接口回调Demo

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设置接口

ViewPager mViewPager.setOnPageChangeListener(listener);OnPageChangeListener listener = new OnPageChangeListener() {        @Override        public void onPageScrolled(int position, float positionOffset,                int positionOffsetPixels) {            // TODO Auto-generated method stub        }        @Override        public void onPageSelected(int position) {            // TODO Auto-generated method stub        }        @Override        public void onPageScrollStateChanged(int state) {            // TODO Auto-generated method stub        }    };

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定义接口

public interface OnPageChangeListener {  void onPageScrolled(int position, float positionOffset, int positionOffsetPixels); void onPageSelected(int position);  void onPageScrollStateChanged(int state);}

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回调接口

 private void dispatchOnScrollStateChanged(int state) {        if (mOnPageChangeListener != null) {            mOnPageChangeListener.onPageScrollStateChanged(state);        }        if (mOnPageChangeListeners != null) {            for (int i = 0, z = mOnPageChangeListeners.size(); i < z; i++) {                OnPageChangeListener listener = mOnPageChangeListeners.get(i);                if (listener != null) {                    listener.onPageScrollStateChanged(state);                }            }        }        if (mInternalPageChangeListener != null) {            mInternalPageChangeListener.onPageScrollStateChanged(state);        }    }