455_ViewPager的notify方法

ViewPager的notify方法

Viewpager調用notifyDataSetChanged()是無效的

為什麼?????????????????????????

這個問題真的特别蛋疼

PagerAdapter adapter = new PagerAdapter(){...};

viewPager.setAdapter(adapter);

adapter.notifyDataSetChanged();

罪惡源頭就是這個PagerAdapter

看看源碼把

    public void notifyDataSetChanged() {

        synchronized (this) {

            if (mViewPagerObserver != null) {

                mViewPagerObserver.onChanged();

            }

        }

        mObservable.notifyChanged();

    }

注釋:

如果adapter關聯的data變了,調用這個方法,那麼關聯的view就更新了

bullshit!!!

根本沒有更新.

裡面是一個同步,然後mObservable.notifyChanged()

看看這個notifyChanged()

    public void notifyChanged() {

        synchronized(mObservers) {

            // since onChanged() is implemented by the app, it could do anything, including

            // removing itself from {@link mObservers} - and that could cause problems if

            // an iterator is used on the ArrayList {@link mObservers}.

            // to avoid such problems, just march thru the list in the reverse order.

            for (int i = mObservers.size() - 1; i >= 0; i--) {

                mObservers.get(i).onChanged();

            }

        }

    }

解決方案:

        ViewPager vp_content = (ViewPager) findViewById(R.id.vp_content);

        adapter = new FragmentStatePagerAdapter(getSupportFragmentManager()) {

            @Override

            public Fragment getItem(int position) {

                return list.get(position);

            }

            @Override

            public int getCount() {

                return list.size();

            }

            @Override

            public int getItemPosition(Object object) {

                return POSITION_NONE;

            }

        };

        vp_content.setAdapter(adapter);

試試看

來兩個button

    public void remove(View view) {

        list.remove(0);

    }

    public void update(View view) {

        adapter.notifyDataSetChanged();

    }

試驗成功.