Use reflect to control toast's show and hide, but not work

I want to control a toast's show and hide action, so I use reflect to get show and hide method through variable mTN, but the toast not show when I call showMethod, that's the code:

1. Creation of toast:

   final TextView tView = new TextView(MainActivity.this);
   tView.setText("ReflectToast !!!");
   tView.setBackgroundColor(getResources().getColor(R.color.float_window_color2));
   toast = new ReflectToast(MainActivity.this, tView);
   
   

2. calling of show method:

   mFloatBtn = findViewById(R.id.startFloatWindow);
   mFloatBtn.setOnClickListener(new View.OnClickListener() {
       @Override
       public void onClick(View v) {
           if(isShown){
               toast.cancel();
               isShown = false;
           }else{
               toast.show();
               isShown = true;
           }
       }
   });
   
   

3. Definition of Toast class: class ReflectToast {

   Context mContext;
   
   private Toast mToast;
   private Field field;
   private Object obj;
   private Method showMethod, hideMethod;
   
   public ReflectToast(Context c, View v) {
       this.mContext = c;
       mToast = new Toast(mContext);
       mToast.setView(v);
   
       reflectionTN();
   }
   
   public void show() {
       try {
           Log.v("toast", "show enter");
           showMethod.invoke(obj, new  Object[]{});
       } catch (Exception e) {
           e.printStackTrace();
       }
   }
   
   public void cancel() {
       try {
           hideMethod.invoke(obj, new  Object[]{});
       } catch (Exception e) {
           e.printStackTrace();
       }
   }
   
   private void reflectionTN() {
       try {
           field = mToast.getClass().getDeclaredField("mTN");
           field.setAccessible(true);
           obj = field.get(mToast);
           showMethod = obj.getClass().getDeclaredMethod("show", new  Class[ 0 ]);
           hideMethod = obj.getClass().getDeclaredMethod("hide", new  Class[ 0 ]);
       } catch (Exception e) {
           e.printStackTrace();
       }
   }
   
   

   }