android.support.v4.view.ViewPager cannot be cast to com.custom.NoScrollViewPager 解决方案

最近在写一个Android APP的过程中，由于用到了禁止滑动的Viewpager，我采用了前辈大牛提供的解决方案，

网址如下：https://blog.csdn.net/yilei0033/article/details/79444099

简单来说，是自定义一个继承ViewPager的类：NoScrollViewPager，重写了onInterceptTouchEvent(MotionEvent event)及添加了setNoScroll(boolean noScroll)方法。在运行时，报出了这样的一个异常：

01-20 11:12:12.890: E/AndroidRuntime(32097): Caused by: java.lang.ClassCastException: android.support.v4.view.ViewPager cannot be cast to com.example.library.NoScrollViewPager

这个异常，我记得在我写上一个APP的时候就遇到过，这次又被困扰了一段时间，特此写下来提醒自己。

先附上我项目中的代码：

首先，是自定义的NoScrollViewPager，继承了android.support.v4.view.ViewPager 。

NoScrollViewPager.java
public class NoScrollViewPager extends android.support.v4.view.ViewPager {
	private boolean isCanScroll = false;

	public NoScrollViewPager(Context context) {
		super(context);
		// TODO Auto-generated constructor stub
	}

	public NoScrollViewPager(Context context, AttributeSet attrs) {
		super(context, attrs);
	}

	public void setScanScroll(boolean isCanScroll) {
		this.isCanScroll = isCanScroll;
	}

	@Override
	public void scrollTo(int x, int y) {
		super.scrollTo(x, y);
	}

	@SuppressLint("ClickableViewAccessibility")
	@Override
	public boolean onTouchEvent(MotionEvent arg0) {
		// TODO Auto-generated method stub
		if (isCanScroll) {
			return super.onTouchEvent(arg0);
		} else {
			return false;
		}

	}

	@Override
	public boolean onInterceptTouchEvent(MotionEvent arg0) {
		// TODO Auto-generated method stub
		if (isCanScroll) {
			return super.onInterceptTouchEvent(arg0);
		} else {
			return false;
		}
	}

	@Override
	public void setCurrentItem(int item, boolean smoothScroll) {
		// TODO Auto-generated method stub
		super.setCurrentItem(item, smoothScroll);
	}

	@Override
	public void setCurrentItem(int item) {
		// TODO Auto-generated method stub
		super.setCurrentItem(item, false);
	}
}

 接下来，是我自定义的ViewPagerFragment，构造函数中以layout的id为参数绑定布局文件，从而实现代码复用。

其中，mViewPager是android.support.v4.view.ViewPager类型。

SingleViewPagerFragment.java
public class SingleViewPagerFragment extends Fragment {

	// TabLayout
	protected TabLayout mTabLayout;
	// ViewPager
	protected ViewPager mViewPager;
	// Title
	protected List mTitle;
	// Fragment
	protected List mFragment;
	// View
	protected View view;

	private int layout;
	
	public SingleViewPagerFragment(int layout) {
		// TODO Auto-generated constructor stub
		this.layout = layout;
	}
	
	public SingleViewPagerFragment() {
		// TODO Auto-generated constructor stub
	}
	
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		// this.requestWindowFeature(Window.FEATURE_NO_TITLE);//去掉标题栏
	}

	/*
	 * 初始化数据
	 */
	@SuppressLint("InflateParams")
	@Override
	public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
		// TODO Auto-generated method stub
		if (view != null) {
			ViewGroup parent = (ViewGroup) view.getParent();
			if (parent != null) {
				parent.removeView(view);
			}
			return view;
		}
		view = inflater.inflate(layout, null);

		initData();
		initView(view);
		return view;
	}
	
	protected void initData() {

		mTitle = new ArrayList();
		mFragment = new ArrayList();
		// DatabaseQuery.CollegeMkdirs();//创建下载文件的目录
	}

	/*
	 * 初始化view
	 */
	protected void initView(View v) {

	}
}

下面是layout文件：

 最后，是具体的ViewPager，继承了我自定义的SingleViewPagerFragment，并在initView中，使用以下代码：

mViewPager = (NoScrollViewPager) v.findViewById(R.id.main_ViewPager);

获取NoScroolViewPager。结果出现了题目所述异常。

//MainViewPagerFragment.java
public class MainViewPagerFragment extends SingleViewPagerFragment {
	public MainViewPagerFragment(int layout) {
		super(layout);
		// TODO Auto-generated constructor stub
	}

