommand(Decoder.decode(Simulator.getProgramMemory()
                        .getProgramMemory()[ProgramCounter.getProgramCounter()]),
                        Simulator.getProgramMemory().getProgramMemory()[ProgramCounter
                                .getProgramCounter()]);
                System.out.println(W_Register.getArgument());

            } else if (getStart() && getStop()) {

                /*
                 * If program has already started and the stop button was pressed,
                 * stop the program
                 */
                setStart(false);
                setStop(false);

            } else if (getStop()) {

                // No reason to save stopping of program if it didn't even start yet
                setStop(false);

            } else if (getEinzelschritt()) {

                // Do one step of the program
                Steuerwerk.runCommand(Decoder.decode(Simulator.getProgramMemory()
                        .getProgramMemory()[ProgramCounter.getProgramCounter()]),
                        Simulator.getProgramMemory().getProgramMemory()[ProgramCounter
                                .getProgramCounter()]);
                System.out.println(W_Register.getArgument());
                setEinzelschritt(false);
            }
        }

    }

    // ==========================================================

    /**
     * 
     * @param index : Checkbox value, true if checkbox has been marked
     * @param whichArray : Value that say which ArrayIndex is checked in which
     *        Array
     * 
     *        Diese Methode wird die in der GUI aktivierten Checkboxen hier in
     *        der Programm Logik vermerken sodass diese dann für die weitere
     *        Abarbeitung nach User wunsch geschehen und mit berüchsichtigung der
     *        aktivierten Checkboxen des Users
     */
    public static void setChechboxesForTrisOrPinBoolean(int index,
            int whichArray)
    {
        switch (whichArray) {
        case 0: {
            port_A_Tris_Checkboxes[index] = !port_A_Tris_Checkboxes[index];
            break;
        }
        case 1: {
            port_A_Pins_Checkboxes[index] = !port_A_Pins_Checkboxes[index];
            break;
        }
        case 2: {
            port_B_Tris_Checkboxes[index] = !port_B_Tris_Checkboxes[index];
            break;
        }
        case 3: {
            port_B_Pins_Checkboxes[index] = !port_B_Pins_Checkboxes[index];
            break;
        }
        default:
            throw new IllegalArgumentException("Unexpected value: " + whichArray);
        }
    }

    // ==========================================================

    /**
     * Diese methode wird die Aktivierung der Watchog Checkbox berücksichtigen
     * und eben dann auch vermerken
     */
    public static void setCheckboxForWatchdog()
    {
        watchdogCheckbox = !watchdogCheckbox;
    }

    // ==========================================================

    /*
     * The Set Method for the Reset Button
     */
    public static void setReset(boolean value)
    {
        if (value == true) {
            resetButton = true;
        } else {
            resetButton = false;
        }
    }

    /*
     * Get Method for the Reset Button Value
     */
    public static boolean getReset()
    {
        return resetButton;
    }

    // ==========================================================

    /*
     * The Set Method for the Einzelschritt Button
     */
    public static void setEinzelschritt(boolean value)
    {
        if (value == true) {
            einzelschrittButton = true;
        } else {
            einzelschrittButton = false;
        }
    }

    /*
     * Get Method for the Einzelschritt Button Value
     */
    public static boolean getEinzelschritt()
    {
        return einzelschrittButton;
    }

    // ==========================================================

    /*
     * The Set Method for the Start Button
     */
    public static void setStart(boolean value)
    {
        if (value == true) {
            startButton = true;
        } else {
            startButton = false;
        }
    }

    /*
     * Get Method for the Start Button Value
     */
    public static boolean getStart()
    {
        return startButton;
    }

    // ==========================================================

    /*
     * The Set Method for the Stop Button
     */
    public static void setStop(boolean value)
    {
        if (value == true) {
            stopButton = true;
        } else {
            stopButton = false;
        }
    }

    /*
     * Get Method for the Stop Button Value
     */
    public static boolean getStop()
    {
        return stopButton;
    }

    // ==========================================================
}

the other Part is my Simulator:

JButton btnStart = new JButton("START");
        btnStart.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e)
            {
                // TODO Auto-generated method stub
                System.out.println("Pressed");
                Brain.setStart(true);
            }
        });

The funny thing is that only if we add a System.out.println() or we Debug... it starts the if.