<android.support.v4.view.ViewPager
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/my_view_pager"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
</android.support.v4.view.ViewPager>

java.lang.RuntimeException: Unable to start activity android.view.InflateException: Binary XML file line #28: Error inflating class ViewPager
Caused by: java.lang.ClassNotFoundException: Didn't find class "android.view.ViewPager" on path: DexPathList

import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
 
// For this demonstration I'm using using a custom frame layout to hold the view pager.
public class MyFrameLayout extends FrameLayout {
    // Views
    private MyViewPagerAdapter myViewPagerAdapter; // View Pager Adapter
    private ViewPager myViewPager; // View Pager
 
    // Layout inflater for creating views
    private LayoutInflater inflater;
 
    // FrameLayout Constructors
    public MyFrameLayout(Context context) { super(context); }
    public MyFrameLayout(Context context, AttributeSet attrs) { super(context, attrs); }
    public MyFrameLayout(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); }
 
    // Sample initializtion method to setup the views when ready
    public void initialize() {
    	// Grab a reference to the ViewPager
    	myViewPager = (ViewPager) findViewById(R.id.my_view_pager);
 
    	// Construct a new PagerAdapter to manage the pages of the ViewPager
    	myViewPagerAdapter = new MyViewPagerAdapter(); // Inner class - see below
 
    	// Set the ViewPagers adapter
    	myViewPager.setAdapter(myViewPagerAdapter);
 
    	// Construct the layout inflater
    	this.inflater = (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }
 
    // Inner subclass of PagerAdapter to manage the ViewPager views
    class MyViewPagerAdapter extends PagerAdapter {
    	// Constructor
        public MyViewPagerAdapter() {}
 
        // Required Override for the ViewPager to function properly.
        // The value returned here is used referenced by the ViewPager. If getCount() returns 0, no views will be created.
        // This is best used with a data set. Set this to return the size of your data set.
        // Using a default value of 5 to display 5 pages for this demonstration.
        @Override public int getCount() { return 5; }
 
        // Required Override for the ViewPager to function properly.
        // Determines whether a page View is associated with a specific key object as returned by instantiateItem(ViewGroup, int). 
        @Override public boolean isViewFromObject(View view, Object o) { return view == o; }
 
        // Required Override for the ViewPager to function properly.
        // Removes a page for the given position. Called automatically by ViewPager as needed.
        @Override
        public void destroyItem(ViewGroup container, int position, Object object) { container.removeView((View) object); }
 
        // Required Override for the ViewPager to function properly.
        // Creates pages for the given position automatically.
        // This function will fire automatically as required. On instantiation this will fire twice, once for
        // page one, once for page two. As users scroll it will fire to ensure views exist ahead and behind the active
        // item. This function was confusing to me initially.
        @Override
        public Object instantiateItem(ViewGroup container, int position) {
            // Inflate (and modify) the desired layout to add to the ViewPager.
            FrameLayout item = (FrameLayout) inflater.inflate(R.layout.view_to_add_to, container, false);
 
            // Add the inflated item to the ViewPager
            container.addView(item);
 
            // Ensure the item created and added to the container is returned
            return item;
        }
 
        // Used internally by the adapter when calling notifyDataSetChanged(). This method is referenced during this
        // call. Returning POSITION_NONE cases the previously created views to be destroyed and new ones created.
        // This was a big gotcha for me when modifying the data set to remove or add views from the ViewPager.
        @Override
        public int getItemPosition(Object object) { return POSITION_NONE; }
    }
}