	@Override
	public void onCreate(Bundle savedInstanceState) {
		// TODO Auto-generated method stub
		super.onCreate(savedInstanceState);
	}

	public MainViewPagerFragment() {
		// TODO Auto-generated constructor stub
	}
	
	protected void initData() {
		super.initData();
		mTitle.add("发 单");
		mTitle.add("抢 单");
		mTitle.add("我 的");

		mFragment.add(new DeliverFragment());
		mFragment.add(new ReceiveFragment());
		mFragment.add(new UserFragment());
		// DatabaseQuery.CollegeMkdirs();//创建下载文件的目录
	}

	@Override
	protected void initView(View v) {
		// TODO Auto-generated method stub
		mTabLayout = (TabLayout) v.findViewById(R.id.main_TabLayout);
		mViewPager = (NoScrollViewPager) v.findViewById(R.id.main_ViewPager);
		super.initView(v);
		// 添加适配器
		MainPagerAdapter myFragmentPagerAdapter = new MainPagerAdapter(getActivity().getSupportFragmentManager(),
				mFragment, mTitle, this.getActivity());
		mViewPager.setAdapter(myFragmentPagerAdapter);
		mViewPager.setOffscreenPageLimit(mTabLayout.getTabCount());

		// mViewPager
		mViewPager.addOnPageChangeListener(new OnPageChangeListener() {

			@Override
			public void onPageSelected(int arg0) {
				// TODO Auto-generated method stub
				mTabLayout.getTabAt(arg0).select();
			}

			@Override
			public void onPageScrolled(int arg0, float arg1, int arg2) {
				// TODO Auto-generated method stub

			}

			@Override
			public void onPageScrollStateChanged(int arg0) {
				// TODO Auto-generated method stub

			}
		});

		mTabLayout.setupWithViewPager(mViewPager);
		for (int i = 0; i < mTabLayout.getTabCount(); i++) {
			mTabLayout.getTabAt(i).setCustomView(myFragmentPagerAdapter.getTabView(i));
		}
		mTabLayout.setSelectedTabIndicatorColor(Color.WHITE);
		// this.reflex(mTabLayout);
		mTabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {

			@SuppressWarnings("deprecation")
			@Override
			public void onTabUnselected(Tab tab) {
				// TODO Auto-generated method stub
				switch (tab.getPosition()) {
				case 0:
					tab.getCustomView().findViewById(R.id.item_text).setBackgroundResource(R.drawable.empty_tab);
					break;
				case 1:
					tab.getCustomView().findViewById(R.id.item_text).setBackgroundResource(R.drawable.empty_tab);
					break;
				case 2:
					tab.getCustomView().findViewById(R.id.item_text).setBackgroundResource(R.drawable.empty_tab);
					break;
				}
				TextView textView = (TextView) tab.getCustomView().findViewById(R.id.item_text);
				textView.setTextColor(getResources().getColor(R.color.colorAccent));
			}

			@SuppressWarnings("deprecation")
			@Override
			public void onTabSelected(Tab tab) {
				// TODO Auto-generated method stub
				switch (tab.getPosition()) {
				case 0:
					tab.getCustomView().findViewById(R.id.item_text).setBackgroundResource(R.drawable.tab0);
					break;
				case 1:
					tab.getCustomView().findViewById(R.id.item_text).setBackgroundResource(R.drawable.tab1);
					break;
				case 2:
					tab.getCustomView().findViewById(R.id.item_text).setBackgroundResource(R.drawable.tab2);
					break;
				}
				TextView textView = (TextView) tab.getCustomView().findViewById(R.id.item_text);
				textView.setTextColor(getResources().getColor(R.color.colorSelected));
				mViewPager.setCurrentItem(tab.getPosition());
			}

			@Override
			public void onTabReselected(Tab arg0) {
				// TODO Auto-generated method stub

			}
		});
		mViewPager.setCurrentItem(0);
		mTabLayout.getTabAt(0).select();
	}
}

引发异常的原因，是我仅仅在Fragment中获取NoScroolViewPager时将之强制转化，并没有在layout中将android.support.v4.view.ViewPager替换为我自定义的NoScrollViewPager，正确的layout文件如下:

弱智错误。。。。再也不想被它困扰！