BaseAdapter导致notifyDataSetChanged()无效的四个原因及处理方法

大家好，又见面了，我是你们的朋友全栈君。

前一段时间在做一个项目的时候遇到了一个关于BaseAdapter的notifyDataSetChanged()方法无效问题，当时在网上搜了一个解决方法，今天又遇到了一个类似的问题，我在这里做个记录，防止以后再次发生，或者其他朋友再次遇到。

一、ScrollView中嵌套ListView或GridView

原因：两个的滚动监听冲突

解决方法：重写ListView或GridView

package com.meritit.lottery.view;

import android.content.Context;
import android.util.AttributeSet;
import android.widget.ListView;

public class SerialListView extends ListView {

	public SerialListView(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);
		// TODO Auto-generated constructor stub
	}

	public SerialListView(Context context, AttributeSet attrs) {
		super(context, attrs);
		// TODO Auto-generated constructor stub
	}

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

	/**
	 * 为了取消滚动效果，可以放入滚动组建中重写了此方法
	 */
	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
		int expandSpec = MeasureSpec.makeMeasureSpec(Integer.MAX_VALUE >> 2,
				MeasureSpec.AT_MOST);
		super.onMeasure(widthMeasureSpec, expandSpec);
	}

}

二、ListView或GridView的外部容器重写onTouchEvent(MotionEvent event)方法

详细请看：http://blog.csdn.net/xxxzhi/article/details/12314775

这类问题解决方法很简单，只需要onTouchEvent返回false即可

例如：

	@Override
	public boolean onTouchEvent(MotionEvent event) {
		// TODO Auto-generated method stub           	            
	        final int action = event.getAction();    
	        final float x = event.getX();    
	        final float y = event.getY();    
	            
	        switch (action) {    
	        case MotionEvent.ACTION_DOWN: 	
	        	System.out.println("父类点击onTouchEvent");
	        	  Log.i("", "onTouchEvent  ACTION_DOWN");	        	  
	        	if (mVelocityTracker == null) {    
			            mVelocityTracker = VelocityTracker.obtain();    
			            mVelocityTracker.addMovement(event); 
			    }        	 
	            if (!mScroller.isFinished()){    
	                mScroller.abortAnimation();    
	            }                
	            mLastMotionX = x;	           
	            mLastMotionY = y;	           
	            break;    
	                
	        case MotionEvent.ACTION_MOVE:  
	        	System.out.println("父类滑动onTouchEvent");
		           int deltaX = (int)(mLastMotionX - x);	           
	        	   if (IsCanMove(deltaX))
	        	   {
	        		 if (mVelocityTracker != null)
	  		         {
	  		            	mVelocityTracker.addMovement(event); 
	  		         }   
	  	            mLastMotionX = x;     
	  	            scrollBy(deltaX, 0);	
	        	   }
         
	           break;    	                
	        case MotionEvent.ACTION_UP:       
	        	System.out.println("父类放开onTouchEvent");
	        	int velocityX = 0;
	            if (mVelocityTracker != null)
	            {
	            	mVelocityTracker.addMovement(event); 
	            	mVelocityTracker.computeCurrentVelocity(1000);  
	            	velocityX = (int) mVelocityTracker.getXVelocity();
	            }	               	                
	            if (velocityX > SNAP_VELOCITY && mCurScreen > 0) {       
	                // Fling enough to move left       
	                Log.e(TAG, "snap left");    
	                snapToScreen(mCurScreen - 1);       
	            } else if (velocityX < -SNAP_VELOCITY       
	                    && mCurScreen < getChildCount() - 1) {       
	                // Fling enough to move right       
	                Log.e(TAG, "snap right");    
	                snapToScreen(mCurScreen + 1);       
	            } else {       
	                snapToDestination();       
	            }      
	            	            
	            if (mVelocityTracker != null) {       
	                mVelocityTracker.recycle();       
	                mVelocityTracker = null;       
	            }       
	      //      mTouchState = TOUCH_STATE_REST;
	            break;      
	        }    	            
	        return false;    
	}

三、数据传值问题

注意改变Adapter内的数据，如下：list_contents和toparr是改变后的数据

		mycqbaseAdapter.contents=list_contents;
		mycqtitleAdapter.toparr = toparr;
		mycqbaseAdapter.notifyDataSetChanged();
		mycqtitleAdapter.notifyDataSetChanged();

有一种错误的写法就是直接调用notifyData方法

		mycqbaseAdapter.notifyDataSetChanged();
		mycqtitleAdapter.notifyDataSetChanged();

四、ViewGroup中notifyDataSetChanged()无效

@Override   
protected void onLayout(boolean changed, int l, int t, int r, int b) {
// if (changed) {
menu_view = getChildAt(0);
content_view = getChildAt(1);


content_view.measure(0, 0);
content_view.layout(0, 0, getWidth(), getHeight());
// }
}

注释掉onLayout中的if(changed)即可。