线程不会停止使用按钮(多线程)

我想使用另一个类中的停止按钮来停止多个线程。我尝试使用布尔函数停止线程,但它无法工作。当用户单击停止按钮时,线程仍在运行,我该如何解决这个问题?

这是主课

public class ElevatorSystem extends javax.swing.JFrame {
    public static int currentFloor = 1;

    Thread ElevatorMove = null;
    Thread PeopleMove = null;
    static Thread RandomPeople = null;
    Thread MAIN_THREAD = new Thread(new Main_Thread());
    private Main_Thread mt = new Main_Thread();
    ...

    public ElevatorSystem() {
        initComponents();
        randWeight();
        this.setResizable(false);
        if(pplw.isEmpty())
            elev_weight = 0;
        else{
            for(int s:pplw)
                elev_weight += s;

        }
        RandomPeople = new Thread(new Randomize_People(EntryFloor1,EntryFloor2,EntryFloor3,EntryFloor4,EntryFloor5));
        RandomPeople.setPriority(Thread.MAX_PRIORITY-1);
    //Start Adding peeoples
        RandomPeople.start();
    }

    ...
    private void btnStopActionPerformed(java.awt.event.ActionEvent evt) {                                        
        //not working...
        if(MAIN_THREAD.isAlive()){
            try {
                mt.stopThread();
            } catch (InterruptedException ex) {
                Logger.getLogger(ElevatorSystem.class.getName()).log(Level.SEVERE, null, ex);
            }
        }else{
            this.setEnabled(false);
            JOptionPane.showMessageDialog(this,"Thread Not Running!","Thread Not Running!",JOptionPane.INFORMATION_MESSAGE);
            this.setEnabled(true);
        }
    }   
}

这是线程

class Main_Thread implements Runnable{
    ....
    private final Object ElevatorSystem = new Object();
    private boolean pauseThreadFlag = false;

    Main_Thread(){

    }

    Main_Thread(
        JTextField EntryFloor1, JTextField ExitFloor1,
        JTextField EntryFloor2, JTextField ExitFloor2,
        JTextField EntryFloor3, JTextField ExitFloor3,
        JTextField EntryFloor4, JTextField ExitFloor4,
        JTextField EntryFloor5, JTextField ExitFloor5,
        JTextField Ceiling,

        JTextArea Elev1,   JPanel Elev1Container,

        String Elevator_Status, int currentFloor,int elev_weight, ArrayList pplw
    ){
        this.EntryFloor1 = EntryFloor1; this.ExitFloor1 = ExitFloor1;
        this.EntryFloor2 = EntryFloor2; this.ExitFloor2 = ExitFloor2;
        this.EntryFloor3 = EntryFloor3; this.ExitFloor3 = ExitFloor3;
        this.EntryFloor4 = EntryFloor4; this.ExitFloor4 = ExitFloor4;
        this.EntryFloor5 = EntryFloor5; this.ExitFloor5 = ExitFloor5;

        this.Elev1 = Elev1;
        this.Elev1Container = Elev1Container;

        this.Elevator_Status = Elevator_Status;
        this.currentFloor = currentFloor;

        this.elev_weight = elev_weight;

        this.pplw.addAll(pplw);
    }
    @Override
    public void run() {
        System.out.println("Running...");
        System.out.println("Inside Weight: "+pplw);
        while(true){
            checkForPaused();
            //whole process
       }
    }

    private void checkForPaused() {
       synchronized (ElevatorSystem) {
           while (pauseThreadFlag) {
               try {
                   ElevatorSystem.wait();
               } catch (Exception e) {}
           }
       }
    }

    public void stopThread() throws InterruptedException {
        pauseThreadFlag = true;
    }
}

class People_Move implements Runnable{
    ...
}

class Elevator_move_UP implements Runnable{
    ...
}

class Elevator_move_DOWN implements Runnable{
    ...
}

class Randomize_People implements Runnable{
    ...
}