如何在匿名实现中删除侦听器

Question

使用匿名实现时，无法理解如何阻止耐心的课程收听主题。

我尝试使用Subject变量，以便可以在reactToChange（）中访问它；但不知道下一步该怎么做。

  import java.beans.PropertyChangeEvent;
    
    public class Patient
    {
      private int ticketNumber;
    
      public Patient(int ticketNumber, Subject subject)
      {
        this.ticketNumber = ticketNumber;    
        subject.addListener(this::reactToChange);  // implementing anonymous implementation
      }
    
      private void reactToChange(PropertyChangeEvent event)
      {
        int newValue = (Integer) event.getNewValue();    
        if(newValue == ticketNumber){
          System.out.println("Patient " + ticketNumber + " goes to the doctor's room");


          //need to delete this listener here

        } else {
          System.out.println("Patient " + ticketNumber + " goes back to looking at phone");
        }
      }
    
    }

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