The method of ViewPage to judge the left and right sliding direction in Android programming

This paper describes the ViewPage programming Android to determine the left and right sliding direction of the method. To share for your reference, the details are as follows:

package com.meityitian.app.views;
import android.content.Context; 
import android.support.v4.view.ViewPager; 
import android.util.AttributeSet; 
import android.util.Log; 
import com.meityitian.app.utils.Debug; 
/** 
 *  Overrides, adding a method to determine the direction of the slide  
 * @author zxy 
 * 
 */ 
public class meityitianViewPager extends ViewPager { 
 private boolean left = false; 
 private boolean right = false; 
 private boolean isScrolling = false; 
 private int lastValue = -1; 
 private ChangeViewCallback changeViewCallback = null; 
 public meityitianViewPager(Context context, AttributeSet attrs) { 
  super(context, attrs); 
  init(); 
 } 
 public meityitianViewPager(Context context) { 
  super(context); 
  init(); 
 } 
 /** 
  * init method . 
*/ 
 private void init() { 
  setOnPageChangeListener(listener); 
 } 
 /** 
  * listener ,to get move direction . 
*/ 
 public OnPageChangeListener listener = new OnPageChangeListener() { 
  @Override 
  public void onPageScrollStateChanged(int arg0) { 
   if (arg0 == 1) { 
    isScrolling = true; 
   } else { 
    isScrolling = false; 
   } 
   Debug.infoByTag("meityitianViewPager", 
     "meityitianViewPager onPageScrollStateChanged : arg0:" 
       + arg0); 
   if (arg0 == 2) { 
    Debug.infoByTag("meityitianViewPager", 
      "meityitianViewPager onPageScrollStateChanged direction left ? " 
        + left); 
    Debug.infoByTag("meityitianViewPager", 
      "meityitianViewPager onPageScrollStateChanged direction right ? " 
        + right); 
    //notify .... 
    if(changeViewCallback!=null){ 
     changeViewCallback.changeView(left, right); 
    } 
    right = left = false; 
   } 
  } 
  @Override 
  public void onPageScrolled(int arg0, float arg1, int arg2) { 
   if (isScrolling) { 
    if (lastValue > arg2) { 
     //  Decrement, slide to the right  
     right = true; 
     left = false; 
    } else if (lastValue < arg2) { 
     //  Decrement, slide to the right  
     right = false; 
     left = true; 
    } else if (lastValue == arg2) { 
     right = left = false; 
    } 
   } 
   Log.i("meityitianViewPager", 
     "meityitianViewPager onPageScrolled last :arg2 ," 
       + lastValue + ":" + arg2); 
   lastValue = arg2; 
  } 
  @Override 
  public void onPageSelected(int arg0) { 
   if(changeViewCallback!=null){ 
    changeViewCallback.getCurrentPageIndex(arg0); 
   } 
  } 
 }; 
 /** 
  *  To get whether to slide to the right  
  * @return true  For the right sliding  
*/ 
 public boolean getMoveRight(){ 
  return right; 
 } 
 /** 
  *  Get whether to slide to the left  
  * @return true  Slide for left  
*/ 
 public boolean getMoveLeft(){ 
  return left; 
 } 
 /** 
  *  Slide status change callback  
  * @author zxy 
  * 
*/ 
 public interface ChangeViewCallback{ 
  /** 
   *  Switch the view   ? Determined by the left and right  .  
   * @param left 
   * @param right 
*/ 
  public void changeView(boolean left,boolean right); 
  public void getCurrentPageIndex(int index); 
 } 
 /** 
  * set ... 
  * @param callback 
*/ 
 public void setChangeViewCallback(ChangeViewCallback callback){ 
  changeViewCallback = callback; 
 } 
}

I hope this article has been helpful in Android programming.